[Amps] INRUSH

[R.Measures]

On Dec 26, 2004, at 1:37 PM, DF3KV wrote:

>
> ----- Original Message -----
> From: "Harold B. Mandel" <ka1xo at juno.com>
> To: <dpipes at earthlink.net>
> Cc: <Amps at contesting.com>
> Sent: Sunday, December 26, 2004 10:02 PM
> Subject: [Amps] INRUSH
>> The Inrush Protector product you mention in your previous post is
> exactly
>> the ticket.
>>
>> I just finished a commercial television transmitter repair job
>> where the owners have replaced 300+ diodes in the last
>> quarter and were becoming frantic. The 46KW UHF
>> station had no inrush protection scheme for the Anode
>> Supply (3-Phase, 480V, 15KV @ 12 amperes).
>>
>> It took a Crouzet Timer, a P&B 30-amp control relay
>> and 2 Square-D 100 amp contactors with twelve 400 watt,
>> 6.8 ohm resistors to solve. The resistors don't even
>> get hot when she steps and no more blown diodes.
>>
>> By the way, the filter is 2 units of 194uF @ 30KV
>> and weigh around 200 pounds each.
>
> in my opinion the filter bank is too much oversized for a 3-phase
> powersupply
> even when no bridge rectifier  is used and that caused the problem
> with the diodes.

I agree.  Also:
1.  If step-start resistors do not get moderately hot during start-up, 
they are over-sized.
2.  30kV filter caps in a 12kV supply are not logical.


> With a commercial tv transmitter I would expect it being on the air
> around the clock with rare occasions were the power supply is being
> switched
>
> 73
> Peter
>
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>

Richard L. Measures, AG6K, 805.386.3734.  www.somis.org