The relationship between opening distance, overrun, final pressure and release force of moulded case circuit breaker? The larger the overrun, the greater the release force? The bigger the distance, the better?

Some premises:

A certain pressure should be maintained between the dynamic and static contacts of the circuit breaker. This has two main purposes:

1. Maintain the reliability of electrical contact and prevent false connection.

2. When encountering instantaneous surging short-circuit current, the electric repulsion force can prevent the contact bouncing.

Opening the upper cover of circuit breaker is necessary for measuring the distance, overrun, final pressure and release force.

[Distance]

It refers to the minimum distance between the moving contact and the static contact when the circuit breaker is in the open state.

Opening distance is mainly related to the breaking position and voltage withstanding grade of circuit breaker.

Circuit breakers with isolation function usually require that the circuit breakers have sufficient open distance.

[Override]

Say the measurement method, it may be more convenient for you to understand.

First remove the static contacts of the circuit breaker, close the circuit breaker, measure the position of the moving contacts, and get a value of 1.

Then install the static contacts of the circuit breaker, close the circuit breaker, and measure the position of the moving contacts, and get the value of 2.

It is not difficult to see that the value of 2 will deviate from the value of 1 because the "static contact cushions the moving contact".

This deviation is the overrun.

[End pressure]

Close the circuit breaker, connect a battery and a light bulb between the input and output lines.

Use a spring balance to pull the moving contacts upward to separate the static and dynamic contacts and cause the bulb to go out.

At the moment when the light bulb went out, our final pressure value appeared on the spring scale.