Technical parameters of residual current circuit breaker

The main operating performance parameters include: rated residual current operating current, rated residual current operating time, and rated residual current non-operating current. Other parameters include: power supply frequency, rated voltage, and rated current.

① Rated Residual Current Operating Current: The current value that will cause the residual current device (RCD) to trip under specified conditions. For example, a 30mA RCD will trip and disconnect the power supply when the applied current reaches 30mA.

② Rated Residual Current Operating Time: The time from the sudden application of the rated residual current operating current until the protected circuit is disconnected. For example, a 30mA × 0.1s RCD will take no more than 0.1s from the current reaching 30mA until the main contacts separate.

③ Rated Residual Current Non-Operating Current: The current value at which the RCD will not trip under specified conditions. Generally, this should be half of the residual current operating current. For example, an RCD with a residual current operating current of 30mA should not trip when the current reaches below 15mA; otherwise, its high sensitivity may lead to false tripping, affecting the normal operation of electrical equipment.

④ Other parameters, such as power supply frequency, rated voltage, and rated current, should be compatible with the circuit and electrical equipment used when selecting a residual current device (RCD). The RCD's operating voltage must be compatible with the normal fluctuation range of the power grid. Excessive fluctuations will affect the normal operation of the RCD, especially for electronic products, which may fail to operate if the power supply voltage is lower than the RCD's rated operating voltage. The RCD's rated operating current must also match the actual current in the circuit. If the actual operating current exceeds the RCD's rated current, it will cause overload and malfunction.