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Quick Question someone asked me ..... If a source phase is lost on an oil filled three phase transformer (NO LOAD CONNECTED), will this eventually damage the transformer? I say no, the transformer can remain energized indefinately with no concerns

Thanks for everyones advice, I am going check the level and add oil if necessary and pull another oil sample .... and take it from there. There unit doesn't have radiator valves. The manufacturere seems to think the level is low as well. At 25degC, the oil should be midway between the top manifold.

The oil test results are all acceptable (ACID .020), and the unit has an excellent history. I just wish I knew if a 140degF exterior (peak) temp was cause for concern. the definition of temp. rise is ""the average temperature of the windings and insulation above the existing ambient...

Thanks for the replies. Ambient is about 40 degF That's what has me puzzled, the transformer is setting level, but the 2 other radiators are circulating normal. the liquid level gauge is between the "25deg" and "LO" range. Your right, it does sound like it is low on oil, perhaps a topping off...

We have a 1986 vintage Westinghouse 2000KVA 23kV-480V 65 deg C rise transformer showing some interesting characteristics under a thermal inspection (please note there are no oil analysis or service issues): 1. An entire bank of cooling fins appear clogged/disconnected. How is this possible...

IQuestion converting an ungrounded delta system to a HRG setup, understanding the advantages has to offer: Existing System: 23kV delta / 480V delta (ungrounded) 2000KVA transformer - 3 wire secondary bus - 3 wire 2500A 600V switchboard with GF indicating lights. All motor/xfmr loads. 1...

In my opinion, 430.102(A) Exception No. 1 should allow all voltage class motor circuits, not just above 600V.

Thanks all for the replies. On a side note, can anyone give me a true reason a stand alone VSD needs a disconnect within site? I am talking small (480 - 230VAC < 100hp) VSDs. In an industrial facility, drives may be located outside the electrical room (to minimize the drive to motor feeder...

Industrial location. 3 phase 480V delta source - 25A Fused Disc (in a remote location, capable of being locked out) feeds a 15KVA delta-whye drive isolation xfmr (18FLA) (#10 wire). The secondary of this xfmr immediately feeds a 10hp VSD (within 10 feet), which in turn supplies the 10hp motor...