[ARC5] Need Help with Variac Diagnosis

[Dennis DuVall]

Jeep,

The only time 'Ive experienced “inrush” (or whatever the phenomenon is) problems was at my last QTH in Maryland where I was working off a very “stiff” primary source.  Four hundred amp service and a T-368 located about 6 feet away from the main breaker panel.  About once a week I would kick the breakers (both of them) on the T-368 on PTT and about once a month I would kick the 30 amp breaker on the main distribution panel as well.  I attributed this happening on those (rare) occasions where on key up the plate xfomer in the T-3 had been left in a magnetized  part of it's hysteresis loop, and then on a key-down which just happened to hit the incoming AC cycle at or near a peak charging voltage of the opposite polarity.  The phenomenon never seemed do any damage and when I moved to a different location with a physically much longer AC feed I never experienced the problem again.  Go figure...

Dennis D.  W7QHO
Glendale, CA

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> On Feb 19, 2015, at 4:53 PM, DSP3 <jeepp at comcast.net> wrote:
> 
> Interesting, all.  I use a 220v/20A rated Variac adjust the nom. 120v line voltage going to a T-368.  I have never had a trip and it's on a 15A breaker.    I am surprised by all this.   Perhaps the impedance of the 220v breaker is higher than a 115v unit?  Oh well.....  As an aside, I found that all voltages fall into "book value" by operating the T-368 at 115v.
> 
> Jeep - K3HVG
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