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We have two plants. One has three banks of tranformers that are corner grounded delta. The other plant has two banks of Y secondaries. Both plants exibit this unbalance. When I mention to the electric company about checking their incoming lines to their sub it gets real quite. We use a REA...

We have two pipe welding mills that use 95% 480 3 phase equiptment.. At both of these facilities when we read the current on a 3 phase motor it is way unbalanced. For instance a 20 HP motor reads 15 19 22 amps. One mill is corner ground delta secondary and the other mill is Y. 7200/480. Our...

I have three banks of transformers in the mill. I get unbalanced current on every 3 phase motor on these banks. The primary 7200 is a Y. The 3 primarys are tied together but not grounded. I only have three lighting transformers in the mill. 2 100 kva and 1 60 kva 480 to 110. None of these are...

What does it mean when connecting 3 phase transformers, additive or subtractive. The local power co. put in a temp transformer to try to correct my unbalanced current but it didn't help. I told them they need to look at the incoming power that was feeding the transformer.

Are both plants fed from the same primary circuit? YES Are you a long way from the substation? 3/4 MILE Are there any voltage regulators between the substation and your plants? Not between that I know of but at the sub. The utility people say they have regulators for each transformer that they...

Someone wrote "Isn't the concern with the voltage unbalance misplaced? It is only 2%, but the current unbalance is very high at 120, 90, 90 (20% unbalance). This much unbalanced current could cause the observed unbalanced voltage. It seems that the problem is with the load, not the source."...

I have had the utility company out to check. They are stumped ?

Each of the 7200 lines feeds an individual transformer and the other tap is tied to all three. Not sure if the center is tied to ground or not. It is a Y connection

WAROSS please look at my post on "corner grounded delta" I have a big current unbalance in my motors from this circuit.

7200 primarys are Y and secondary is corner ground delta

My voltage readings are 471 474 454 Phase to phase Phase to ground is 470 453 4 Current on motor is 135 104 and 90 This is an average volts of 466 So 23 volts would be 5 %. Max difference is 8 volts. Or 2%. All of my motors reguardless of size show this inbalance. If the power company had a...

It is a 480 volt system. Voltages phase to phase range as much as 15 volts.

We ahve three banks of these and muy motor current are far from ballanced I have a grounded delta transformer system. 3 transformers, 3 phase 480 volts. My question is shouldn't my current readings for my motors be balanced? I have a 200 HP AC motor driving a lightly loaded generator. The...