For the big power supply for my TH628 amplifier, 28 kV with 225 uF, do not use
a high power bleeder. It is a pulsed amplifier, so we need all the current we
can get, during each mS long pulse. There is a slow trickle bleeder (meter
multiplier) along with capacitor leakage current, which can take a long time to
discharge.
The normal bleed down is a string of very long Carborundum 2 K resistors in
series, dropped by a big Ross HV relay across the terminals, followed a couple
seconds later by another Ross HV relay that is a hard short to ground. Then, to
open the door, there are additional switches as well as big long chicken sticks
that are used to touch the output. Along with this goes a mountain of paperwork
and training to satisfy even OSHA. The relay timing is all done automatically,
so as not to drop before the HV charging supply is off. Reverse is true on turn
on.
73
John
K5PRO
> Message: 1
> Date: Wed, 29 Feb 2012 16:03:45 +0200
> From: "Alf Pousar" <alf.pousar@surffi.net>
> Subject: [Amps] Bleeders
> To: <Amps@contesting.com>
> Message-ID: <F6EDB8E3CF3845EFB10119AC490846E9@fast>
> Content-Type: text/plain; charset="iso-8859-1"
>
> Why not skip the bleeder entirely, and make a current discharge circuitry
> when the session is over.
> If the anode voltage is very high then stack some thyristors and fire them
> with opto couplers.
> So when you hit the big switch it turns off all power to the power supply,
> except for the auxillary
> circuit that keeps the draining alive and then shut off .
> Not very compicated to do and you get rid of the bleeder heat.
> Alf OH2QM
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