What do the leakage circuit breakers AC type, A type, and B type mean?

Type AC leakage circuit breaker

The AC type leakage circuit breaker is developed and designed for the power frequency sinusoidal leakage current, and can reliably protect the sinusoidal leakage current that is suddenly applied and slowly rising.

Type A leakage circuit breaker

The A-type leakage circuit breaker and the AC-type leakage circuit breaker are basically the same in the working principle (measure the leakage value through the zero-sequence current transformer), but the magnetic characteristics of the transformer are improved. It guarantees tripping under the following conditions:

(a) Same as AC type.

(b) Residual pulsating DC current.

(c) The residual pulsating DC current is superimposed with a smooth DC current of 0.006A.

Type B leakage circuit breaker - (more difficult to do)

Type B leakage circuit breaker can reliably protect sinusoidal AC signal, pulsating DC signal and smooth signal, and has higher design requirements than type A leakage circuit breaker. It guarantees tripping under the following conditions:

a) Same as type A.

b) Residual sinusoidal alternating current to 1000 Hz.

c) The residual AC current is superimposed on a smooth DC current of 0.4 times the rated residual current

d) The residual pulsating DC current is superimposed with 0.4 times the rated residual current or a smooth DC current of 10mA (whichever is greater).

e) Residual DC currents produced by the following rectifier circuits:

- For 2-pole, 3-pole and 4-pole earth leakage circuit breakers, two half-wave bridge connections from line to line.

- For 3-pole and 4-pole earth leakage circuit breakers, 3 half-wave star connections or 6 half-wave bridge connections.

Various types of leakage circuit breakers can only effectively protect the corresponding leakage signals. In circuits containing a large number of electronic equipment and frequency conversion equipment, because the leakage signals contain pulsating DC signals, AC-type leakage circuit breakers cannot effectively protect the circuit. , then you should choose the leakage circuit breaker for pulsating DC signal - type A leakage circuit breaker.