RCCB stands for Residual Current Circuit Breaker.
Core Function: Its main function is to detect leakage current in a circuit and, in the event of leakage (such as electric shock or current leakage to ground due to equipment insulation failure), quickly cut off the power supply, thereby protecting personal safety or preventing electrical fires.
Working Principle:
Monitoring Current Balance: The RCCB contains a zero-sequence current transformer that simultaneously monitors the current in both the live wire (L) and the neutral wire (N).
Normal State: When the circuit is operating normally, the current flowing into the live wire and the current flowing out of the neutral wire are equal in magnitude and opposite in direction, with a vector sum of zero. The RCCB does not trip.
Leakage State: When leakage occurs (e.g., electric shock or short circuit to ground), some current flows through the ground, causing the current in the live wire and neutral wire to become unbalanced (a difference appears, i.e., “residual current”).
Power cut-off: Once the detected residual current exceeds the set action value (usually 30mA for household use), the RCCB will automatically trip and cut off the circuit in a very short time (usually less than 0.1 seconds).
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