[Milsurplus] Negative Lead Filtering

[k2cby at optonline.net]

I assume from Mark's post that he is talking about a high voltage power
supply.

So far as I know, the only reason to use negative lead filtering is to avoid
the need for a choke with a high voltage rating.

Operationally, the power supply will be no different from one where the
choke is in the positive leg.

There is a safety concern, however. If the choke should fail, creating an
open circuit in the negative leg, everything between the input side of the
failed choke and the transformer center tap will immediately rise to
negative high voltage. The negative poles of the filter capacitors - and
everything else in the negative leg -- should therefore be insulated. What's
worse, the center tap lead of the power transformer (which was never
designed to see high voltage) may short to the frame, making the entire
chassis lethal. 

/Miles, K2CBY

 

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