Tap switch circuit load details

 

 

Touch the switch circuit load details. I hope it can be convenient for you to use.

 

The type of tap switch circuit load

 

1. Resistance load

 

Resistance load refers to the power factor (COS φ = 1) under resistance load only. The rating mark of the switch indicates the current capacity when AC is used.

 

2. DC load

 

In the case of DC load, different from AC, because the current direction is constant, the arc duration is longer under the same voltage.

 

3. Incandescent lamp load

 

When the lamp is on, after the switch is set to on, because the impact current flowing in the instant is 10-15 times of the normal current, contact adhesion may occur. Please consider the transition current when selecting the switch.

 

4. Inductive load

 

In the case of inductive load (relay, solenoid, buzzer, etc.), the arc caused by reverse potential will be generated, which may cause contact failure. Therefore, it is recommended to insert appropriate spark elimination circuit (refer to the figure below).

 

5. Motor load

 

When the motor starts, the starting current flowing through is 3-8 times of the normal current, so the contact adhesion may occur. Depending on the type of motor, but the current flowing is several times of the nominal current, so please refer to the values shown in the table below when selecting the switch. In addition, when the motor rotates reversely, it is necessary to consider that when the on-off-on switch is used, the multiplication current (starting current + reverse starting current) should be avoided.

 

In the case of reverse rotation, the current flowing is about 2 times of the starting current. In addition, due to the influence of time delay, arc short-circuit (circuit short-circuit) may occur between poles during switching when it is used for load with transition phenomenon, such as reverse rotation operation of motor, or different pole switching, etc. Please pay attention when using.