RCD/MCB/MCBO

Question 1

Describe the principle of operation of the three phase RCD including the test circuit

Answer 1

to detect any imbalance between the live (phase) conductors and the neutral. If the current in the live conductors doesn’t equal the current in the neutral, it indicates leakage to earth (ground) and the RCD disconnects the circuit, A test button simulates an imbalance by creating a fault

Question 2

The figures indicate the rating of an RCD for a given application 32A/30mA/AC explain the significance of each part

Answer 2

32A: Device rating
30mA: Sensitivity
AC: Type of load