I'm designing a variable frequency drive, so rectifying and filtering a
    120 volt AC wave. This results in about 160 volt's DC. When I turn it
    off I bleed the voltage off through a couple of 1/2 watt 100k ohm
    resistors. This seems to take for ever to bleed.

How big are your filter caps?  The time constant is RC
(megohms*microfarads), so 1000uF should take about 100 seconds to bleed off
with 100k.  You could keep adding additional 1/2W 100k resistors (in
parallel) until the bleed-off is as fast as you want.


    Most bleeder resistors I have ever seen are usually in the MegaOhm
    range.  For example, I use 1 megaohm bleeders on a polypropylene pulse
    capacitor MMC, that pulses 15,000 volts input to a Tesla coil through
    a spark gap (LRC) - to prevent the caps killing me if I accidentally
    go near them in any short space of time after turning off the power
    supply ;) IME, 100k seems too low a resistance for a bleeder.

Yeah, but you're probably dealing with nano-F instead of milli-F.  The
bleeder resistor matches up with the capacitance, more or less.  Switching
power supplies (5-12V) can have "bleeder" resistors designed to draw 100mA
or more, just to keep the supply in regulation when otherwise "unloaded."

BillW

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