Today I dragged home a 27 kVA 3-phase dry-type transformer. It's old but I'm hoping still serviceable. Inside were 3 very dirty, fragile and waterstained pages stapled together which were the original build document from GS Hevi-Duty back in 1981. The wiring diagram is shown: www.tinyisland.com/images/temp/GSHevi-p3.pdf
It looks like this unit could be rewired for wye or delta for several voltages. I have a 230V RPC set up and running. Can someone give me a recommendation as to how exactly to wire this transformer? I want to power a 460V machine with it.
Use the "secondary" as the primary, connected to the phase converter (X2 joined to X3; X4 joined to X5; X6 joined to X1 per the picture)
Use the "primary" as the secondary connected to the load on the 468V setting (or the 456V setting if measuring the output shows the first to be a little too high) this would be:- tap 4 on the first winding connected to tap 2 on the second winding; tap 4 on the second winding connected to tap 2 on the third winding; tap 4 on the third winding connected to tap 2 on the first winding.
So both sets would be wired delta, but would give you the voltage that you require. You may want to ground the output by using either three wye connected chokes, or three 270V stacks of light bulbs, just to stop the output wandering too far away from ground.
Mark Rand RTFM
If a ground reference on the output is desired, just ground one corner of the delta. Corner grounded delta systems were once common in industrial practice in the US.
Sounds like the proper wiring, but I'd offer a caution. That transformer is a dry type, 26 years old, and the instructions on the inside were wet at some time.
I'd do some testing before hooking the thing up. Look for leakage line to cores, case, ( ground), at a minimum. If you don't have a megger, use line voltage. - (Careful, the secondary will be energized.) MadDog
Looks like a cool transformer and capable! And the document - looks great to me!
Martin H. Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net TSRA, Life; NRA LOH & Endowment Member, Golden Eagle, Patriot"s Medal. NRA Second Amendment Task Force Charter Founder IHMSA and NRA Metallic Silhouette maker & member. http://lufkinced.com /
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