The transformers are not 180 kVA unless they were made as a very special item. The standard three phase sizes are 75, 112 1/2, 150, 300, 500, 750, 1000, 1500, and 2000. Yes they grow them larger and smaller than that but that is all I listed.

I agree that the installation is not good looking and that it is not likely that it would be done that way today (this is an old installation). However, the installation looks safe to me even though it would not meet the rules in the current NESC.

The primary voltage is probably 34.5 kV since there are three bells on the dead-end. It is difficult to judge that aspect without seeing the pole tops. The secondary voltage would be 480Y/277 on the right hand transformer because you can see four conductors hitting the bus head.

I would make a guess that these are in the range of 1000 kVA, 34.5 kVA-480Y/277 V transformers. There are problems with ungrounded delta services but there are advantages as well. It is up to the plant engineers to make the decision with the serving electric utility as to whether or not an ungrounded service would be acceptable. The Soares Grounding book from the IAEI has a very good dissertation about ungrounded services. Note that this is an industrial substation and is probably not exposed to the general public and may even be a customer owned substation (would still be built to the rules in the NESC since the NEC defers to the NESC). The suspicion that it is a customer owned substation is based on the ground level switch handle on the left hand pole, an electric utility would not have that type of switch but the NEC requires it. [Linked Image]

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Charlie Eldridge, Indianapolis, Utility Power Guy

Charlie Eldridge, Indianapolis Utility Power Guy