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Re: resistors
From: John H. Couture [SMTP:couturejh-at-worldnet.att-dot-net]
Sent: Wednesday, November 12, 1997 6:58 PM
To: Tesla List
Subject: Re: resistors
At 02:41 PM 11/12/97 +0000, you wrote:
>
>From: Peter Electric [SMTP:elekessy-at-macquarie.matra-dot-com.au]
>Sent: Wednesday, November 12, 1997 1:33 AM
>To: Tesla List
>Subject: Re: resistors
>
>Tesla List wrote:
>
>> rom: Gary Lau 11-Nov-1997 1428 [SMTP:lau-at-hdecad.ENET.dec-dot-com]
>> Sent: Tuesday, November 11, 1997 12:35 PM
>> To: tesla-at-pupman-dot-com
>> Subject: Re: resistors
>>
>> >snip
>
>I am using fairly large ferrite core chokes (around 30mH) with a string
>of 3 by 1K, 10Watt resistors in each leg. Transformers are 15Kv 60Ma.
>These used to run stinking hot with the forced air quench gap I ran
>previously but something interesting happens with my new sync rotary. If
>the rotary is not phased right, the safety gap sparks and the resistors
>run very hot. If the sync is spot on, the safety gap stops sparking and
>the resistors run noticeably cooler, but the output streamers get
>longer!
>
>It would seem from this that much of the heating in the resistors is
>power being reflected back into the transformer.
---------------------------------------------------------
Gary, Peter -
If you have a scope it would be interesting to check the waveforms. The
rotary, properly phased, should show quench at the first notch. This would
indicate the enegy (power x seconds) is being dissipated in the longer
streamers.
The forced air gap should show several transfers and notches before
quenching. This condition would indicate the energy is being reflected back
to the primary circuit and would be causing the overheating of the resistors.
The probe for voltage waveforms could be a 1000 ohm resistor across the
scope leads held a safe distance from the coil.
John Couture