PANASONIC-TX2SS-L2-9V-Z

Relay Technical Information  

Definition of Relay Terminology  

COIL

(also referred to as primary or input)  

• Nominal Coil Voltage

(Rated Coil  

Voltage)  

decreased, the value at or above which all  

contacts must revert to their unoperated  

position.  

• Maximum Continuous Voltage  

The maximum voltage that can be applied  

continuously to the coil without causing  

damage

.

S

hort duration spikes of a higher  

voltage may be tolerable, but this should  

not be assumed without first checking  

with the manufacturer.  

• Nominal Operating Power  

The value of power used by the coil at  

nominal voltage. For DC coils expressed  

in watts; AC expressed as volt amperes.  

Nominal Power (W or VA) = Nominal  

Voltage

×

Nominal Current.  

A single value (or narrow range) of source  

voltage intended by design to be applied  

to the coil or input.  

• Pick-U

p

V

oltage

(Pull-I

n

V

oltage or Must  

Operate Voltage)  

As the voltage on an unoperated relay is  

increased, the value at or below which all  

contacts must function (transfer).  

• Drop-Out Voltage

(Release or Must  

Release Voltage)  

• Coil Resistance  

This is the DC resistance of the coil in DC  

type relays for the temperature conditions  

listed in the catalog. (Note that for certain  

types of relays, the DC resistance may be  

for temperatures other than the standard  

20°C

68°

F

.)  

• Nominal Operating Current  

The value of current flow in the coil when  

nominal voltage is impressed on the coil  

As the voltage on an operated relay is  

• Coil Designation  

Single side stable type  

2 coil latching type  

1 coil latching type  

Non-polarized  

Polarized  

4-terminal  

3-terminal  

—

+

+

—

+

—

+

+

+

or  

or  

—

+

—

—

—

A black coil represents the energized  

state. For latching relays, schematic  

diagrams generally show the coil in its  

reset state. Therefore, the coil symbol is  

also shown for the reset coil in its reset  

state.  

CONTACTS

(secondary or output)  

• Contact Forms  

amperes (AC) which can safely be  

switched by the contacts

.

T

his value is the  

product of switching voltage x switching  

current, and will be lower than the  

maximum voltage and maximum current  

product.  

• Maximum Switching Voltage  

The maximum open circuit voltage which  

can safely be switched by the contacts.  

AC and DC voltage maximums will differ  

in most cases.  

• Minimum switching capability  

This value is a guideline as to the lowest  

possible level at which it will be possible  

for a low level load to allow switching

.

T

he  

level of reliability of this value depends on  

switching frequenc

y

,

a

mbient conditions,  

change in the desired contact resistance,  

and the absolute value. Please use a  

relay with AgPd contacts if your needs  

analog low level loads, control, or a  

contact resistance of 100 m

Ω

or less.  

We recommend that you verify with one of  

our sales offices regarding usage.  

• Maximum Switching Capacity  

Denotes the contact mechanism and  

number of contacts in the contact circuit.  

• Contact Symbols  

Form A contacts  

(normally open contacts)  

Form B contacts  

(normally closed contacts)  

• Maximum Switching Current  

The maximum current which can safely be  

switched by the contacts. AC and DC  

current maximums may differ.  

Form C contacts  

(changeover contacts)  

This is listed in the data column for each  

type of relay as the maximum value of the  

contact capacity and is an  

Form A contacts are also called N.O.  

contacts or make contacts.  

Form B contacts are also called N.C.  

contacts or break contacts.  

Form C contacts are also called  

changeover contacts or transfer contacts.  

• MBB Contacts  

Abbreviation for make-before-break  

contacts. Contact mechanism where  

Form A contacts (normally open contacts)  

close before Form B contacts open  

(normally closed contacts).  

• Maximum Switching Power  

The upper limit of power which can be  

switched by the contacts. Care should be  

taken not to exceed this value.  

interrelationship of the maximum  

switching power, maximum switching  

voltage, and maximum switching current.  

The switching current and switching  

voltage can be obtained from this graph.  

For example, if the switching voltage is  

fixed in a certain application, the  

maximum switching current can be  

obtained from the intersection between  

the voltage on the axis and the maximum  

switching power.  

• Maximum Carrying Current  

The maximum current which after closing  

or prior to opening, the contacts can  

safely pass without being subject to  

temperature rise in excess of their design  

limit, or the design limit of other  

temperature sensitive components in the  

relay (coil, springs, insulation, etc.). This  

value is usually in excess of the maximum  

switching current.  

• Rated Switching Power  

The design value in watts (DC) or volt  

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OPYRIGHT

Matsushita Electric Works, Ltd.  

Definition of Relay Terminology  

Maximum Switching Capacity  

(TX relay)  

Example: Using TX relay at a switching  

voltage of 60V DC, the maximum  

switching current is 1A.  

(Maximum switching capacity is given for  

a resistive load

.

B

e sure to carefully check  

the actual load before use.)  

• Contact Resistance  

Test Currents  

This value is the combined resistance of  

the resistance when the contacts are  

touching each other, the resistance of the  

terminals and contact spring

.

T

he contact  

resistance is measured using the voltage-  

drop method as shown below. The  

measuring currents are designated in  

Fig. 1.  

Rated Contact Current or  

Switching Current (A)  

T

e

st Current  

(mA)  

Less than 0.01  

1

10  

0.01 or more and less than 0.1  

0.1 or more and less than 1  

1 or more  

100  

1,000  

The resistance can be measured with  

reasonable accuracy on a YHP 4328A  

milliohmmeter.  

3.0  

2.0  

In general, for relays with a contact rating  

of 1A or more, measure using the voltage-  

drop method at 1A 6V DC.  

V

DC resistive load  

1.0  

• Capacitance  

This value is measured between the  

terminals at 1kHz and 20°C

68°

F

.  

Measured contact  

R

0.5  

0.4  

Power  

source  

0.3  

A

0.2  

(AC or DC)  

A :  

Ammeter

V :

 

Voltmeter

R :

Variable resister  

0

20 30

 

50  

100  

200 300  

Contact voltage, V  

Fig. 1  

PERFORMANCE  

• Insulation Resistance  

closure of the normally open contacts.  

(With multiple pole devices the time until  

the last contact closes.) This time does  

not include any bounce time.  

• Release Time

(Drop-Out Time)  

The elapsed time from the initial removal  

of coil power until the reclosure of the  

normally closed contacts (last contact  

with multi-pole) this time does not include  

bounce.  

• Set Time  

T

e

rm used to describe operate time of a  

latching rela

y

.  

• Reset Time  

T

e

rm used to describe release time of a  

latching rela

y

.

W

ith a 2-coil magnetic  

latching relay the time is from the first  

application of power to the reset coil until  

the reclosure of the reset contacts

.

W

ith a  

single coil latching rela

y

,

t

he time is  

measured from the first application of  

reverse coil voltage until the reclosure of  

the reset contact.  

• Shock Resistance, Destructive  

The acceleration which can be withstood  

by the relay during shipping or installation  

without it suffering damage, and without  

causing a change in its operating charac-  

teristics. Usually expressed in “G”s.  

• Shock Resistance, Functional  

The acceleration which can be tolerated  

by the relay during service without  

causing the closed contacts to open for  

more than the specified time. (usually  

10

µ

s)  

• Vibration Resistance, Destructive  

The vibration which can be withstood by  

the relay during shipping, installation or  

use without it suffering damage, and  

without causing a change in its operating  

characteristics. Expressed as an  

acceleration in G’s or displacement, and  

frequency range.  

The resistance value between all mutually  

isolated conducting sections of the rela

y

,  

i.e. between coil and contacts, across  

open contacts and between coil or  

contacts to any core or frame at ground  

potential. This value is usually expressed  

as “initial insulation resistance” and may  

decrease with time, due to material  

degradation and the accumulation of  

contaminants.  

• Breakdow

n

V

oltage

(Hi-Pot or Dielectric  

Strength)  

The maximum voltage which can be  

tolerated by the relay without damage for  

a specified period of time, usually  

measured at the same points as  

insulation resistance. Usually the stated  

value is in VAC (RMS) for one minute  

duration.  

• Surge Withstand Voltage  

• Vibration Resistance, Functional  

The vibration which can be tolerated by  

the relay during service, without causing  

the closed contacts to open for more than  

the specified time.  

The ability of the device to withstand an  

abnormal externally produced power  

surge, as in a lightning strike, or other  

phenomenon. An impulse test waveform  

is usually specified, indicating rise time,  

peak value and fall time. (Fig. 2)  

• Contact Bounce

(Time)  

Generally expressed in time (ms), this  

refers to the intermittent switching  

phenomenon of the contacts which  

occurs due to the collision between the  

movable metal parts or contacts, when  

the relay is operated or released.  

• Operate Bounce Time  

The time period immediately following  

operate time during which the contacts  

are still dynamic, and ending once all  

bounce has ceased.  

• Mechanical Life  

The minimum number of times the relay  

can be operated under nominal conditions  

(coil voltage, temperature, humidit

y

,

e

tc.)  

with no load on the contacts.  

1,500 V  

750 V  

• Electrical Life  

The minimum number of times the relay  

can be operated under nominal conditions  

with a specific load being switched by the  

contacts.  

• Release Bounce Time  

• Maximum Switching Frequency  

This refers to the maximum switching  

frequency which satisfies the mechanical  

life or electrical life under repeated  

operations by applying a pulse train at the  

rated voltage to the operating coil.  

10

µ

s  

160

µ

s  

The time period immediately following  

release time during which the contacts  

are still dynamic, ending when all bounce  

has ceased.  

Fig. 2  

• Operat

e

T

ime (Pull-In or Pick-U

p

T

ime)  

The elapsed time from the initial  

application of power to the coil, until the  

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Matsushita Electric Works, Ltd.  

Definition of Relay Terminology  

• Life Curve  

HIGH FREQUENCY CHARACTERISTICS  

This is listed in the data column for each  

type of rela

y

.

T

he life (number of  

operations) can be estimated from the  

switching voltage and switching current.  

For example, for a DS relay operating at:  

Switching voltage = 125V AC  

• Isolation  

•

V

.

S.W.R.

(Voltage Standing Wave Ratio)  

High frequency resonance is generated  

from the interference between the input  

signal and reflected (wave) signal.  

V

.

S.W.R. refers to the ratio of the  

maximum value to minimum value of the  

waveform

.

T

h

e

V

.

S.W.R

.

i

s 1 when there is  

no reflected wave. It usually becomes  

greater than 1.  

High frequency signals leak through the  

stray capacitance across contacts even if  

the contacts are separated. This leak is  

called isolation. The symbol dB (decibel)  

is used to express the magnitude of the  

leak signal. This is expressed as the  

logarithm of the magnitude ratio of the  

signal generated by the leak with respect  

to the input signal. The larger the  

magnitude, the better the isolation.  

• Insertion Loss  

At the high frequency region, signal  

disturbance occurs from self-induction,  

resistance, and dielectric loss as well as  

from reflection due to impedance  

mismatching in circuits

.

L

oss due to any of  

these types of disturbances is called  

insertion loss

.

T

herefore, this refers to the  

magnitude of loss of the input signal

.

T

he  

smaller the magnitude, the better the  

rela

y

.  

Switching current = 0.6A  

The life expectancy is 300,000  

operations. However, this value is for a  

resistive load. Be sure to carefully check  

the actual load before use.  

Notes:  

1. Except where otherwise specified, the  

tests above are conducted under  

standard temperature and humidity (15°C  

to 35°C

59°F to 95°

F

, 25 to 75%).  

2. The coil impressed voltage in the  

switching tests is a rectangular wave at  

the rated voltage.  

Life Curve  

1,000  

30V DC resistance load  

100  

3. The phase of the AC load operation is  

random.  

125V AC resistance load  

10  

1

2

Current (A)  

PROTECTIVE CONSTRUCTION  

Several different degrees of protection are  

provided for different relay types, for  

resistance to dust, flux, contaminating  

environments, automatic cleaning, etc.  

• Open Type  

For reasons of cost, some devices are not  

provided with any enclosure. It is usually  

assumed that the end application will be  

in an overall enclosure or protective  

environment.  

contamination, and also may protect user  

and chemical stabilit

y

.

T

his annealing  

process drives off residual volatiles in the  

plastics, insuring a contaminant free  

environment inside the sealed rela

y

,  

resulting in more stable contact  

personnel from a shock hazard.  

• Flux-Resistant Type  

In this type of construction, solder flux  

penetration is curtailed by either insert  

molding the terminals with the header, or  

by a simple sealing operation during  

manufacturing.  

resistance over life.  

• Hermetic Seal  

The plastic sealed type is not a true  

hermetic seal, there is an exchange of  

gas molecules through the plastic cover  

over time. The only true hermetic seals  

are metal to metal and glass to metal

.

T

he  

entire device is purged with dry nitrogen  

gas prior to sealing, improving reliabilit

y

.  

• Sealed Type  

This type of sealed relay totally excludes  

the ingress of contaminants by way of a  

sealing compound being applied to the  

header/cover interface. The constituent  

components are annealed for physical  

• Dust Cover Type  

Most standard relays are provided with a  

dust cover of some type

.

T

his protects the  

relay from large particulate  

CONSTRUCTION AND CHARACTERISTIC  

(

ꢀ

:

Y

e

s,

ꢁ

: No)  

Automatic  

Soldering  

Automatic  

Cleaning  

Harmful Gas  

Resistance  

T

y

pe  

Construction  

Characteristics  

Most basic construction where the case and base  

(or body) are fitted together.  

Dust Cover

T

y

pe  

ꢁ

ꢀ

ꢀ

ꢁ

ꢁ

ꢀ

ꢁ

ꢁ

ꢀ

Base  

T

e

rminals are sealed or molded simultaneousl

y

.  

The joint between the case and base is higher  

than the surface of the PC board.  

Flux-Resistant

T

y

pe  

Sealed

T

y

pe  

Base  

T

e

rminals, case, and base are filled with sealing  

resin.  

Sealing resin  

Metal case  

Metallic Hermetic  

Seal

T

y

pe  

Hermetically sealed with metal case and metal  

base.

T

e

rminals are sealed with glass.  

ꢀ

ꢀ

ꢀ

Glass  

Metal base  

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OPYRIGHT

Matsushita Electric Works, Ltd.  

Definition of Relay Terminology  

OPERATIONAL FUNCTION  

• Single Side Stable Type  

Relay which turns on when the coil is  

energized and turns off when de-  

energized. (Fig. 3)  

• 2 Coil Latching Type  

Relay with a latching construction  

composed of 2 coils: set coil and reset  

coil

.

T

he relay is set or reset by alternately  

applying pulse signals of the same  

polarit

y

.

(

Fig. 5)  

• Operation Indication  

Indicates the set and reset states either  

electrically or mechanically for easy  

maintenance. An LED wired type (LED  

wired HC relay), lamp type (lamp wired  

HP relay) are available. (Fig. 6)  

1

3

4 5  

+

1

3

4

5

6

–

12  

10 9 8  

+

–

Direction indication*  

TX relay  

+

12  

–

7

10  

9

8

Fig. 3  

Direction indication*  

TX relay  

LED wired  

HC relay  

• 1 Coil Latching Type  

Fig. 5  

Relay with a latching construction that can  

maintain the on or off state with a pulse  

input. With one coil, the relay is set or  

reset by applying signals of opposite  

polarities. (Fig. 4)  

Fig. 6  

1

3

4 5  

–

+

12  

10 9 8  

Direction indication*  

TX relay  

Fig. 4  

TERMINAL CONFIGURATION  

PC board  

PC board  

surface-mount  

terminal  

PC board through hole  

terminal  

Quick connect  

T

y

pe  

self-clinching  

terminal  

Plug-in terminal  

Screw terminal  

terminal  

T

y

pical relay  

type  

T

e

rminal  

configuration  

GQ, GN, TQ, TN, TK, TX,  

TX-D rela

y

,

D

S rela

y

,  

T

y

pical relay

 

DS-BT rela

y

,

R

P rela

y

,  

GQ-SMD,  

GN-SMD,  

TX-SMD,  

TQ-SMD  

HJ rela

y

,

H

C relay  

HE relay  

EP relay  

EJ relay  

TQ, TN, TK, TX,  

TX-D relay  

HP rela

y

,

H

E relay

 

JC relay  

HL rela

y

,

H

K relay

 

JR relay  

HN relay  

type  

JS rela

y

,

J

W rela

y

,  

SEB rela

y

,

J

Q rela

y

,  

PQ relay  

MOUNTING METHOD  

T

e

rminal socket  

T

y

pe  

Insertion mount  

Surface mount  

Socket mount  

TM relay  

TMP type  

mount  

Mounting  

configuration  

Terminal  

Socket  

GQ, GN, TQ, TN, TK, TX,  

T

y

pical relay

 

TX-D rela

y

,

D

S rela

y

,  

GQ-SMD,  

GN-SMD,  

TX-SMD,  

TQ-SMD  

HJ rela

y

,

H

C relay  

HP rela

y

,

H

G relay  

HL rela

y

,

H

K relay  

HN relay  

NC relay  

HC relay  

HL relay  

HC relay  

JR relay  

JC relay  

JR relay  

LF relay  

J

T

–

N relay  

type  

DS-BT rela

y

,

R

P rela

y

,  

SEB relay  

Notes: 1. Sockets are available for certain PC board relays. (SEB rela

y

,

S

T rela

y

,

e

tc.)  

2. M type (solder type) for direct screw mounting of case is also available. (HG relay)  

All Rights Reserved © C

OPYRIGHT

Matsushita Electric Works, Ltd.  

General Application Guidelines  

A relay may encounter a variety of  

ambient conditions during actual use  

resulting in unexpected failure

.

T

herefore,  

testing over a practical range under actual  

operating conditions is necessar

y

.  

Application considerations should be  

reviewed and determined for proper use  

of the rela

y

.  

CAUTIONS REGARDING SAFETY  

• Be absolutely sure not to exceed the  

specification ranges, such as coil rating,  

contact rating and switching life. Doing so  

may lead to abnormal heating, smoke,  

and fire.  

turn off the power when installing,  

heating, and fire, etc.  

maintaining and troubleshooting the relay  

(including connecting parts such as the  

terminal block and socket).  

• Perform terminal connections correctly  

after verifying the internal wiring diagrams  

in the catalog

.

C

onnecting incorrectly may  

cause unexpected malfunction, abnormal  

• Prepare with a redundant safety device  

construction if there is a possibility that  

such things as adhesion, contact failure or  

disconnection could cause bodily harm or  

property damage.  

• Be absolutely sure not to touch the  

charging part when the relay is on. Doing  

so may cause electrical shock. Be sure to  

METHOD OF DETERMINING SPECIFICATIONS  

Failsafe  

Specification item  

Consideration points regarding selection  

a) Rating  

b) Pick-up voltage (current)  

c) Drop-out voltage (current)  

d) Maximum continuous  

impressed voltage (current)  

e) Coil resistance  

1) Select relay with consideration for power source ripple.  

2) Give sufficient consideration to ambient temperature, for the coil temperature rise and hot  

start.  

3) When used in conjunction with semiconductors, additional attention to the application  

should be taken.  

Coil  

f) Impedance  

g)

T

e

mperature rise  

h) Input frequency for AC type  

1) It is desirable to use a standard product with more than the required number of contacts.  

2) It is beneficial to have the relay life balanced with the life of the device it is used in.  

3) Is the contact material matched to the type of load?  

It is necessary to take care particularly with low level usage.  

4) The rated life may become reduced when used at high temperatures.  

Life should be verified in the actual atmosphere used.  

a) Contact arrangement  

b) Contact rating  

c) Contact material  

d) Life  

e) Contact pressure  

f) Contact

 

resistance  

Contacts  

5) Depending on the circuit, the relay drive may synchronize with the AC load. As this will  

cause a drastic shortening of life should be verified with the actual machine.  

a) Operate time  

b) Release time  

c) Bounce time  

Operate time  

1) It is beneficial to make the bounce time short for sound circuits and similar applications.  

d) Switching frequency  

a) Vibration resistance  

b) Shock resistance  

c) Ambient temperature  

d) Life  

1) Give consideration to performance under vibration and shock in the use location.  

2) In particular, when used in high temperature applications, relay with class B or class F  

coil insulation may be required.  

Mechanical  

characteristics  

1) Selection can be made for connection method with plug-in type, printed circuit board  

type, soldering, tab terminals, and screw fastening type.  

2) For use in an adverse atmosphere, sealed construction type should be selected.  

3) Are there any special conditions?  

a) Mounting method  

b) Cover  

c) Size  

Other items  

BASICS ON REL

A

Y

H

ANDLING  

•

T

o

m

aintain initial performance, care  

should be taken to avoid dropping or  

hitting the rela

y

.  

coil polarity (+, –) for polarized relays.  

before use.  

• Proper usage requires that the rated  

voltage be impressed on the coil. Use  

rectangular waves for DC coils and sine  

waves for AC coils.  

• Be sure the coil impressed voltage does  

not continuously exceed the maximum  

allowable voltage.  

• Absolutely avoid using switching  

voltages and currents that exceed the  

designated values.  

• Do not exceed the usable ambient  

temperature values listed in the catalog.  

• Use the flux-resistant type or sealed type  

if automatic soldering is to be used.  

• Use alcohol based cleaning solvents  

when cleaning is to be performed using a  

sealed type rela

y

.  

• Avoid ultrasonic cleaning of all types of  

relays.  

• Avoid bending terminals, because it may  

cause malfunction.  

• As a guide, use a Faston mounting  

pressure of 40 to 70N {4 to 7kgf}for relays  

with tab terminals.  

• For proper use, read the main text for  

details.  

• Under normal use, the relay is designed  

so that the case will not detach.

T

o  

maintain initial performance, the case  

should not be removed. Relay  

characteristics cannot be guaranteed if  

the case is removed.  

• Use of the relay in an atmosphere at  

standard temperature and humidity with  

minimal amounts of dust, SO

2

, H

2

S, or  

organic gases is recommended.  

• Please avoid the use of silicon-based  

resins near the rela

y

,

b

ecause doing so  

may result in contact failure. (This applies  

to plastic

 

sealed type relays, too.)  

• Care should be taken to observe correct  

• The rated switching power and life are  

given only as guides. The physical  

phenomena at the contacts and contact  

life greatly vary depending on the type of  

load and the operating conditions.  

Therefore, be sure to carefully check the  

type of load and operating conditions  

All Rights Reserved © C

OPYRIGHT

Matsushita Electric Works, Ltd.  

General Application Guidelines  

PROBLEM POINTS WITH REGARD TO USE  

In the actual use of relays, various  

tests are necessary under the possible  

relay is a mass production item, and as a  

matter of principle, it must be recognized  

that the relay is to be used to the extent of  

such variations without the need for  

adjustment.  

ambient conditions are encountered, and  

because unforeseen events occur which  

can not be thought of on the drawing  

board, with regard to such conditions,  

range of operation. For example,  

consideration must always be given to  

variation of performance when relay  

characteristics are being reviewed. The  

REL

A

Y

C

OIL  

• AC operation type  

resistance due to temperature rise, must  

be given consideration for the worst  

possible condition of relay operation,  

making it necessary to consider the  

current value as 1.5 to 2 times the pick-up  

current. Also, because of the extensive  

use of relays as limit devices in place of  

meters for both voltage and current, and  

because of the gradual increase or  

decrease of current impressed on the coil  

causing possible delay in movement of  

the contacts, there is the possibility that  

the designated control capacity may not  

be satisfied. Thus it is necessary to  

exercise care. The DC type relay coil  

resistance varies due to ambient  

humming is stopped, but with a distorted  

waveform, that function is not displayed.  

Fig. 1 below shows an example of  

For the operation of AC relays, the power  

source is almost always a commercial  

frequency (50 or 60Hz) with standard  

voltages of 6, 12, 24, 48, 115, and 240V  

AC. Because of this, when the voltage is  

other than the standard voltage, the  

product is a special order item, and the  

factors of price, deliver

y

,

a

nd stability of  

characteristics may create  

waveform distortion.  

If the power source for the relay operating  

circuit is connected to the same line as  

motors, solenoids, transformers, and  

other loads, when these loads operate,  

the line voltage drops, and because of this  

the relay contacts suffer the effect of  

vibration and subsequent burn damage.  

In particular, if a small type transformer is  

used and its capacity has no margin of  

safet

y

,

w

hen there is long wiring, or in the  

case of household used or small sales  

shop use where the wiring is slender, it is  

necessary to take precautions because of  

the normal voltage fluctuations combined  

with these other factors. When trouble  

develops, a survey of the voltage situation  

should be made using a synchroscope or  

similar means, and the necessary  

counter-measures should be taken, and  

together with this determine whether a  

special relay with suitable excitation  

characteristics should be used, or make a  

change in the DC circuit as shown in Fig.  

2 in which a capacitor is inserted to  

absorb the voltage fluctuations.  

In particular, when a magnetic switch is  

being used, because the load becomes  

like that of a motor, depending upon the  

application, separation of the operating  

circuit and power circuit should be tried  

and investigated.  

inconveniences.

T

o

t

he extent that it is  

possible, the standard voltages should be  

selected.  

Also, in the AC type, shading coil  

resistance loss, magnetic circuit eddy  

current loss, and hysteresis loss exit, and  

because of lower coil efficienc

y

,

i

t is  

normal for the temperature rise to be  

greater than that for the DC type.  

Furthermore, because humming occurs  

when below the pick-up voltage and when  

above the rated voltage, care is required  

with regard to power source voltage  

fluctuations.  

For example, in the case of motor starting,  

if the power source voltage drops, and  

during the humming of the rela

y

,

i

f it  

reverts to the restored condition, the  

contacts suffer a burn damage and  

welding, with the occurrence of a false  

operation self-maintaining condition.  

For the AC type, there is an inrush current  

during the operation time (for the  

separated condition of the armature, the  

impedance is low and a current greater  

than rated current flows; for the adhered  

condition of the armature, the impedance  

is high and the rated value of current  

flows), and because of this, for the case of  

several relays being used in parallel  

connection, it is necessary to give  

consideration to power consumption.  

• DC operation type  

temperature as well as to its own heat  

generation to the extent of about 0.4%/

°

C,  

and accordingl

y

,

i

f the temperature  

increases, because of the increase in pic  

k-up and drop-out voltages, care is  

required.  

• Energizing voltage of AC coil  

In order to have stable operation of the  

rela

y

,

t

he energizing voltage should be  

basically within the range of +10%/-15%  

of the rated voltage. However, it is  

necessary that the waveform of the  

voltage impressed on the coil be a sine  

wave. There is no problem if the power  

source is commercially provided power,  

but when a stabilized AC power source is  

used, there is a waveform distortion due  

to that equipment, and there is the  

possibility of abnormal overheating. By  

means of a shading coil for the AC coil,  

Sine wave  

Approximate keystone wave  

Waveform with a  

this harmonic included  

For the operation of DC relays, standards  

exist for power source voltage and  

current, with DC voltage standards set at  

5, 6, 12, 24, 48, and 100

V

,

b

ut with regard  

to current, the values as expressed in  

catalogs in milliamperes of pick-up  

current.  

However, because this value of pick-up  

current is nothing more than a guarantee  

of just barely moving the armature, the  

variation in energizing voltage and  

resistance values, and the increase in coil  

Fig. 1 Distortion in an AC stabilized power source  

T

Switch  

C

100V AC  

24V DC  

R

Relay coil  

Fig. 2 Voltage fluctuation absorbing circuit using a condenser  

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Matsushita Electric Works, Ltd.  

General Application Guidelines  

• Power source for DC input  

As a power source for the DC type rela

y

, a  

battery or either a half wave or full wave  

rectifier circuit with a smoothing capacitor  

is used

.

T

he characteristics with regard to  

the excitation voltage of the relay will  

change depending upon the type of power  

source, and because of this, in order to  

display stable characteristics, the most  

desirable method is perfect DC.  

~

R

Relay  

Smoothing capacitor  

Ripple portion  

In the case of ripple included in the DC  

power source, particularly in the case of  

half wave rectifier circuit with a smoothing  

capacitor, if the capacity of the capacitor  

is too small, due to the influence of the  

DC portion  

Emean.  

Emax. Emin.  

Emax.

–

Emin  

Emax. = Maximum value of ripple portion  

Emin. = Minimum value of ripple portion  

Emean. = Average value of ripple portion  

Ripple percentage =  

×

100%  

Emean.  

Fig. 3  

ripple, humming develops and an  

unsatisfactory condition is produced

.

W

ith  

the actual circuit to be used, it is  

absolutely necessary to confirm the  

characteristics. (Fig. 3)  

[1] It is desirable to have less than a 5%  

ripple for the reed type rela

y

.  

[4] Coil applied voltage and the drop in  

voltage.  

Please verify that the actual voltage is  

applied to the coil at the actual load.  

Electrical life will be affected by the drop in  

voltage in the coil when load is turned on.  

[2] For the hinge type rela

y

, a

h

alf wave  

rectifier cannot be used, alone unless you  

use a smoothing capacitor

.

T

he ripple and  

the characteristics must be evaluated for  

proper usage.  

[3] For the hinge type rela

y

,

t

here are  

certain applications that may or maynot  

use the full wave rectifier on it’s own.  

Please check specifications with the  

original manufacture.  

With regard to our

T

–

Series (TQ, TN, TK,  

TX, TX-D, TQ-SMD) and SEB relays, it is  

necessary to give consideration to the use  

of a power source with less than a 5%  

ripple, but for the J series, NC relays,  

there is no hindrance to the operation.  

However, the pull-up force becomes  

somewhat weakened, and it is necessary  

to take care since the resistance to  

vibration and shock is reduced. Also  

ordinarily the following must be given  

thought.  

Shown on the right, is a circuit driven by  

the same power supply (batter

y

,

e

tc.) for  

both the coil and contact.  

• Coil temperature rise  

In addition to being a requirement for relay  

operation stabilit

y

,

t

he maximum  

continuous impressed coil voltage is an  

important constraint for the prevention of  

such problems as thermal deterioration or  

deformity of the insulation material, or the  

occurrence of fire hazards.  

In actual use with E-type insulation, when  

the ambient temperature is 40°C

104°

F

, a  

temperature rise limit of 80°C

176°F

is  

thought to be reasonable according to the  

resistance method. However, when  

complying with the Electrical Appliance  

and Material Safety Law, this becomes  

75°C

167°

F

.  

•

T

emperature rise due to pulse voltage  

When a pulse voltage with ON time of less  

than 2 minutes is used, the coil  

temperature rise bares no relationship to  

the ON time. This varies with the ratio of  

ON time to OFF time, and compared with  

continuous current passage, it is rather  

small. The various relays are essentially  

the same in this respect. (Fig. 4)  

• Pick-up voltage change due to coil  

temperature rise (hot start)  

range, but for miniature types it is for the  

most part 1/2 cycle (about 10ms).  

In DC relays, after continuous passage of  

current in the coil, if the current is turned  

OF

F

,

t

hen immediately turned ON again,  

due to the temperature rise in the coil, the  

pick-up voltage will become somewhat  

higher. Also, it will be the same as using it  

in a higher temperature atmosphere. The  

resistance/temperature relationship for  

copper wire is about 0.4% for 1

°

C, and  

with this ratio the coil resistance  

However, for the somewhat large type  

relay where bounce is large, the operate  

time is 7 to 16ms, with release time in the  

order of 9 to 18ms Also, in the case of DC  

operation, to the extent of large coil input,  

the operating time is rapid, but if it is too  

rapid, the “A” contact bounce time is  

extended.  

Current passage time  

%

• Stray circuits (bypass circuits)  

In the case of sequence circuit  

T

e

mperature rise  

value is 100%  

For continuous passage  

increases. That is, in order to operate of  

the rela

y

,

i

t is necessary that the voltage  

be higher than the pick-up voltage and the  

pick-up voltage rises in accordance with  

the increase in the resistance value.  

However, for some polarized relays, this  

rate of change is considerably smaller.  

• Operate time  

In the case of AC operation, there is  

extensive variation in operate time  

depending upon the point in the phase at  

which the switch is turned ON for coil  

excitation, and it is expressed as a certain  

construction, because of bypass flow or  

alternate routing, it is necessary to take  

care not to have erroneous operation or  

abnormal operation.

T

o

u

nderstand this  

condition while preparing sequence  

circuits, as shown in Fig. 5, with 2 lines  

written as the power source lines, the  

upper line is always

B

and the lower line  

v

(when the circuit is AC, the same  

thinking applies). Accordingly the

B

side  

is necessarily the side for making contact  

connections (contacts for relays, timers,  

limit switches, etc.), and the

v

side is the  

ON : OFF = 3 : 1  

ON : OFF = 1 : 1  

ON : OFF = 1 : 3  

About 80%  

About 50%  

About 35%  

1 : 1  

Time  

Fig. 4  

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Matsushita Electric Works, Ltd.  

General Application Guidelines  

load circuit side (relay coil, timer coil,  

magnet coil, solenoid coil, motor, lamp,  

etc.).  

a series circuit through A, R

1

, R

2

, and R

3

,  

correctly made. In addition, with regard to  

the DC circuit, because it is simple by  

means of a diode to prevent stray circuits,  

proper application should be made.  

and the relays will hum and sometimes  

not be restored to the drop out condition.  

The connections shown in Fig. 6 (b) are  

Upper side line  

Contact circuit  

Power source lines  

A

B

C

A

D

Load circuit  

R

Lower side line  

R

1  

R

2  

R

3  

B

Fig. 5 Example of a vertically written  

sequence circuit  

R

1  

R

2  

R

3  

C

Fig. 6 shows an example of stray circuits.  

In Fig. 6 (a), with contacts A, B, and C  

closed, after relays R

1

, R

2

, and R

3  

(a) Not a good example  

(b) Correct example  

Fig. 6 Stray circuits  

operate, if contacts B and C open, there is  

• Gradual increase of coil impressed  

voltage and suicide circuit  

When the voltage impressed on the coil is  

increased slowl

y

,

t

he relay transferring  

operation is unstable, the contact  

with mixture of gradual increase of  

impressed voltage for the coil and a  

sucide circuit. In the timing portion for  

relay R

1

, when the timing times out,  

chattering occurs causing trouble. In the  

initial test (trial production), it shows  

favorable operation, but as the number of  

operations increases, contact blackening  

(carbonization) plus the chattering of the  

relay creates instability in performance.  

pressure drops, contact bounce  

increases, and an unstable condition of  

contact occurs. This method of applying  

voltage to the coil should not be used, and  

consideration should be given to the  

method of impressing voltage on the coil  

(use of switching circuit). Also, in the case  

of latching relays, using self contacts “B

,

”  

the method of self coil circuit for complete  

interruption is used, but because of the  

possibility of trouble developing, care  

should be taken.  

Instability point  

R

1

a  

R

2

a  

Switch  

R

1

b  

X

R

2

b  

X

SW  

ON  

E

C

C

R

1  

R

2  

e

R

1

b  

R

1

a  

R

1

: Reed relay  

R

2

: Reed relay  

C: Capacitor  

X: Variable resistance  

(for time adjustment)  

R

1

a: Form A of relay R

1  

R

1

b: Form B of relay R

1  

The circuit shown in Fig

.

7

c

auses a timing  

and sequential operation using a reed  

type rela

y

, but this is not a good example  

Fig. 7 A timing and sequential operation using a reed type relay  

• Phase synchronization in AC load  

switching  

If switching of the relay contacts is  

synchronized with the phase of the AC  

power, reduced electrical life, welded  

contacts, or a locking phenomenon  

(incomplete release) due to contact  

material transfer may occur. Therefore,  

check the relay while it is operating in the  

actual system. When driving relays with  

timers, micro computers and thyristors,  

etc., there may be synchronization with  

the power supply phase. (Fig. 8)  

Load  

R

y  

Load  

voltage  

V

in.  

V

in.  

Fig. 8  

• Erroneous operation due to inductive  

interference  

caused by a problem with distribution  

capacity or the device might break down  

due to the influence of externally caused  

surges, such as that caused by lightning.  

• Long term current carrying  

operation.  

Continuous, long-term current to the coil  

will facilitate deterioration of coil insulation  

and characteristics due to heating of the  

coil itself.  

For circuits such as these, please use a  

magnetic-hold type latching rela

y

.

I

f you  

must use a single stable rela

y

,

u

se a  

sealed type relay that is not easily  

affected by ambient conditions and  

provide a failsafe circuit design that  

considers the possibility of contact failure  

or disconnection.  

For long wire runs, when the line for the  

control circuit and the line for power line  

use a single conduit, induction voltage,  

caused by induction from the power line,  

will be applied to the operation coil  

regardless of whether or not the control  

signal is off. In this case the relay and  

timer may not revert. Therefore, when  

wiring divs a long distance please  

remember that along with inductive  

interference, connection failure may be  

A circuit designed for non-excitation when  

left running is desirable for circuits  

(circuits for emergency lamps, alarm  

devices and error inspection that, for  

example, revert only during malfunction  

and output warnings with form B contacts)  

that will be carrying a current continuously  

for long periods without relay switching  

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Matsushita Electric Works, Ltd.  

General Application Guidelines  

• Usage with infrequent switching  

Please carry out periodic contact  

conductivity inspections when the  

frequency of switching is once or fewer  

times per month. When no switching of  

the contacts occurs for long periods,  

organic membrane may form on the  

contact surfaces and lead to contact  

instabilit

y

.  

• Regarding electrolytic corrosion of  

coils  

In the case of comparatively high voltage  

coil circuits (in particular above 48 V DC),  

when such relays are used in high  

temperature and high humidity  

(2) When a grounding is not required,  

important role as a method for preventing  

electrolytic corrosion.  

connect the ground terminal to the

B

side  

of the coil. (Refer to Fig. 11) (NF and NR  

with ground terminal)  

[3] When the

v

side of the power source  

is grounded, always avoid interting the  

contacts (and switches) in the

v

side.  

(Refer to Fig. 12) (Common to all relays)  

[4] In the case of relays provided with a  

ground terminal, when the ground  

Note: The designation on the drawing  

indicates the insertion of insulation  

between the iron core and the chassis. In  

relays where a ground terminal is  

provided, the iron core can be grounded  

directly to the chassis, but in  

consideration of electrolytic corrosion, it is  

more expedient not to make the  

connection.  

terminal is not considered effective, not  

making a connection to ground plays an  

Judgement: Good (Fig. 9)  

Judgement: Good (Fig. 10)  

Switch  

Bobbin  

Bobbin  

atmospheres or with continuous passage  

of current, the corrosion can be said to be  

the result of the occurrence of electrolytic  

corrosion. Because of the possibility of  

open circuits occurring, attention should  

be given to the following points.  

End of coil winding  

+

–

+

–

+

–

+

Iron core  

Relay coil  

Iron core  

Relay coil  

–

Start of coil winding  

R (Insulation  

resistance)  

R (Insulation  

resistance)  

Switch  

[1

]

T

he

B

side of the power source should  

be connected to the chassis

.

(

Refer to Fig.  

9) (Common to all relays)  

Judgement: Good (Fig. 11)  

Judgement: No good (Fig. 12)  

[2] In the case where unavoidably the

v  

side is grounded, or in the case where  

grounding is not possible.  

(1) Insert the contacts (or switch) in the

B  

side of the power source, and connect the  

start of the coil winding the

v

side

.

(

Refer  

to Fig. 10) (Common to all relays)  

Switch  

Bobbin  

+

+

+

–

+

+

Iron core  

Relay coil  

Iron core  

Relay coil  

–

–

Bobbin  

R (Insulation  

resistance)  

Switch  

CONTACT  

The contacts are the most important  

elements of relay construction. Contact  

performance conspicuously influenced by  

contact material, and voltage and current  

values applied to the contacts (in  

particular, the voltage and current  

waveforms at the time of application and  

release), the type of load, frequency of  

switching, ambient atmosphere, form of  

contact, contact switching speed, and of  

bounce.  

exercise care with regard to control  

capacit

y

.

I

n the case of DC, there is no  

zero current point such as there is with  

AC, and accordingl

y

,

o

nce a cathode arc  

has been generated, because it is difficult  

to quench that arc, the extended time of  

the arc is a major cause. In addition, due  

to the direction of the current being fixed,  

the phenomenon of contact shift, as noted  

separately below, occurs in relation to the  

contact wear. Ordinaril

y

,

t

he approximate  

control capacity is mentioned in catalogs  

or similar data sheets, but this alone is not  

sufficient

.

W

ith special contact circuits, for  

the individual case, the maker either  

estimates from the past experience or  

makes test

 

on each occasion. Also, in  

catalogs and similar data sheets, the  

control capacity that is mentioned is  

limited to resistive load, but there is a  

broad meaning indicated for that class of  

rela

y

,

a

nd ordinarily it is proper to think of  

current capacity as that for 125V AC  

circuits.  

ambient conditions, change in the desired  

contact resistance, and the absolute  

value. Please use relays with AgPd  

contacts when minute analog load control  

or contact resistance no higher than 100  

m

Ω

is desired (for measurement and  

wireless applications, etc.).  

[Current]  

The current at both the closing and  

opening time of the contact circuit exerts  

important influence. For example, when  

the load is either a motor or a lamp, to the  

extent of the inrush current at the time of  

closing the circuit, wear of the contacts,  

and the amount of contact transfer  

increase, and contact welding and contact  

transfer make contact separation  

impossible.  

Because of contact transfer, welding,  

abnormal wear, increase in contact  

resistance, and the various other  

damages which bring about unsuitable  

operation, the following items require full  

investigation.  

*We recommend that you verify with one  

of our sales offices.  

1. Contact circuit voltage, current, and  

load  

[Voltage, AC and DC]  

When there is inductance included in the  

circuit, a rather high counter emf is  

generated as a contact circuit voltage,  

and since, to the extent of the value of that  

voltage, the energy applied to the  

contacts causes damage with  

Minimum applicable loads are given in the  

catalog; however, these are only provided  

as a guide to the lower limit that the relay  

is able to switch and are not guaranteed  

values. The level of reliability of these  

values depends on switching frequenc

y

,  

consequent wear of the contacts, and  

transfer of the contacts, it is necessary to  

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Matsushita Electric Works, Ltd.  

General Application Guidelines  

2. Characteristics of Common Contact Materials  

Characteristics of contact materials are given below. Refer to them when selecting a rela

y

.  

Electrical conductivity and thermal conductivity are the highest of all metals. Exhibits low contact resistance, is  

inexpensive and widely used. A disadvantage is it easily develops a sulfide film in a sulfide atmosphere. Care is  

required at low voltage and low current levels.  

Ag  

(silver)  

AgCd  

(silver-cadmium)  

Exhibits the conductivity and low contact resistance of silver as well as excellent resistance to welding. Like silver,  

it easily develops a sulfide film in a sulfide atmosphere.  

Hardness and melting point are high, arc resistance is excellent, and it is highly resistant to material transfer.  

However, high contact pressure is required. Furthermore, contact resistance is relatively high and resistance to  

corrosion is poor. Also, there are constraints on processing and mounting to contact springs.  

Contact  

Material  

AgW  

(silver-tungsten)  

AgNi  

(silver-nickel)  

Equals the electrical conductivity of silver. Excellent arc resistance.  

AgPd  

(silver-palladium)  

At standard temperature, good corrosion resistance and good sulfidation resistance. However, in dry circuits,  

organic gases adhere and it easily develops a polymer. Gold clad is used to prevent polymer buildup. Expensive.  

Combines perfect corrosion resistance and hardness. As plated contacts, used for relatively light loads. In an  

organic gas atmosphere, care is required as polymers may develop. Therefore, it is used in hermetic seal relays  

(reed relays, etc.) . Expensive.  

Rh plating  

(rhodium)  

Au with its excellent corrosion resistance is pressure welded onto a base metal. Special characteristics are  

uniform thickness and the nonexistence of pinholes. Greatly effective especially for low level loads under relatively  

adverse atmospheres. Often difficult to implement clad contacts in existing relays due to design and installation.  

Au clad  

(gold clad)  

Surface  

Finish  

Au plating  

(gold plating)  

Similar effect to Au cladding. Depending on the plating process used, supervision is important as there is the  

possibility of pinholes and cracks. Relatively easy to implement gold plating in existing relays.  

Au flash plating  

Purpose is to protect the contact base metal during storage of the switch or device with built-in switch. However, a  

(gold thin-film plating)

 

certain degree of contact stability can be obtained even when switching loads.  

3. Contact Protection  

Generall

y

,

t

he critical dielectric  

• Counter EMF  

breakdown voltage at standard  

ON OFF  

E

0

When switching inductive loads with a DC  

relay such as relay sequence circuits, DC  

motors, DC clutches, and DC solenoids, it  

is always important to absorb surges (e.g.  

with a diode) to protect the contacts.  

When these inductive loads are switched  

off, a counter emf of several hundred to  

several thousand volts develops which  

can severely damage contacts and  

greatly shorten life. If the current in these  

loads is relatively small at around 1A or  

less, the counter emf will cause the  

ignition of a glow or arc discharge. The  

discharge decomposes organic matter  

contained in the air and causes black  

deposits (oxides, carbides) to develop on  

the contacts. This may result in contact  

failure.  

temperature and pressure in air is about  

200 to 300 volts. Therefore, if the counter  

emf exceeds this, discharge occurs at the  

contacts to dissipate the energy (

1

/

2

Li

2

)  

stored in the coil. For this reason, it is  

desirable to absorb the counter emf so  

that it is 200V or less.  

Peak voltage  

+

–

meter  

–

Several hundred  

to several  

thousand volts  

+

e

+

R

E

–

di  

dt  

e =

–

L  

(a)  

(b)  

Fig. 13  

In Fig. 13 (a), an emf (e = –L di/dt) with a  

steep waveform is generated across the  

coil with the polarity shown in Fig. 13 (b)  

at the instant the inductive load is  

switched off. The counter emf passes  

through the power supply line and  

reaches both contacts.  

• Material Transfer Phenomenon  

Material transfer of contacts occurs when  

one contact melts or boils and the contact  

material transfers to the other contact. As  

the number of switching operations  

increases, uneven contact surfaces  

develop such as those shown in Fig. 14.  

After a while, the uneven contacts lock as  

if they were welded together. This often  

occurs in circuits where sparks are  

produced at the moment the contacts  

“make” such as when the DC current is  

large for DC inductive or capacitive loads  

or when the inrush current is large  

(several amperes or several tens of  

amperes).  

Contact protection circuits and contact  

materials resistant to material transfer  

such as AgSnO, AgW or AgCu are used  

as countermeasures. Generall

y

, a  

concave formation appears on the  

cathode and a convex formation appears  

on the anode. For DC capacitive loads  

(several amperes to several tens of  

amperes), it is always necessary to  

conduct actual confirmation tests.  

Meterial transfer of contacts  

Fig. 14  

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General Application Guidelines  

• Contact Protection Circuit  

Use of contact protective devices or  

protection circuits can suppress the  

counter emf to a low level. However, note  

that incorrect use will result in an adverse  

effect.

T

y

pical contact protection circuits  

are given in the table below.  

(G: Good

 

NG: No Good)  

Application  

AC DC  

Circuit  

Features/Others  

Devices Selection  

If the load is a timer, leakage current flows  

through the CR circuit causing faulty operation.  

* If used with AC voltage, be sure the  

impedance of the load is sufficiently smaller  

than that of the CR circuit  

Contact  

As a guide in selecting r and c,  

r: 0.5 to 1

Ω

per 1V contact voltage  

c: 0.5 to 1

µ

F per 1A contact current  

Values vary depending on the properties of the  

load and variations in relay characteristics.  

Capacitor c acts to suppress the discharge the  

moment the contacts open. Resistor r acts to  

limit the current when the power is turned on  

the next time.

T

e

st to confirm. Use a capacitor  

with a breakdown voltage of 200 to 300

V

.

U

se  

AC type capacitors (non-polarized) for AC  

circuits.  

*

G

G

r

c

CR  

circuit  

Contact  

If the load is a relay or solenoid, the release time  

lengthens. Effective when connected to both  

contacts if the power supply voltage is 24 or 48V  

and the voltage across the load is 100 to 200

V

.  

r

G

c

The diode connected in parallel causes the  

Use a diode with a reverse breakdown voltage  

Contact  

energy stored in the coil to flow to the coil in the

 

at least 10 times the circuit voltage and a  

form of current and dissipates it as joule heat at

 

forward current at least as large as the load  

the resistance component of the inductive load.

 

current. In electronic circuits where the circuit  

This circuit further delays the release time  

compared to the CR circuit. (2 to 5 times the  

release time listed in the catalog)  

Diode  

circuit  

NG  

NG  

G

G

G

G

Diode  

voltages are not so high, a diode can be used  

with a reverse breakdown voltage of about 2 to  

3 times the power supply voltage.  

Contact  

Diode  

and  

zener  

diode  

circuit  

Effective when the release time in the diode  

circuit is too long.  

Use a zener diode with a zener voltage about  

the same as the power supply voltage.  

Using the stable voltage characteristics of the  

varistor, this circuit prevents excessively high  

voltages from being applied across the contacts.  

This circuit also slightly delays the release time.  

Effective when connected to both contacts if the  

power supply voltage is 24 or 48V and the  

voltage across the load is 100 to 200

V

.  

Contact  

Varistor  

Varistor  

circuit  

• Avoid using the protection circuits  

shown in the figures below.  

Fig. 15  

Contact  

Power  

Contact  

Although DC inductive loads are usually  

more difficult to switch than resistive  

loads, use of the proper protection circuit  

will raise the characteristics to that for  

resistive loads. (Fig. 15)  

Power  

C

C

No good  

No good  

supply  

supply  

Although extremely effective in arc suppression

 

Although extremely effective in arc suppression  

as the contacts open, the contacts are

 

as the contacts open, the contacts are  

susceptible to welding since energy is stored in

 

susceptible to welding since charging current  

C when the contacts open and discharge  

flows to C when the contacts close.  

current flows from C when the contacts close.  

• Mounting the Protective Device  

In the actual circuit, it is necessary to  

locate the protective device (diode,  

resistor, capacitor, varistor, etc.) in the  

immediate vicinity of the load or contact

.

I

f  

located too far awa

y

,

t

he effectiveness of  

the protective device may diminish. As a  

guide, the distance should be within  

50cm.  

• Abnormal Corrosion during High  

Frequency Switching of DC Loads  

(spark generation)  

If, for example, a DC valve or clutch is  

switched at a high frequenc

y

, blue-green  

rust may develop. This occurs from the  

reaction of nitrogen and oxygen in the air  

when sparks (arc discharge) are  

generated during switching.  

• Type of Load and Inrush Current  

The type of load and its inrush current  

characteristics, together with the  

T

y

pe of load  

Inrush current  

Resistive load  

Steady state current  

10 to 20 times the  

steady state current  

Solenoid load  

Motor load  

switching frequenc

y

,

a

re important factors  

which cause contact welding. Particularly  

for loads with inrush currents, measure  

the steady state and inrush current.  

Then select a relay which provides an  

ample margin of safet

y

.

T

he table on the  

right shows the relationship between  

typical loads and their inrush currents.  

Also, verify the actual polarity used since,  

depending on the rela

y

,

e

lectrical life is  

affected by the polarity of COM and NO.  

5 to 10 times the  

steady state current  

Incandescent lamp  

load  

10 to 15 times the  

steady state current  

Approx. 3 times the  

steady state current  

Mercury lamp load  

Sodium vapor lamp  

load  

1 to 3 times the  

steady state current  

20 to 40 times the  

steady state current  

Capacitive load  

T

r

ansformer load  

5 to 15 times the  

steady state current  

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General Application Guidelines  

Load Inrush Current Wave and Time  

(1) Incandescent Lamp Load  

(2) Mercury Lamp Load  

(3) Fluorescent Lamp Load  

i/i

o

]

3 times  

i/i

o

]

5 to 10 times  

L

Contacts  

i

i

i

o  

i

o  

C

i

i

o  

(for high power factor type)  

3 to  

5 minutes  

10 seconds  

or less  

Incandescent lamp  

The discharge tube, transformer, choke coil,  

capacitor, etc., are combined in common  

discharge lamp circuits. Note that the inrush  

current may be 20 to 40 times, especially if  

the power supply impedance is low in the  

high power factor type.  

Approx. 1/3 second  

Inrush current/rated current  

=i/i

o

= 10 to 15 times  

(4) Motor Load i/i

o

]

5 to 10 times  

(5) Solenoid Load  

(6) Electromagnetic Contact Load

 

(7) Capacitive Load  

i/i

o

]

10 to 20 times  

i/i

o

]

3 to 10 times  

i/i

o

]

20 to 40 times  

i

o  

i

i

i

o  

i

i

o  

i

o  

i

0.07  

to 0.1 second  

0.2 to 0.5 second  

•

Conditions become more harsh if plugging or inching  

is performed since state transitions are repeated.  

•

When using a relay to control a DC motor and brake,  

the on time surge current, normal current and off  

time brake current differ depending on whether the  

load to the motor is free or locked. In particular, with  

non-polarized relays, when using from b contact of  

from contact for the DC motor brake, mechanical life  

might be affected by the brake current. Therefore,  

please verify current at the actual load.  

1 to 2 cycles  

(1/60 to 1/30 seconds)  

Note that since inductance is great,  

the arc lasts longer when power is cut.  

The contact may become easily worn.  

1/2 to 2 cycles (1/120 to 1/30 seconds)  

• When Using Long Wires  

• Electrical life at high temperatures  

Verify at the actual use condition since  

electrical life may be affected by use at  

high temperatures.  

If long wires (100 to 300m) are to be used  

in a relay contact circuit, inrush current  

may become a problem due to the stray  

capacitance existing between wires. Add  

a resistor (approx. 10 to 50

Ω

) in series  

with the contacts. (Fig. 16)  

Equivalent circuit  

+

Contacts  

Stray capacitance  

Added resistor  

Wire  

(100 to 300m)  

of wire  

10 to 50

Ω  

Fig. 16  

• Phase Synchronization in Switching AC Loads  

If switching of the relay contacts is  

synchronized with the phase of the AC  

power, reduced electrical life, welded  

contacts, or a locking phenomenon  

R

y  

Load  

voltage  

Load  

voltage  

Load  

V

in  

(incomplete release) due to contact  

material transfer may occur. Therefore,  

check the relay while it is operating in the  

actual system. However, if problems  

V

in  

develop, control the relay using an  

appropriate phase. (Fig. 17)  

Fig. 17  

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Matsushita Electric Works, Ltd.  

General Application Guidelines  

4. Cautions on Use Related to Contacts  

• Connection of load and contacts  

Connect the load to one side of the power  

supply as shown in Fig. 18 (a). Connect  

the contacts to the other side. This  

prevents high voltages from developing  

between contacts. If contacts are  

connected to both side of the power  

supply as shown in Fig. 18 (b), there is a  

risk of shorting the power supply when  

relatively close contacts short.  

R

y  

E

E

(a)  

(b)  

R

y  

R

y  

R

y  

(a) Good example  

(b) Bad example  

Fig. 18  

• Dummy Resistor  

Since voltage levels at the contacts used  

in low current circuits (dry circuits) are  

low, poor conduction is often the result.  

One method to increase reliability is to  

add a dummy resistor in parallel with the  

load to intentionally raise the load current  

reaching the contacts.  

• Avoid Circuits Where Shorts Occur  

Between Form A and B Contacts  

(Fig. 19)  

R

1  

R

1  

R

2  

Push-botton  

switch  

N.C.  

N.O.  

COM  

M

R

Relay coil  

R

R

2  

3) R

1

, R

2

: Contacts for R  

1) R

1

, R

2

: Contacts for R  

: Double pole relay  

2)  

R

R

: Double pole relay  

1) The clearance between form A and B  

contacts in compact control components  

is small. The occurrence of shorts due to  

Fig. 19  

arcing must be assumed.  

• Shorts Between Different Electrodes  

Although there is a tendency to select  

miniature control components because of  

the trend toward miniaturizing electrical  

control units, care must be taken when  

selecting the type of relay in circuits where  

different voltages are applied between  

electrodes in a multi-pole rela

y

,

e

specially  

when switching two different power supply  

circuits. This is not a problem that can be  

determined from sequence circuit  

diagrams. The construction of the control  

component itself must be examined and  

sufficient margin of safety must be  

provided especially in creepage between  

electrodes, space distance, presence of  

barrier, etc.  

2) Even if the three N.C., and COM  

contacts are connected so that they short,  

a circuit must never be designed to allow  

the possibility of burning or generating an  

overcurrent.  

3) A forward and reverse motor rotation  

circuit using switching of form A and B  

contacts must never be designed.  

LATCHING REL

A

Y

S  

• Latching relays are shipped from the  

factory in the reset state. A shock to the  

relay during shipping or installation may  

cause it to change to the set state.  

Therefore, it is recommended that the  

relay be used in a circuit which initializes  

the relay to the required state (set or  

reset) whenever the power is turned on.  

• Avoid impressing voltages to the set coil  

and reset coil at the same time.  

(a) Parallel connection of set coils  

(+)  

(b) Parallel connection of set coils  

(+)  

S

1  

S

2  

S

3  

S

1  

S

2  

S

3  

Reset  

coil  

Reset  

coil  

Reset coil  

Reset coil  

Set coil  

Set coil  

Set coil  

Set coil  

(

–

)  

(

–

)  

• Connect a diode as shown since latching  

may be compromised when the relay is  

used in the following circuits.  

Diode connection  

Diode connection  

Diode connection  

Diode connection  

If set coils or reset coils are to be  

connected together in parallel, connect a  

diode in series to each coil. Fig. 20 (a),  

Fig. 20 (b) Also, if the set coil of a relay  

and the reset coil of another relay are  

connected in parallel, connect a diode to  

the coils in series. Fig. 20 (c)  

(c) Parallel connection of set coils and reset coils  

(d) Circuit with inductive load in parallel  

with the set coil or reset coil  

(+)  

(+)  

S

1  

S

2  

S

3  

S

Reset  

coil  

AC  

or DC  

Reset coil  

Motor  

Common relay  

coil  

M

Set coil  

If the set coil or reset coil is to be  

Set coil  

Set or  

reset coil  

connected in parallel with an inductive  

load (e.g. another electromagnetic relay  

coil, motor, transformer, etc.), connect a  

diode to the set coil or reset coil in series.  

Fig. 20 (d)  

(

–

)  

(

–

)  

Diode connection  

Diode connection

 

Diode connection  

Fig. 20  

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Matsushita Electric Works, Ltd.  

General Application Guidelines  

Use a diode having an ample margin of  

safety for repeated DC reverse voltage  

and peak reverse voltage applications  

and having an average rectified current  

greater than or equal to the coil current.  

• Avoid applications in which conditions  

include frequent surges to the power  

suppl

y

.  

• Four-

T

e

rminal Latching Relay  

In the 2 coil latching type circuit in Fig. 22,  

one terminal at one end of the set coil and  

one terminal at one end of the reset coil  

are connected in common and voltages of  

the same polarity are applied to the other  

side for the set and reset operations. In  

this type of circuit, short 2 terminals of the  

relay as noted in the next table

.

T

his helps  

to keep the insulation high between the  

two winding.  

Relay

T

y

pe  

1c  

T

e

rminal Nos.  

—

15 & 16  

*

DS  

2c  

4c  

Flat  

Slim  

5 & 6  

3 & 4  

*

NC  

ST  

SP  

DE  

JH  

• Avoid using the following circuit since  

self-excitation at the contacts will inhibit  

the normal keep state. (Fig. 21)  

2 & 4  

1 & 2  

6 & 8  

Notes:  

1. *DS4c and ST relays are constructed so that the set  

coil and reset coil are separated for high insulation  

resistance.  

2. DS

P

,

T

Q, TQ-SMD, TN, TX, and SEB relays are not  

applicable due to polarit

y

.  

R

Lb  

R

La  

Set switch  

Set coil  

Reset coil  

R

L  

Reset switch  

R

L

: Latching relay  

R

La

: Form A contacts of R

L  

R

Lb

: Form B contacts of R

L  

Bad example  

Fig. 21  

Fig. 22  

•

T

w

o Coil Latch Induction Voltage  

is generated on the reverse side coil when  

voltage is applied and shut off to each coil.  

Although the amount of induction voltage  

is about the same as the rated relay  

voltage, you must be careful of the  

reverse bias voltage when driving  

transistors.  

Each coil in a 2-coil latch relay is wound  

with a set coil and a reset coil on the same  

iron cores. Accordingl

y

,

i

nduction voltage  

HANDLING CAUTIONS FOR TUBE

P

ACKAGING  

Some types of relays are supplied in tube  

packaging. If you remove any relays from  

the tube packaging, be sure to slide the  

Slide in the plug.  

stop plug at one end to hold the remaining  

relays firmly together so they would not  

Stop plug  

move in the tube. Failing to do this may  

lead to the appearance and/or  

performance being damaged.  

AMBIENT ENVIRONMENT  

1. Ambient Temperature and  

3. NOx Generation  

on separate plates, using a rubber sheet  

to absorb the shock, and changing the  

direction of the shock to a perpendicular  

angle.  

5. Influence of External Magnetic  

Fields  

Permanent magnets are used in reed  

relays and polarized relays (including NR  

relays), and their movable parts are  

constructed of ferrous materials. For this  

reason, when a magnet or permanent  

magnet in any other large rela

y

,  

transformer, or speaker is located nearb

y

,  

the relay characteristics may change and  

faulty operations may result. The  

influence depends on the strength of the  

magnetic field and it should be checked at  

the installation.  

Atmosphere  

When a plastic sealed type relay is used  

in an atmosphere high in humidity to  

switch a load which easily produces an  

arc, the NO

x

created by the arc and the  

water absorbed from outside the relay  

combine to produce nitric acid. This  

corrodes the internal metal parts and  

adversely affects operation.  

Avoid use at an ambient humidity of  

85%RH or higher (at 20°C

68°F

). If use at  

high humidity is unavoidable, consult us.  

4. Vibration and Shock  

If a relay and magnetic switch are  

mounted next to each other on a single  

plate, the relay contacts may separate  

momentarily from the shock produced  

when the magnetic switch is operated and  

result in faulty operation.  

Be sure the ambient temperature at the  

installation does not exceed the value  

listed in the catalog. Furthermore,  

environmentally sealed types (plastic  

sealed type, metallic hermetic seal type)  

should be considered for applications in  

an atmosphere with dust, sulfur gases  

(SO

2

, H

2

S), or organic gases.  

2. Silicon Atmosphere  

Please use something other than silicon  

based materials (silicon rubber, silicon oil,  

silicon-based coatings, and silicon bulking  

agents, etc.) in the vicinity of the relay  

since their use will generate volatile gas.  

When contacts are switched in such an  

environment, silicon may adhere to the  

contacts and lead to contact failure (in  

plastic seal types, too).  

Countermeasures include mounting them  

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Matsushita Electric Works, Ltd.  

General Application Guidelines  

6. Usage, storage, and transport  

conditions  

• Pressure: 86 to 106 kPa  

functional disorder. Please verify the  

environment for storing and transporting.  

• Packaging should be designed to  

reduce, as much as possible, the  

influence of humidit

y

,

o

rganic gas and  

sulfide gas when packaging.  

• Since the SMD type is sensitive to  

humidity it is packaged with tightly sealed  

anti-humidity packaging. However, when  

storing, please be careful of the following.  

(1) Please use promptly once the anti-  

humidity pack is opened. (As a guide, use  

within one week.)  

(2) When storing for a long period after  

opening the anti-humidity pack, storage in  

a humidity-controlled desicator or in anti-  

humidity packaging with an anti-humidity  

bag to which silica gel has been added, is  

recommended. (As a guide, storage can  

be for three months.)  

The humidity range varies with the  

temperature. Use within the range  

indicated in the graph above.  

1) During usage, storage, or  

transportation, avoid locations subject to  

direct sunlight and maintain normal  

temperature, humidit

y

,

a

nd pressure  

conditions.  

2) Condensation  

Condensation forms when there is a  

sudden change in temperature under high  

temperature, high humidity conditions.  

Condensation will cause deterioration of  

the relay insulation.  

3) Freezing  

Condensation or other moisture may  

freeze on the relay when the  

temperatures is lower than 0°C

32°

F

.  

This causes problems such as sticking of  

movable parts or operational time lags.  

4) Low temperature, low humidity  

environments  

The plastic becomes brittle if the relay is  

exposed to a low temperature, low  

humidity environment for long periods of  

time.  

The allowable specifications for  

environments suitable for usage, storage,  

and transportation are given below.  

•

T

e

mperature

:

T

he allowable temperature  

range differs for each rela

y

,

s

o refer to the  

relay’s individual specifications.  

In addition, when transporting or storing  

relays while they are tube packaged,  

there are cases when the temperature  

may differ from the allowable range.  

In this situation, be sure to consult the  

individual specifications.  

• Humidity: 5 to 85 % R.H.  

7.Vibration

,

I

mpact and Pressure when  

Shipping  

TX(-SMD) / TX-D(-SMD) / TQ-SMD  

Humidity, %R.H.  

• Be aware that plastic may become brittle  

in low-temperature, low-humidity  

environments.  

When shipping, if strong vibration, impact  

or heavy weight is applied to a device in  

which a relay is installed, functional  

damage may occur. Therefore, please  

package in a wa

y

,

u

sing shock absorbing  

material, etc., so that the allowable range  

for vibration and impact is not exceeded.  

85  

When stored in high-temperature, high-  

humidity environments, and in  

environments with organic or sulfide  

gases for long periods of time (including  

during transport), sulfide or oxide  

membrane will form on the surfaces of the  

contacts, which may lead to contact  

instability or malfunction, as well as  

Tolerance range  

(Avoid freezing when  

used at temperatures  

lower than 0

°

C

32

°

F

)  

(Avoid  

condensation when  

used at temperatures  

higher than 0

°

C

32

°

F

)  

5

–

40  

0

+85  

–

40  

+32  

+185  

Temperature,

°

C

°

F  

ENVIRONMENTAL

L

Y

S

EALED TYPE REL

A

Y

S  

Sealed type relays are available

.

T

hey are  

effective when problems arise during PC  

board mounting (e.g. automatic soldering  

and cleaning). They also, of course,  

feature excellent corrosion resistance.  

Note the cautions below regarding the  

features and use of environmentally  

sealed type relays to avoid problems  

when using them in applications.  

avoid atmospheric pressures beyond  

96 10kPa.

 

Also avoid using them in an  

atmosphere containing flammable or  

explosive gases. Use the metallic  

1. Operating Environment  

Plastic sealed type relays are not suited  

for use in environments that especially  

require air tightness. Although there is no  

problem if they are used at sea level,  

hermetic seal types for these applications.  

PROCESSING CONSIDERATIONS  

1. Handling  

supplied in prime condition. Some key  

researched carefull

y

.

A

n unsealed relay is  

prone to internal flux contamination which  

can compromise contact performance,  

and ideally should be hand soldered.  

“Flux-resistant” relays are available which  

will prevent flux migration through the  

terminal-header interface. These and  

“sealed” relays are compatible with mist  

foam or spray fluxing operations, however  

“Flux-resistant” types are not totally  

sealed which precludes washing  

State of the art relays are precision  

mechanical devices and as such are  

sensitive to abusive handling practices.  

Every attempt is made during their  

manufacture to preclude any anomalies.  

Relays are packed in a variety of ways to  

best protect them during shipment and  

subsequent handling. These include the  

use of “Egg Crate” type inserts which  

support the relay and prevent damage to  

the terminals, foam trays which prevent  

shock damage, and tubes similar to those  

used by semiconductor manufacturers for  

machine dispensing and assembl

y

.  

During incoming inspection and  

areas of concern:  

(1)

T

e

rminals should not be handled in  

order to prevent contamination of the  

surface finish. This could lead to  

solderability problems.  

(2)

T

e

rminal layout and

P

.

C. board hole  

pattern should match. Any misalignment  

caused by mis-registered

P

.

C. board  

holes can lead to severe stress on the  

rela

y

,

c

ompromising performance and  

reliability (seal integrity).  

operations, and makes a non-active flux  

almost a necessit

y

.  

(3) The storage temperature specification  

should be observed.  

(4) Relays should be stored and handled  

in a suitably clean area.  

Pre-heating the board assembly prior to  

soldering “Flux-resistant” types will dry  

the flux and further help to prevent flux  

being driven into the relay during the  

soldering operation.  

subsequent customer handling  

2. Fluxing  

operations, care should be taken so as  

not to degrade the device which has been  

Depending upon the type of relay  

involved, fluxing procedures should be  

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Matsushita Electric Works, Ltd.  

General Application Guidelines  

3. Soldering  

should not be exceeded. The use of an  

relay should be avoided. Sealed devices  

can be immersion cleaned in a suitable  

solvent (see solvent compatibility chart).  

Cleaning in a ultrasonic bath should also  

be avoided. A harmonic of the bath  

frequency may be induced in the contacts  

causing friction welding and subsequent  

contact sticking. Relays with a removable  

“vent” tab should be vented after cooling  

to room temperature following cleaning  

and drying.  

As with fluxing, automated soldering  

processes can, unless controlled  

carefull

y

,

c

ompromise the performance of  

unsealed relays.  

Flux-resistant and sealed types are  

compatible with mist dip or wave soldering  

procedures. Some state-of-the-art relays  

are suitable for various reflow processes,  

such as I.R. or vapor phase maximum  

soldering temperatures and times will  

vary from relay type to relay type, and  

I.R. reflow process with a relay not  

specifically designed to withstand the  

process, will in all probability degrade the  

relay and cause performance problems

.

A  

safe practice would be to review the  

thermal profile of the process on a case  

by case basis with your local Matsushita  

office.  

4. Cleaning  

Any cleaning process which involves  

potential contamination of an unsealed  

MOUNTING CONSIDERATIONS  

•

Top View and Bottom View  

Relays used for PC boards, especially the  

flat type relays, have their top or bottom  

surface indicated in the terminal wiring  

diagrams.  

the vibration and shock resistance of  

buildup.  

Form B contacts while the coil is not  

excited is greatly affected by the mounting  

direction of the rela

y

.  

This also applies when a large number of  

boards mounted with relays are installed  

as in a card rack. Be sure the ambient  

temperature of the relay does not exceed  

the value listed in the catalog.  

•

In

fl

uence of Adjacent Mounting of  

Polarized Relays  

When polarized relays are mounted close  

together, their characteristics change.  

Since the affect of adjacent mounting  

differs according to the type of rela

y

,

r

efer  

to the data for the particular type.  

•

Panel Mounting  

-Do not remove the panel. It has a special  

function

.

(

It will not come off under normal  

handling.)  

-When installing please use washers to  

prevent damage and deformation. Please  

keep the tightening torque to within 0.49  

to 68.6 N (5 to 7 kgf). Also, please use a  

spring washer to prevent it from coming  

loose.  

•

Contact Reliability  

Relay with  

terminals viewed  

from the bottom  

(terminals cannot  

be seen from the  

Mounting the relay so the surfaces of its  

contacts (fixed contacts or movable  

contacts) are vertical prevents dirt and  

dust as well as scattered contact material  

(produced due to large loads from which  

arcs are generated) and powdered metal  

from adhering to them.  

top)  

Relay with  

terminals viewed  

from the top (all  

terminals can be  

seen from the top)  

Note during PC  

Furthermore, it is not desirable to switch  

both a large load and a low level load with  

a single rela

y

.

T

he scattered contact  

material produced when switching the  

large load adheres to the contacts when  

switching the low level load and may  

cause contact failure. Therefore, avoid  

mounting the relay with its low level load  

contacts located below the large load  

contacts.  

board pattern  

design (NL, NC)  

•

Mounting Direction  

Mounting direction is important for  

optimum relay characteristics.  

•

Adjacent Mounting  

•

Shock Resistance  

When many relays are mounted close  

together, abnormally high temperatures  

may result from the combined heat  

generated. Mount relays with sufficient  

spacing between them to prevent heat  

•

Tab Terminals  

It is ideal to mount the relay so that the  

movement of the contacts and movable  

parts is perpendicular to the direction of  

vibration or shock. Especially note that  

As a guide, use a quick connect mounting  

pressure of 40 to 70N {4 to 7 kgf} for  

relays with tab terminals.  

METHOD OF MOUNTING  

• The direction of mounting is not  

specifically designated, but to the extent  

possible, the direction of contact  

movement should be such that vibration  

and shock will not be applied.  

When a terminal socket is used  

• After drilling the mounting holes, the  

terminal socket should be mounted  

making certain the mounting screws are  

not loose. DIN standard sockets are  

available for one-touch mounting on DIN  

rail of 35mm

1.378 inch

width.  

When reversible terminal sockets are  

used  

• The reversible terminal sockets (HC, HL  

socket) are for one-touch mounting. (A  

panel thickness of 1 to 2mm

.039 to .079  

inch

should be used.) (Fig. 23)  

Fig. 24  

• When all four of the projections are  

visible from the back side of the mounting  

panel, the mounting is completed and the  

socket is fastened.  

•

T

o

r

emove the socket, the projections on  

the side of the mounting bracket should  

be pushed inward and at the same time  

the body of the socket should be pushed  

lightly from the back side

.

T

he socket can  

then be removed from the panel.  

Fig. 23  

• The socket should be pushed through  

the opening in the mounting panel until  

the projections on the side of the  

mounting bracket extend out over the  

back surface. (Fig. 24)  

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General Application Guidelines  

REGARDING CONNECTION OF LEAD WIRES  

• When making the connections,  

• When the terminal board uses screw  

fastening connections, either pressure  

terminals or other means should be used  

to make secure fastening of the wire.  

To

p

revent damage and deformit

y

,

p

lease  

use a torque within the following range  

when tightening the push screw block of  

the terminal block.  

M4.5 screw:  

1.47 to 1.666 N·m (15 to 17 kgf·cm)  

M4 screw:  

1.176 to 1.37 N·m (12 to 14 kgf·cm)  

M3.5 screw:  

M3 screw:  

0.49 to 0.69 N·m (5 to 7 kgf·cm)  

depending upon the size of load, the wire  

cross-section should be at least as large  

as the values shown in the table below.  

Permissible current

 

Cross-section (mm

2

)  

2

3

0.2  

0.3  

0.5  

0.75  

1.25  

2

5

7.5  

12.5  

15  

20  

30  

2

3.5  

0.784 to 0.98 N·m (8 to 10 kgf·cm)  

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General Application Guidelines  

CAUTIONS FOR USE

–

Check List  

Check Item  

1. Is

 

the correct rated voltage applied?  

2. Is

 

the applied coil voltage within the allowable continuous voltage limit?  

3. Is

 

the ripple in the coil voltage within the allowable level?  

4. For

 

voltage applied to a polarized coil, is polarity observed?  

5. When

 

hot start is required, is the increase in coil resistance resulting from coil temperature rise taken into account  

in setting coil voltage?  

Coil Drive Input  

6. Is

 

the coil voltage free from momentary drop caused by load current?  

(Pay special attention for self-holding relays.)  

7. Is

 

supply voltage fluctuation taken into account when setting the rated coil voltage?  

8. The

 

relay status may become unstable if the coil voltage (current) is gradually increased or decreased.  

Was the relay tested in a real circuit or with a real load?  

9. When

 

driving with transistors, did you consider voltage drops?  

1. Is

 

the load rated within the contact ratings?  

2. Does

 

the load exceed the contacts’ minimum switching capacity?  

3. Special

 

attention is required for contact welding when the load is a lamp, motor, solenoid, or electromagnetic  

contractor.  

4. Was

 

the relay tested with a real load?  

A DC load may cause contact lock-up due to large contact transfer. Was the relay tested with a real load?  

5. For

 

an inductive load, is a surge absorber used across the contacts?  

6. When

 

an inductive load causes heavy arc discharge across the relay contacts, the contacts may be corroded by  

chemical reaction with nitrogen in the atmosphere. Was the relay tested with a real load?  

Load  

(Relay contacts)  

7. Platinum

 

contacts may generate brown powder due to a catalyzer effect or vibration energy.  

Was the relay tested with a real load?  

8. Is

 

the contact switching frequency below the specification?  

9. When

 

there are more than two sets of contacts (2T) in a rela

y

,

m

etallic powder shed from one set of contacts may  

cause a contact failure on the other set (particularly for light loads). Was the relay tested in a real circuit?  

10. A

 

delay capacitor used across relay contacts may cause contact welding. Was the relay tested with a real load?  

11. For

 

an AC rela

y

, a

l

arge contact bounce may cause contact welding. Was the relay tested in a real circuit or with a  

real load?  

12. A

 

high voltage may be induced at transformer load. Was the relay tested with a real load?  

1. Does

 

circuit design take into account electrolytic corrosion of the coil?  

2. Are

 

transistors and other circuit components protected rom counter electromotive force that develops across the  

relay coil?  

3. Is

 

the circuit designed so the relay coil is left deenergized while the relay is inactive for long period of time?  

4. Is

 

the relay operated within the ratings approved by the relevant international standard (if compliance is required)?  

5. Is

 

the circuit protected from malfunction when the relay’s activation and/or deactivation time varies considerably?  

6. Is

 

the circuit protected from malfunctions that might result from relay contact bounce?  

7. Is

 

the circuit protected from malfunction when a high-sensitivity self-holding rela

y

,

s

uch as NR type, is to be used?  

8. When

 

there are two or more sets of contacts (2T) in a rela

y

,

a

rc discharges from load switching may cause short  

circuits across the two or more sets of contacts. Is the circuit designed to suppress such arc discharges?  

Circuit Design  

9. Item

 

8 above also requires special attention when loads are supplied from separate power sources.  

10. Does

 

the post-installation insulation distance comply with the requirement of the relevant international standard or  

the Electrical Appliance and Material Control Law?  

11. Is

 

the circuit protected from malfunction when the relay is to be driven by transistors?  

12. When

 

the SCR is used for on/off control, the relay activation tends to synchronize with the line frequency, resulting  

in an extremely shortened life. Was the relay tested in a real circuit or with a real load?  

13. Does

 

the PC board design take into account use of on-board relay?  

14. RF

 

signals may leak across relay’s open contacts. Check for adequate contact isolation and use RF relays as  

needed.  

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General Application Guidelines  

Check Item  

1. Is

 

the ambient temperature in the allowable operating temperature range?  

2. Is

 

relative humidity below 85 percent?  

3. Is

 

the operating atmosphere free from organic and sulfide gases?  

4. Is

 

the operating atmosphere free from silicon gas? Depending on the load type, silicon gas may cause a black  

substance to from on the contacts, leading to contact failure.  

5. Is

 

the operating atmosphere free from excessive airborne dust?  

Operating  

Environment  

6. Is

 

the relay protected from oil and water splashes?  

7. Is

 

the relay protected from vibration and impact which may cause poor contact with the socket?  

8. Is

 

ambient vibration and impact below the level allowable for the relay?  

9. Is

 

the relay free from mechanical resonance after it is installed in position?  

10. Is

 

insulation coating applied to the relay along with the PC board? Depending on the load type, a black substance  

may form to cause contact failure.  

1. Is

 

the relay protected from solder chips and flux when it is manually soldered?  

2. Are

 

preparations for flux application and automatic soldering complete?  

3. Is

 

the PC board cleaning process designed to minimize adverse affects to the relays?  

4. Are

 

adequate separations provided between polarized or reed relays to prevent magnetic coupling?  

5. Are

 

the relay terminals free from stress in the socket?  

6. Polarized

 

relay’s characteristics may be affected by strong external magnetic field. Are the relays installed away  

from such fields?  

7. If

 

very long leads (100 to 300 meters) are used to connect the load, the stray capacity existing across the leads  

may cause a surge current. Was the relay tested with a real load?  

Installation and  

Connection  

8. Unless

 

otherwise specified, all relay terminals should be soldered at 250°C

482°F

within 5 sec. or at 350°C

662°F  

within 3 sec.  

9. A

 

badly warped PC board can cause stress to the relay terminals which may lead to degraded relay  

characteristics.  

10. Glass

 

shot should not be used to clean the PC board of solder flux

.

T

his may cause relay malfunction due to glass  

powder becoming lodged in the relay’s internal structure.  

11. Relays

 

should always be used with their plastic shields installed, or degraded relay performance may result.  

12. Do

 

not cut away any relay terminal as the stress may cause degraded relay performance.  

1. Is

 

the relay subject to freezing or condensation (especially when shipping)?  

2. Is

 

the temperature in the allowable temperature range?  

3. Is

 

the humidity in the allowable humidity range?  

4. Is

 

the storing atmosphere free from organic and sulfide gases?  

5. Is

 

the storing atmosphere free from excessive airborne dust?  

6. Is

 

the relay protected from oil and water splashes?  

Storage and  

T

r

ansport  

7. Is

 

the relay subject to the application of heavy weight?  

8. When

 

shipping does vibration and impact exceed the allowable range?  

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Reliability  

•

What is Reliability?  

1. Reliability in a Narrow Sense of the  

3. Intrinsic Reliability and Reliability of  

Use  

Reliability is “built” into products. This is  

referred to as intrinsic reliability which  

consists mainly of reliability in the narrow  

sense.  

Product reliability at the user’s site is  

called “reliability of use”, which consists  

mainly of reliability in the broad sense. In  

the relay industr

y

,

r

eliability of use has a  

significance in aspects of servicing.  

T

e

rm  

In the industrial world, reliability is an  

index of how long a particular product  

serves without failure.  

2. Reliability in a Board Sense of the

T

e

rm  

Every product has a finite service lifetime.  

This means that no product can continue  

normal service infinitel

y

.

W

hen a product  

has broken down, the user may throw it  

away or repair it. The reliability of  

repairable products is recognized as  

“reliability in a broad sense of the term”.  

For repairable products, their  

serviceability or maintainability is another  

problem. In addition, reliability of product  

design is becoming a serious concern for  

the manufacturing industr

y

.

I

n short,  

reliability has three senses: i.e. reliability  

of the product itself, serviceability of the  

product, and reliability of product design.  

1. Reliability (narrow sense), durability  

Long life time: MTTF, B

10

, R(T),  

Low failure rate: Lamda (

λ

), MTBF  

2. Maintainability  

MTTR  

Reliability  

(broad sense)  

Availability  

Preventive maintenance, predicted  

maintenance  

3. Design reliability  

Human factor, redundancy,  

fool-proof, fail-safe  

•

Reliability Measures  

The following list contains some of the  

1. Degree of Reliability  

4. Failure Rate  

most popular reliability measures:  

Degree of reliability represents  

percentage ratio of reliabilit

y

. For  

example, if none of 10 light bulbs has  

failed for 100 hours, the degree of  

reliability defined in, 100 hours of time is  

10/10 = 100%. If only three bulbs  

remained alive, the degree of reliability is  

3/10 = 30%.  

The JIS Z8115 standard defines the  

degree of reliability as follows:  

The probability at which a system,  

equipment, or part provides the specified  

functions over the intended duration  

under the specified conditions.  

2. MTBF  

MTBF is an acronym of mean time  

between failures. It indicates the mean  

time period in which a system, equipment,  

or part operates normally between two  

incidences of repair

.

M

TBF only applies to  

repairable products.  

MTBF tells how long a product can be  

used without the need for repair.  

Sometimes MTBF is used to represent  

the service lifetime before failure.  

3. MTTF  

Failure rate includes mean failure rate and  

momentary failure rate.  

Mean failure rate is defined as follows:  

Sample  

Reliability measure  

representation  

Degree of reliability R(T)  

MTBF  

99.9%  

100 hours  

100 hours  

20 fit, 1%/hour  

50 hours  

Mean failure rate

=

T

o

tal failure count/total  

operating hours  

MTTF  

Failure rate

λ  

Safe life B

10  

In general, failure rate refers to  

momentary failure rate. This represents  

the probability at which a system,  

equipment, or part, which has continued  

normal operation to a certain point of  

time, becomes faulty in the subsequent  

specified time period.  

Failure rate is often represented in the unit  

of percent/hours

.

F

or parts with low failure  

rates, “failure unit (Fit) = 10

9

/hour” is often  

used instead of failure rate. Percent/count  

is normally used for relays.  

f(t)  

T

Time  

(a) R(T)  

5. Safe Life  

MTTF  

Safe life is an inverse of degree of  

reliabilit

y

.

I

t is given as value B which  

makes the following equation true:  

1 – R(B) =

t

%  

MTTF is an acronym of mean time to  

failure. It indicates the mean time period  

until a product becomes faulty MTTF  

normally applies to unrepairable products  

such as parts and materials.  

In general, “B[1 – R(B)] = 10%” is more  

often used. In some cases this represents  

a more practical value of reliability than  

MTT

F

.  

(b) MTTF  

The relay is one of such objective of  

MTT

F

.  

10%  

B

10  

(c) Safe life  

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Matsushita Electric Works, Ltd.  

Reliability  

•

Failure  

[1] What is Failure?  

(III) Wear-out failure period  

Weibull distribution can be adopted to the  

actual failure rate distribution if the three  

variables above are estimated.  

Failure is defined as a state of system,  

equipment, or component in which part of  

all of its functions are impaired or lost.  

[2] Bathtub Curve  

In the final stage of the product’s service  

lifetime comes the wear-out failure period,  

in which the life of the product expires due  

to wear of fatigue. Preventive  

Product’s failure rate throughout its  

lifetime is depicted as a bathtub curve, as  

shown below. Failure rate is high at the  

beginning and end of its service lifetime.  

(I) Initial failure period  

The high failure rate in the initial failure  

period is derived from latent design  

errors, process errors, and many other  

causes. Initial failures are screened at  

manufacturer’s site through burn-in  

process. This process is called  

debugging, performing aging or  

screening.  

maintenance is effective for this type of  

failure. The timing of a relay’s wear-out  

failure can be predicted with a certain  

accuracy from the past record of uses.  

The use of a relay is intended only in the  

accidental failure period, and this period  

virtually represents the service lifetime of  

the rela

y

.  

m

63%  

Time  

γ

α

[3] Weibull Analysis  

The Weibull probability chart is a simpler  

alternative of complex calculation  

formulas

.

T

he chart provides the following  

advantages:  

(1) The Weibull distribution has the  

closest proximity to the actual failure rate  

distribution.  

(2

)

T

he Weibull probability chart is easy to  

use.  

(3) Different types of failures can be  

identified on the chart.  

Weibull analysis is often used for  

classifying a product’s failure patterns and  

to determine its lifetime. Weibull  

distribution is expressed by the following  

equation:  

(II) Accidental failure period  

The initial failure period is followed by a  

long period with low, stable failure rate. In  

this period, called accidental failure  

period, failures occurs at random along  

the time axis

.

W

hile zero accidental failure  

rate is desirable, this is actually not  

practical in the real world.  

m

–

1  

(

χ

–

γ

)

m  

m

f

(x) =

 

(

χ

–

γ

)

e  

–

α

α

where  

m

: Figure parameter  

α

: Measurement parameter  

γ

: Position prameter  

The following describes the correlation  

with the bathtub curve. The value of the  

parameter “m” represents the type of the  

failure.  

(1) When

m

< 1: Initial failures  

(2) When

m

= 1: Accidental failures  

(3) When

m

> 1: Wear-out failures  

( I )  

( II )  

( III )  

m > 1  

Time  

m < 1  

m = 1  

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Matsushita Electric Works, Ltd.  

Applications of Relays in Electronic Circuits  

REL

A

Y

D

RIVE BY MEANS OF A TRANSISTOR  

•

Connection method  

The voltage impressed on the relay is  

always full rated voltage, and in the OFF  

time, the voltage is completely zero for  

avoidance of trouble in use. (Fig. 1)  

R

Ry  

Tr  

Tr  

R

1  

Tr  

Ry  

R

2  

Ry  

(Good) Collector connection  

With this most common  

connection, opertion is stable.  

(Care) Emitter connection  

When the circumstances  

make the use of this  

connection unavoidable, if  

the voltage is not completely  

impressed on the relay, the  

transistor does not conduct  

completely and operation is  

uncertain.  

(Care) Parallel connection  

When the power consumed  

by the complete circuit  

becomes large, consideration  

of the relay voltage is  

necessary.  

Fig. 1  

•

Countermeasures for surge voltage of relay control transistor  

If the coil current is suddenly interrupted,  

a sudden high voltage pulse is developed  

in the coil. If this voltage exceeds the  

voltage resistance of the transistor, the  

transistor will be degraded, and this will  

lead to damage

.

I

t is absolutely necessary  

to connect a diode in the circuit as a  

means of preventing damage from the  

counter emf.  

As suitable ratings for this diode, the  

current should be equivalent to the  

average rectified current to the coil, and  

the inverse blocking voltage should be  

about 3 times the value of the power  

source voltage. (Fig. 2)  

Diode  

Ry  

Tr  

Take care of ASO.  

Fig. 2  

•

Snap action  

(Characteristic of relay with voltage rise  

Pulse signal (square wave)  

Non-pulse signal  

and fall of voltage)  

Unlike the characteristic when voltage is  

impressed slowly on the relay coil, this is  

the case where it is necessary to impress  

the rated voltage in a short time and also  

to drop the voltage in a short time. (Fig. 3)  

As a guide, the rising time and falling time  

are 1 ms or less.  

I

B  

Ry  

Tr Ic  

I

C  

I

B  

ON  

Ry  

OFF  

(No Good) Without snap action  

(Good) Snap action  

Fig. 3  

•

Schmitt circuit (Snap action circuit)  

(Wave rectifying circuit)  

When the input signal does not produce a  

snap action, ordinarily a Schmitt trigger  

circuit is used to produce safe snap  

action.  

2. Due to the relay coil current, the  

difference in the voltage at point P when  

T

2

is conducting and at point P when T

1

is  

conducting creates hysteresis in the  

detection capability of Schmitt circuit, and  

care must be taken in setting the values.  

3. When there is chattering in the input  

signal because of waveform oscillation,  

an RC time constant circuit should be  

inserted in the stage before the Schmitt  

trigger circuit. (However, the response  

speed drops.) (Fig. 4)  

R

1  

Ry  

Signal  

R

3  

R

2  

Tr

2  

Tr

1  

Characteristic points  

P

1. The common emitter resistor R

E

must  

have a value sufficiently small compared  

with the resistance of the relay coil. (The  

voltage impressed on the relay must not  

be greater than the excitation voltage.)  

R

E  

Fig. 4  

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Applications of Relays in Electronic Circuits  

•

Avoid Darlington circuit connections.  

(High amplification)  

This circuit is a trap into which it is easy to  

fall when dealing with high circuit  

Ry  

Ry  

technolog

y

.

T

his does not mean that it is  

immediately connected to the defect, but it  

is linked to troubles that occur after long  

periods of use and with many units in  

operation. (Fig. 5)  

Tr

1  

Tr

1  

V

CESAT

=  

About 0.7V  

V

CESAT

=  

About 0.1V  

Tr

2  

Tr

2  

GND  

(No good) Darlington connection  

(Good) Emitter connection  

(

•

Due to excessive consumption of power,  

heat is generated.)  

(T

2

conducts completely.)  

(T

1

is sufficient for signal use.)  

(

•

A strong T

1

, is necessary.)  

Fig. 5  

•

Residual Coil Voltage  

In switching applications where a  

semiconductor (transistor, UJ

T

,

e

tc.) is  

connected to the coil, a residual voltage is  

retained at the relay coil which may cause  

incomplete restoration and faulty  

operation. By using DC coils, there may  

be a reduction in; the danger of  

incomplete restoration, the contact  

pressure, and the vibration resistance.  

This is because the drop-out voltage is  

10% or more of the rated voltage, a low  

value compared to that for AC coil, and  

also there is a tendency to increase the  

life by lowering the drop-out voltage.  

When the signal from the transistor’s  

collector is taken and used to drive  

another circuit as shown in the figure on  

the right, a minute dark current flows to  

the relay even if the transistor is off. This  

may cause the problems described  

above. (Fig. 6)  

Ry  

I

O  

T

2  

T

1  

I

O

: dark current (No good)  

Fig. 6 Connection to the next stage through  

collector  

REL

A

Y

D

RIVE BY MEANS OF SCR  

•

Ordinary drive method  

•

Caution points regarding ON/OFF  

heater, the switching can occur only at  

peak values and it can occur only at zero  

phase values as a phenomenon of this  

type of control. (Depending upon the  

sensitivity and response speed of the  

relay)  

4. Accordingl

y

,

e

ither an extremely long  

life or an extremely short life results with  

wide variation, and it is necessary to take  

care with the initial device quality check.  

For SCR drive, it is necessary to take  

particular care with regard to gate  

sensitivity and erroneous operation due to  

noise. (Fig. 7)  

control circuits  

(When used for temperature or similar  

control circuits)  

When the relay contacts close  

simultaneously with an AC single phase  

power source, because the electrical life  

of the contacts suffers extreme  

shortening, care is necessar

y

.

(

Fig. 8)  

1. When the relay is turned ON and OFF  

using a SCR, the SCR serves as a half  

wave power source as it is, and there are  

ample cases where the SCR is easily  

restored.  

Ry  

R

C

S

I

GT  

Ry  

2. In this manner the relay operation and  

restoration timing are easily synchronized  

with the power source frequenc

y

,

a

nd the  

timing of the load switching also is easily  

synchronized.  

R

GK  

I

GT

: There is no problem even with more than 3 times  

the rated current.  

R

GK

: 1K ohms must be connected.  

R,C : This is for prevention of isolation point error due to  

a sudden rise in the power source or to noise.  

(dv/dt countermeasure)  

Ry  

S

3. When the load for the temperature  

control is a high current load such as a  

Fig. 7  

Fig. 8  

REL

A

Y

D

RIVE FROM EXTERNAL CONTACTS  

Relays for PC board use have high  

sensitivity and high speed response  

characteristics, and because they  

respond sufficiently to chattering and  

bouncing, it is necessary to take care in  

their drive.  

When the frequency of use is low, with the  

delay in response time caused by a  

condenser, it is possible to absorb the  

chattering and bouncing. (Fig. 9)  

(However, it is not possible to use only a  

condenser

.

A

r

esistor should also be used  

with the capacitor.)  

External contact  

R

Ry  

C

Fig. 9  

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OPYRIGHT

Matsushita Electric Works, Ltd.  

Applications of Relays in Electronic Circuits  

LED SERIES AND

P

A

RALLEL CONNECTIONS  

2. R in parallel with LED  

3. In parallel connection with relay  

1. In series with relay  

R

2  

Ry  

Ry  

Ry  

R

1  

LED  

Power consumption:  

In common with relay (Good)  

Defective LED:  

Relay operate (No good)  

Low voltage circuit:  

With LED, 1.5V down (No good)  

No. of parts: R

1

(Care)  

Power consumption:  

Current limiting resistor R

2

(Care)  

Defective LED:  

Relay operate stable (Good)  

Low voltage circuit: (Good)  

No. of parts: R

2

(Care)  

Power consumption:  

In common with relay (Good)  

Defective LED:  

Relay does not operate (No good)  

Low voltage circuit:  

With LED, 1.5V down (No good)  

No. of parts: (Good)  

ELECTRONIC CIRCUIT DRIVE BY MEANS OF A REL

A

Y  

•

Chatterless electronic circuit  

Even though a chatterless characteristic  

Notes: 1. The A, B, and C lines should be made as short as possible.  

is a feature of relays, this is to the fullest  

extent a chatterless electrical circuit,  

much the same as a mercury rela

y

. To  

meet the requirement for such circuits as  

the input to a binary counter, there is an  

electronic chatterless method in which  

chattering is absolutely not permissible.  

Even if chattering develops on one side,  

either the N.O. side contacts or the N.C.  

side contacts, the flip flop does not  

2. It is necessary that there be no noise from the coil section induced into the contact section.  

A

Ry  

N.O.  

N.C.  

Binary  

Counter  

C

B

reverse, and the counter circuit can be fed  

pulsed without a miss. (However,  

R-S-F.F  

bouncing from the N.O. side to N.C. side  

must be absolutely avoided.) (Fig. 10)  

Fig. 10  

•

Triac drive  

When an electronic circuit using a direct  

drive from a triac, the electronic circuit will  

not be isolated from the power circuit, and  

because of this, troubles due to erroneous  

operation and damage can develop  

easil

y

.

T

he introduction of a relay drive is  

the most economical and most effective  

solution. (Photo coupler and pulse  

transformer circuits are complicated.)  

When a zero cross switching  

L

Ry  

Fig. 11  

characteristic is necessar

y

, a

s

olid state  

relay (SSR) should be used. (Fig. 11)  

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OPYRIGHT

Matsushita Electric Works, Ltd.  

Applications of Relays in Electronic Circuits  

ASSURANCE OF POWER SOURCE FOR REL

A

Y

A

ND ELECTRONIC CIRCUIT  

•

Constan

t

V

oltage circuit and PC board  

pattern  

manner in which the PC board pattern is  

designed, the ON/OFF operation of the  

relay coil, lamp, etc., will exert no  

influence on the electronic circuit. This is  

just a matter of technique that is  

necessar

y

.  

Ordinaril

y

,

i

t is extremely undesirable to  

have ripple and voltage variation in an  

electronic circuit power source. This is  

naturally true also for relay power sources  

but not to the same extent as for the