RSIDUAL CURRENT CIRCUIT BREAKER (RCCB)

  1. Current operated ELCB (or RCCB) – RCCB is a device that is used in electrical circuit that trips circuit when current becomes imbalance between phases & neutral. This imbalance may be due to any reason either by touching live wire by a person or due to imbalance load between phases etc.

Working principle –It consists of a sensing coil, fixed & moving contacts. The inside RCCB the phase & neutral wires are wound on amain coil. Also a sensing coil is also wound on this coil. The function of sensing coil is to detect the emf induced in the main coil. In case of single phase load, same current flows in bothphase & neutral, hence same emfs are induced in the main coil by phase & neutral wire are in opposite direction  so no resultant emf is induced in the main coil.

When an earth fault occurs in the equipment, current in phase wire will not be same in neutral wire as some part of current flows as a leakage current. So, due to this difference current in phase & neutral wire, a resultant emf is induced in the coil which is sensed by the sensing coil which actuates the tripping mechanism & trips the circuit.

SELECTION OF RCCB

  • It should be capable to carry the rated current of load,
  • Check RCCB is required for single phase or 3 phase load.
  • Check number of poles – DP & 4P where

DP = Double Pole which means phase & neutral wires will be connected,

4P = Fore pole which means 3 phases & a neutral will be connected.

  • Fault current rating (in mA) on which relay should trip/interrupts the faulty circuit e.g. 30mA, 100mA & 300mA.

Ex – 40A DP RCCB with 30mA fault current.

CURRENT RATING OF RCCBs

30mA DP –

A typical range of single phase – RCCB – 6A, 10A, 16A, 20A, 25A, 32A, 40A, 63A.

100mA DP –

A typical range of single phase – RCCB – 6A, 10A, 16A, 20A, 25A, 32A, 40A, 63A.

300mA DP –

A typical range of single phase – RCCB – 16A, 20A, 25A, 32A, 40A, 63A.

30mA 4P –

A typical range of Three phase – RCCB – 6A, 10A, 16A, 20A, 25A, 32A, 40A, 63A.

100mA 4P –

A typical range of Three phase – RCCB – 16A, 25A, 32A, 40A, 63A.

300mA 4P –

A typical range of Three phase – RCCB – 16A, 25A, 32A, 40A, 63A.