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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 ?




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  • 0
    gkenyon:
    mapj1:


    In good designs by reputable makes the PCB will often have a link designed to melt, or the inrush resistor is a fusible one. The glued case should be strong enough to contain all the flying parts during the highest energy operation of these mechanisms.

     


    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 ???




    I'm still slightly lost as to what the actual question is.  A single USB charger shouldn't draw more than about 15W (0.065A) under any circumstances.  But you seem to be asking what will protect against some massive power surge, under some unspecified conditions.


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  • 0
    gkenyon:
    mapj1:


    In good designs by reputable makes the PCB will often have a link designed to melt, or the inrush resistor is a fusible one. The glued case should be strong enough to contain all the flying parts during the highest energy operation of these mechanisms.

     


    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 ???




    I'm still slightly lost as to what the actual question is.  A single USB charger shouldn't draw more than about 15W (0.065A) under any circumstances.  But you seem to be asking what will protect against some massive power surge, under some unspecified conditions.


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