IMPORTANCE OF RCCB:
Residual Current Circuit Breakers are aimed at protecting an individual from the risks of electrical shocks and fires that are occurred due to faulty wiring or earth faults.
RCCB is particularly useful in situations where there is a sudden earth fault occurring in the circuit.
For Example, A person accidentally comes in contact with an open live wire in the circuit.
In such situation, in absence of an RCCB in the circuit, an earth fault may occur and the person is at the risk of receiving an electrical shock.
HOW DOES IT WORK:
It working based on Kirchhoff’s Current Law, the incoming current in a circuit must be equal to the outgoing current from that circuit.
In case of an earth fault, the current finds a passage to earth through accidental means (such as accidental contact with an open wire etc.). As a result, the returning current from neutral is reduced. This differential in the current is also known as “Residual Current”.
RCCB is designed such a way that it continuously compares for difference (residual current value) in current values between the live and neutral wires. Any small change in the current value on account of such event would trigger the RCCB to trip off the circuit.
The basic operating principle lies in the Toroidal Transformer shown in the diagram containing three coils. There are two coils say Primary (containing line current) and Secondary (containing neutral current) which produces equal and opposite fluxes if both currents are equal.
The Toroidal transformer, sensing coil and relay together is known as RCD – Residual Current Device.