Tyler,
The only Pole Pig we killed at kVA was a brand new 14.4kv/25kva unit still sitting on the skid from T&R. We had connected a capacitor in series (if I remember correctly) and were drawing long arcs and burning boards. Draw was in the 80-100a range until the pressure relief opened and oil started blowing out :(
BrianB
> On Jan 4, 2019, at 4:07 AM, David Rieben <drieben@xxxxxxx> wrote:
>
> Tyler,
>
> Wow! Although $700 may be a decent deal for a 25 kVA pig these days, it ain’t cheap at all, at least not to me! Especially when it dies on you so soon after the purchase! Can you provide any details on the capacitor that you were using (uFd, kV rating) and whether you were placing the capacitor in parallel with the Jacobs ladder rails or in series between the transformer bushings and the Jacobs ladder rails?
>
> Like I said, I have let the magic smoke out of a couple of smaller transformers in the past by simply seriesing the hv output of the pole pig’s bushings through a capacitor. I found that if the capacitance was in the correct range, it would form a near resonance with the transformer’s hv output and allow the power arc to drawn out to several feet before breaking, as opposed to mostly 12” to 18”, at best, before breaking without the capacitor. I should mention that my ballast allows about 100 amps to be drawn when shorted across a 240 volt AC source and when I applied the line voltage to my transformer, it would draw upwards of around 80 to 90 amps (w/out the capacitor). Also, with the correct sized capacitor, the power arc is much louder and the current draw INCREASES (and can momentarily peg out my 150 amp ammeter, through my same ballast!) with increased arc length, as opposed to DECREASING current draw with arc length increase without the capacitor!
>
> Your experience, as well as my past experiences with a smaller (5 kVA) pole pig and a 3 kVA PT, is starting to make me reconsider this practice (google “arczilla”) with my own 25 kVA, 14.4 kV transformer! Maybe the ferro-resonance that Jan mentioned is what’s happening here and may not be healthy practice for any pole transformer?
>
> David
>
>
>
> Sent from my iPhone
>
>> On Jan 3, 2019, at 2:29 PM, Terry Oxandale <toxandale@xxxxxxxxxxxxx> wrote:
>>
>> I know we would see static charges develop during oil filtering/filling, but these were very short-lived changes, but still enough to get your attention.
>> On Thursday, January 3, 2019, 1:07:31 PM CST, Teslalabor <teslalabor@xxxxxxxxxxx> wrote:
>>
>> How should this be possible? If there is any tiny charge, it surely is
>> not dangerous?
>>
>>
>>> Be sure to ground all terminals for a few minutes before disassembling. S
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