5.2Residual current devices terms and definitions#
The following terms relate to RCDs adapted from AS/NZS 61008.1:
Table 5.2 – Terms and definitions
| Term | Definition |
|---|---|
| Break time of the RCD | the time which elapses between the instant when the residual operating current is suddenly attained and the instant of arc extinction in all poles |
| Earth fault current | current flowing to earth due to an insulation fault |
| Earth leakage current | current flowing from the live parts of the installation to earth in the absence of an insulation fault |
| Residual current | vector sum of the instantaneous values of the current flowing in the main circuit of the RCD (expressed as rms value) |
| Residual current circuit breaker (RCCB) | a mechanical switching device designed to make, carry and break currents under normal service conditions and to cause the opening of the contacts when the residual current attains a given value under specified conditions |
| RCCB without integral overcurrent protection | a residual current operated circuit breaker not designed to perform the functions of protection against overloads and/or short circuit |
| Residual current circuit breaker with integral overcurrent (RCBO) | a residual current operated circuit breaker designed to perform the functions of protection against overloads and/or short circuit |
| Residual making and breaking capacity | a value of the ac component of a residual prospective current, which the RCD can make, carry for its opening time and break under specified conditions of use and behaviour |
| Residual operating current | value of residual current which causes the RCD to operate under specified conditions |
| Short circuit (making and breaking) capacity | Alternating component of the prospective current, expressed by its rms value, which the RCD is designed to make, carry for its opening time and to break under specified conditions |