RCCB- Residual Current Circuit breaker
Connection Diagram and Working Principle.

  1. Residual current circuit breaker(RCCB).
  2. RCCB connection diagram.
  3. RCCB Working principle.
  4. Types of RCCB.
  5. Why RCCB is used.

1- Residual Current Circuit Breaker (RCCB):

RCCB is used for leakage current sensing. It is an electromechanical protective device which is used for prevention of leakage current, earth leakage. It is also provides protection against electrical shock.

It is very important for protection against earth fault because the earth fault may be cause for system heating, short circut , burning or shock. After sensing earth fault or shock then it will tripped and circuit will be open. So many reason is available for using RCCB.

2- RCCB Connection Diagram.

Residual current circuit breaker(RCCB): types and their functions.

3- Working principle of RCCB:

Basic principle:

The basic function of RCCB is the same of Kirchhoff current law.

  • If incoming current vector sum and outgoing current vector sum is same then in this condition, RCCB will not be tripped.
  • If incoming current vector sum and outgoing vector sum is not same then it shows that current is leakage condition and RCC will be tripped.
RCCB: types, connection diagram and working principle.
Working Principle:

It works on current basis. It detects leakage current. Phase outgoing current and neutral incoming current should be equal during without fault. When any phase touches with body then phase current will not be receive on neutral end point resultant phase flowing current and receiving current on neutral will not be equal. In that situation the RCCB will monitor preset value of leakage current like as 30 mA,100mA,300mA if the leakage current is more than preset value then it will interrupted the live circuit. In this way the equipment will be safe.

4- Types of RCCB:

  1. According to Phase:
    • Double Pole RCCB
    • Four pole RCCB
  2. According to Pole:
    • Double Pole RCCB
    • Four pole RCCB
  3. According to current ratings:
    • 16A, 25A, 32A, 40A, 63A
  4. According to leakage current:
    • 30ma, 100ma, 300ma

5- Why RCCB is used:

In domestic and industries many equipment and lighting circuits are used. Equipment live wire may be connect with metal body then the current will be pass on body. If any human touches equipment then he will get shock. So this condition is very dangers to the human. Other reason is due to leakage current, system may be heat or fire case in system.
So RCCB is used for equipment and human safety.

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