[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Pole Pig Wiring

Original poster: "Gerald  Reynolds" <gerryreynolds@xxxxxxxxxxxxx>

Thankyou David,

I might try to ohm out this thing, now that I'm curious. Do you know if the core is tied to the case internally???

I just ohmed it out. The LV windings are indeed connected to the center post (and the two outer posts) and the resistance is too small to for a 2 probe measurement. I will run a current source thru the LV windings and measure the voltage drop. This will tell me if the windings are in series or parallel (I hope in series for 240V operation). Do you know if for 120V operation the LV windings are connected to the two outside posts and the center post is internally unconnected??? The primary and secondary windings are isolated from case. I just cant tell what is done to the core.

Finished the resistance measurements LV1 is 30 milli ohms and LV2 is 20 milli ohms and they are indead in series and the center tap is connected to the center post.. LV2 must be an inner winding cuz of the lower resistance. The HV windings (bushing to bushing) measures 180 ohms. A little better than an NST?? It is hard to imagine much of any temp rise in the pig since with 50 amps in LV and .83 amps in HV. The I2R loss is 250 watts (running a 5KVA pig at 12KVA). Dont know what the core losses would be.

Gerry R

Original poster: "David Rieben" <drieben@xxxxxxxxxxxxxxx>

Gerry,

I don't think that the center secondary low terminal of a pig is internally
connected to the core although the untility company will often externally
connect a grounding buss strap from the center terminal to the case of the
external tank. That's the reason that you can run a pig with 240 volts input
into the secondary low voltage terminals of the pig with one side of the
240 volts ballasted through a welder. If the center terminal was already
grounded, you would be unable to ballast  the input properly. For that
reason, this terminal is left unconnected.

David