480/240 Delta / Delta Transformer X4 question

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mmiller

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I have a transformer 3 phase 480v primary to 240v secondary. Its 15kva and is supplying a unit that controls and powers heaters for an injection mold system.

This particular transformer has an X4 tap to give 120v for control voltage etc...

I don not need this voltage at all do I need to do anything with the x4 tap ?

Thanks
Mike

I'm curious because this system has been working fine in the past and the operators plugged it in today and I was getting 65 volts out of the secondary. I checked my supply voltage and all leg to leg readings are at 480v at the connection. Once hooked onto the H1-H2-H3 I have 365v from H2-H3..... all connections are solid and tight could the transformer be bad ???
 
As far as X4, there are two schools of thought. Some folks would ignore it. Others, relying on 250.20(B) would say you were required to ground it.
If you choose to operate it as an ungrounded system, under recent Codes 250.21(B) would require ground detectors.

I'm afraid I don't understand the second part of your post.
Is there a typo ? If you have 480 on the primary (H1-H2-H3) how are you measuring the 365 v ?
 
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