Pulsating DC RCDs

MK Sentry Pulsating DC Fault Current Sensitive RCDs
Should a waveform containing a pulsating d.c. component develop an earth fault, then it is possible that it may not be detected by an “a.c. only” sensitive RCD. For this reason, the Sentry range contains RCDs designed to be sensitive to pulsating d.c. fault currents thus maintaining the intended degree of protection.
Type B RCDs are suitable for situations where there are residual sinusoidal alternating currents, residual pulsating direct currents and smooth d.c. and a.c. residual current of various frequencies, which would not trip Type AC or A RCDs.
These situations can occur in 50Hz a.c. installations with electronic equipment, e.g. frequency converters, UPS installations, power supply unit or high-frequency power converters.