[Amps] Large Variac controlling HV power supply

[peter chadwick]

I have seen it said that it isn't a good idea because the variac regulation isn't that good. Having said that, in my youth, I worked on a tx where we had a fairly large 3 phase variac feeding a 25kV transformer, and the output was wound down a bit to give us 18kV at 4.5 amps. 

Admittedly, a choke input filter, so it wasn't wound down too far. So it should be OK.

73

Peter G3RZP
========================================
 Message Received: Oct 31 2013, 12:28 PM
 From: "Mark Beckwith" <r-emails at n5ot.com>
 To: amps at contesting.com
 Cc: 
 Subject: Re: [Amps] Large Variac controlling HV power supply
 
 I think guys have been doing this since time began.  I have two different 
 boat anchors out in the barn built exactly as you describe, both built by 
 other people (one is a bona-fide Henry industrial something-or-other).  I 
 assumed it was "best practice."
 
 73,
 Mark - N5OT
 
 
 ----- Original Message ----- 
 From: "Dave Trainor" <dave at n8zfm.com>
 To: "Amps" <amps at contesting.com>
 Sent: Wednesday, October 30, 2013 2:52 PM
 Subject: [Amps] Large Variac controlling HV power supply
 
 
 > Is there any disadvantage (other than size) in utilizing a large 30 amp 
 > variac to supply the line voltage to the HV transformer in a power supply? 
 > I have a 5000V 3A transformer that came from an industrial induction 
 > heater, and the variac from the same to control the voltage. Now both of 
 > these are large, but considering a floor roll around unit for the power 
 > supply and building the variac into the top with its steering wheel 
 > control.  Since I have both the cost is small but is there a disadvantage 
 > to doing this power wise? I expect at the current draw for legal limit I 
 > should see no voltage sag at all at 3000v since the cycle dyne induction 
 > heater the transformer came from was a 10kW unit CCS of course.
 >
 > Thanks,
 > David Trainor - N8ZFM
 >
 >
 > _______________________________________________
 > Amps mailing list
 > Amps at contesting.com
 > http://lists.contesting.com/mailman/listinfo/amps 
 
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