[Amps] Bleeder Resistor Inquiry

[Will Matney]

David,

I did'nt catch the piece about a variac as I seen the one from Joe. Well, it's according the the maximum open circuit voltage, across how many ohms, at how much current, to determine the wattage. That is as long as the voltage rating is not exceeded. If this was a surpluss resistor, or a used one, it's possible that it had been damaged previously. One thought would be to double check the resistance. Seems to me something similar happened before with a resistor whos value was way off from its marked value. This was a new resistor I think, and am not sure but seems like Hal Mandel had a problem with it. Seems like Ohmite made it too!

Best,

Will

*********** REPLY SEPARATOR  ***********

On 4/24/05 at 12:24 PM David C. Hallam wrote:

>If I read Mike's original post correctly, he stated that he held the
>voltage
>to 4KV with his variac.  Therefore, he should have had 40 mA draw by the
>bleeder resistor which is equal to 160W dissipation.  That should have not
>cooked a 225W rated resistor.  Maybe the resistor had some shorted turns or
>his voltage reading was incorrect.
>
>All the comments about safety with bleeder resistors are correct, but don't
>answer the question as to what might have cooked his bleeder.
>
>David
>KC2JD
>
>-----Original Message-----
>From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com]On
>Behalf Of aborg
>Sent: Sunday, April 24, 2005 9:44 AM
>To: Amps Amps
>Subject: [Amps] Bleeder Resistor Inquiry
>
>
>I am currenty building a HV Power Supply using a
>4800vac pole pig, 40uF 5kv oil filled cap , 10kv PIV
>rectifier board, 20 amp variac and a 100k 225watt
>bleeder.
>
>The initial power up started well without the bleeder
>connected to the circuit after 30 min burn-in no
>problems. Discharged the circuit and added the 100k
>bleeder and 5 mins the bleeder starts to smell and the
>exterior paint starts to bubble. Shut it down and
>examined the circuit, all seem accurate.
>
>Question : Is my bleeder to small ?
>
>P.S. : The variac was set at 4KV at all times.
>
>Mike-KK4MS
>a_borg at yahoo.com
>
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