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A quote from technical literature on MK's site:
3. Types of fault current.
In an installation different types of fault current can occur. MK offer RCDs to suit these conditions.
Sentry Type AC RCDs are suitable for situations where there are residual sinusoidal alternating currents,whether applied suddenly or rising slowly. This is the most commonly used type of RCD in the UK.
Sentry Type A RCDs (i.e. pulsating d.c. fault current sensitive) are suitable for situations where there are residual sinusoidal alternating currents, whether suddenly applied or slowly rising.
These situations can occur with the use of semiconductor devices in modern electrical and electronic equipment, such as computers, printers, plotters, televisions, video cassette recorders and hi-fi equipment, is growing.
Such devices may result in the normal sinusoidal a.c. waveform generated by the mains electrical supply being ‘modified’. for example, the waveform may be rectified or, as in asymmetric phase control devices, the waveform may be chopped.
The resulting waveforms are said to contain a pulsating d.c. component
as illustrated below.
Pulsating d.c. 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.
It lists "residual sinusoidal alternating currents" for both type AC and type A, but makes no mention in the blurb for Type A (other than at the beginning) of the pulsating DC fault current.
When you get to Type B, it mentions "residual sinusoidal alternating currents, residual pulsating direct currents and smooth d.c. and a.c. residual current of various frequencies"
Should it be as follows:
Type AC: residual sinusoidal alternating currents.
Type A: residual sinusoidal alternating currents and residual pulsating direct currents.
Type B: residual sinusoidal alternating currents, residual pulsating direct currents and smooth d.c. and a.c. residual current of various frequencies.???
Please help, for having read MK's tech blurb, I am now confused as to what I thought was the truth......
While I'm here, do ALL PV installs NEED Type B RCD's??
And what about sockets for charging EV's??
3. Types of fault current.
In an installation different types of fault current can occur. MK offer RCDs to suit these conditions.
Sentry Type AC RCDs are suitable for situations where there are residual sinusoidal alternating currents,whether applied suddenly or rising slowly. This is the most commonly used type of RCD in the UK.
Sentry Type A RCDs (i.e. pulsating d.c. fault current sensitive) are suitable for situations where there are residual sinusoidal alternating currents, whether suddenly applied or slowly rising.
These situations can occur with the use of semiconductor devices in modern electrical and electronic equipment, such as computers, printers, plotters, televisions, video cassette recorders and hi-fi equipment, is growing.
Such devices may result in the normal sinusoidal a.c. waveform generated by the mains electrical supply being ‘modified’. for example, the waveform may be rectified or, as in asymmetric phase control devices, the waveform may be chopped.
The resulting waveforms are said to contain a pulsating d.c. component
as illustrated below.
Pulsating d.c. 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.
It lists "residual sinusoidal alternating currents" for both type AC and type A, but makes no mention in the blurb for Type A (other than at the beginning) of the pulsating DC fault current.
When you get to Type B, it mentions "residual sinusoidal alternating currents, residual pulsating direct currents and smooth d.c. and a.c. residual current of various frequencies"
Should it be as follows:
Type AC: residual sinusoidal alternating currents.
Type A: residual sinusoidal alternating currents and residual pulsating direct currents.
Type B: residual sinusoidal alternating currents, residual pulsating direct currents and smooth d.c. and a.c. residual current of various frequencies.???
Please help, for having read MK's tech blurb, I am now confused as to what I thought was the truth......
While I'm here, do ALL PV installs NEED Type B RCD's??
And what about sockets for charging EV's??
