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Regulation stating a type AC RCD can not be upstream from a type A RCD

Alan B

Hi

I found an EV charger today with built in type A RCD + RDC-DD connected to a type AC RCD in the consumer unit, the AC RCD is also protecting 3 other circuits including sockets. I know this is incorrect because the type AC RCD could be blinded by DC currents, but I am struggling to find a regulation to reference when providing information to the customer?

Thanks

Alan

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    I am now going to reply to Andy J. The design of modern SMPS does not have a rectifier into a smoothing capacitor because the "rules" say they must achieve virtually perfect power factor.

    But lots of devices don't have fully fledged SMPs - in the example I gave (LED lighting) it's usually far simpler and I've seen PF of 0.5 or below with some.

    Being full of electronics is not the reason for leakage is it? That is a get out of jail excuse with zero merit!

    I'm not sure I'm following your line of thought - I thought the type A requirement was to endure it tripped with a non-sinusoidal fault current (e.g. after the power electronics) - either on TT systems or on TN systems where there's significant impedance before the fault - e.g. a short to case part way along a winding - to avoid either an immediately dangerous situation (TT) or a persistent condition that may mean loss of all additional protection (TN).

    I guess there will be some leakage - power electronics usually require a bit of filtering on the mains side - but I'm not seeing the connection...

       - Andy.

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  • 0

    I am now going to reply to Andy J. The design of modern SMPS does not have a rectifier into a smoothing capacitor because the "rules" say they must achieve virtually perfect power factor.

    But lots of devices don't have fully fledged SMPs - in the example I gave (LED lighting) it's usually far simpler and I've seen PF of 0.5 or below with some.

    Being full of electronics is not the reason for leakage is it? That is a get out of jail excuse with zero merit!

    I'm not sure I'm following your line of thought - I thought the type A requirement was to endure it tripped with a non-sinusoidal fault current (e.g. after the power electronics) - either on TT systems or on TN systems where there's significant impedance before the fault - e.g. a short to case part way along a winding - to avoid either an immediately dangerous situation (TT) or a persistent condition that may mean loss of all additional protection (TN).

    I guess there will be some leakage - power electronics usually require a bit of filtering on the mains side - but I'm not seeing the connection...

       - Andy.

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