Technical Terminology & Cautions for Use

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AECTB36E 201510-T

TECHNICAL NOTES ON ELECTRICAL CHARACTERISTICS

CAUTIONS IN A CIRCUIT

1) The snap-action switch is designed for AC operations. While it

has small contact gaps and no arc absorber, it may be used for

low-capacity DC operations.

Please refer to the rating of each products

2) For applications with very small switching voltage or current,

choose the low-level load type (Au contact).

3) When selecting a contact type of a snap-action switch to be

used for low-level load switching, the following should be noted.

Silver contacts’ surfaces are prone to be oxidized and form a

sulfide film. The switch operates with no problems at the

beginning of use. However, as the contact surfaces develop films

with time, the film may not be broken by the switching operation,

causing a conduction failure. Therefore, please choose the Au

contact type for switching a load of 0.1 A or below.

4) Application to Electronic Circuits

• The snap-action switch contacts can sustain bounce or chatter

when closed. Bounce or chatter can cause noise or pulse count

errors when the snap action switch is used in electronic circuits.

• If contact bounce or chatter poses problems in the vicinity of

the OP and RP, use a suitable absorption network, such as a C/

R network.

5) Check the surge current, normal current and surge duration.

6) Contact resistance given in performance specifications is

measured with a voltage drop method using 6 to 8 V DC, 1 A

(except for low-level load type). Contact resistance across COM

and NC terminals is measured in the free position, while contact

resistance across COM and NO terminals is measured in the

total travel position.

7) Ratings are measured under the following conditions:

Inductive load: Power factor 0.6 to 0.7

Time constant: 7 ms or less (DC)

8) To prevent contact welding failure, be sure to use a serial

resistance for each capacitive load.

9) If snap-action switch operation is synchronized with the AC

supply phase, this may cause: shortened electrical life, contact

fusion failure, contact transfer, or other reliability problems.

Small current and voltage application range (Au contact)

500

100

50

5

2

1

4

8

12

16

20

24

10

DC voltage (VDC)

1) Contact protection is recommended when snap-action

switches are used in an inductive load circuit.

2) Do not connect the

contacts on individual

switches to different

type or different poles of

the power supply.

Examples of power

supply connections

(connection to different

poles)

Example of wrong

power supply

connection (connection

to different poles of

power supply)

This may lead to mixed

DC and AC.

3) Avoid circuits which

apply voltage between

contacts. (This may lead

to mixed deposition.)

Circuit diagram

Cautions for use

Contact for snap-action switch

(1) r = more than 10

Ω

(2) In an AC circuit

Impedance of R is to be slightly smaller

than impedance of r and c.

Contact for snap-action switch

Can be used for both AC and DC.

Impedance of r is nearly equal to

impedance of R.

C: 0.1

μF

Contact for snap-action switch

(1) For DC circuits only.

Contact for snap-action switch

Can be used for both AC and DC.

rc

R

r

c

R

R

diode

R

ZNR

Varistor

PL

Wrong

Solenoid load

Lamp load

PL

Right

Solenoid load

Lamp load

Load connected to same pole

L

Load

L

Load

AC

DC

Wrong

Wrong

L

100V

200V