Transformer power questions

[steelerfan1984]

Hello, I’m new here and have been scouring the forums for an answer. I recently purchased a wash and I’m doing an update on it.

I’ve updated all the meter boxes and ran new wire to the pump stands, my problem is the voltage coming out of the transformers is like 10v on one leg and like 10 on the neutral. It’s a 120v/220v 100va transformer and I’m pulling a 110 leg off the contactor for the primary side and a common ground, voltage from contactor is 120v. Now these are old parts and this is the first pump/bay I am working on.. sooo..

I suspected it was just the transformer but what I have done is, check the other transformers on other bays and they will put out 24v. I then remove the transformer, put it on the pump im updating and it seems fine at first, then soon after I check my voltages, I double check and it’s got wonky voltages on both legs again. These are simple transformers, old as can be, but 2 wires coming in, 2 going out, I am putting grounds on both a sides.. any ideas as to what could cause these seemingly good transformers to crap out when I swap.. I believe I am hooking up correctly. Primary to 1 leg of the 3 phase and a ground… thanks in advance

 

[DavidM]

It may depend on the type of 3 phase that you have but ours are not wired to 1 leg and ground, they are wired to leg 1 and leg 2.
Do you have 110v on leg 1 and ground?
I'm not an electrician but that doesn't sound right to me. Is that how the other bays are wired?

David

 

[steelerfan1984]

I’m not at the wash so I can’t verify what your asking at the moment, but the funny thing is, I am mimicking how it was wired from power to contactors, transformers etc, and it seemingly worked with the old equipment. I started to suspect something might have to do with my phases, cause one is a high leg, but I am putting the 120 on a normal leg and it checks out on the wire going to the transformer..

The transformer only has a white and a black for the primary side so I’m not sure where I’m going wrong from 120v from contactor to the transformer power

 

[DavidM]

Check the wires feeding one of the other transformers. My guess is they are 220v and the transformer drops it to 24v but when you move it, you are feeding it 110v and getting 10v on the secondary side.
A 110/220 primary by 24v secondary should have 3 or 4 wires not just 2.