Lou Tiberia wrote:

>Hello,
> 
>I'm hoping someone that's knowledgeable about surge protectors can answer this:
> 
>I opened the case of an industrial power strip (PDU) to see what's in it.
>Basically, the PCB inside just has the Line, Ground, and Neutral wires soldered onto the PCB, and then 3 other matching L-G-N wires soldered on to continue on to the receptacles. 
>On the PCB, in parallel to thse main L-G-N traces, are 3 surge protection circuits, each circuit consisting of 1 fuse, 1 thermal cut off (TCO), and 3 MOVs. 
>All 3 surge circuits connect in the classic arrangement of several MOVs in parallel placed across each of the three conductive pairs; L-N, L-G, and N-G.
> 
>I understand the arrangement of MOVs, thermal cut offs (TCOs), and fuses, but have 2 questions:
> 
>1)
>The fuses are 2AG-224 8A 125V Fast-Acting. 
>Why was an 8A fuse picked? 
>Since the fuse is there for the case when the MOVs have failed closed and the surge circuit is always drawing current, wouldn't a lower rated fuse be preferred?
>  
>
What was the rating of the power strip?

> 
>2)
>The traces in the surge circuits are anywhere from .1" to .3" wide. 
>The PDU is rated 20A.
>Shouldn't the traces be at least .5" wide?
>  
>
I think you will find that these traces are 2ounce copper, which have a 
rating 4x normal 1oz copper; they can handle 20A.


>For example, what happens if a surge strikes while the PDU has equipment plugged in that is drawing 18A? 
>Wouldn't that burn out or blast a trace path?
>  
>
yes, it will. No matter how heavy the trace is, it won't be enough. It 
will balast a path anyway.

--Bob


> 
>Thank you,
>Lou
> 
>
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