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Ever thought about ... ?

gkenyon
I was asked a series of interesting questions this week about fault protection and overload protection for a particular application. Some of these really make you think, and the physics doesn't always lead you where you think you'd go.


Dropping out of all this, was me pointing out something interesting which I wonder whether it's ever crossed the minds of contributors to this Forum ... so here goes.


Ever thought about what, in typical UK installations, protects the electronics in a plug-in [to a standard BS 1363-2 socket-outlet] phone charger / wall-wart type power converter against:

(a) Fault current (consider both cases of L-N and L-PE); and

(b) Overload current ?




Parents
  • 0
    So, this is really pertinent ... a fault on the mains side, what sort of let-through energy should be considered ...

    ... in the UK use-case this is ???

    ... in most other countries' use-cases, this is ???

    As a random starting point, I'd suggest the let-though of an MCB for, let's say for the sake of debate, 6kA fault - so

    • UK - say a B32 - 45,000 A²s

    • Euro - say a C16 - 42,000 A²s, or a C20 - 55,000 A²s


    at 6kA we have no guarantees a RCD will be fast enough to reduce the energy let-through.


      - Andy.
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  • 0
    So, this is really pertinent ... a fault on the mains side, what sort of let-through energy should be considered ...

    ... in the UK use-case this is ???

    ... in most other countries' use-cases, this is ???

    As a random starting point, I'd suggest the let-though of an MCB for, let's say for the sake of debate, 6kA fault - so

    • UK - say a B32 - 45,000 A²s

    • Euro - say a C16 - 42,000 A²s, or a C20 - 55,000 A²s


    at 6kA we have no guarantees a RCD will be fast enough to reduce the energy let-through.


      - Andy.
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