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Re: [Amps] HV SAFETY QUESTION

To: amps@contesting.com
Subject: Re: [Amps] HV SAFETY QUESTION
From: "David A. Pruett" <k8cc@comcast.net>
Date: Fri, 23 Jan 2004 18:47:22 -0500
List-post: <mailto:amps@contesting.com>
At 06:35 PM 1/22/04 -0700, Jim Homer wrote:
I have an old Ham acquaintance that can testify to 8 inches of a
medium-weight plastic-handled screwdriver being reduced in length by about 3 inches while using it to ground a 40 ufd 6.6 kv HV power supply that had an open bleeder string.

I see a lot of power supply designs where the HV metering circuit is connected across a relatively small (~500 ohms) power resistor at the low end of the bleeder string. This has the advantage of economy in avoiding the need for HV meter multiplier resistors.


I would suggest that a safer approach is to have the metering circuit separate with it's own string of resistors. This way, if the bleeders open, the metering current will still discharge the filter capacitors. It *MAY* take a while (depending on the impedance of your HV meter circuit) but it will discharge. This approach also has the safety advantage that the HV meter still works if the bleeder opens.

Dave/K8CC


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