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Old 08-02-2011, 09:34 PM   #1
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277v-120v transformer problem


I have a 277 volt to 120 transformer that is only pulling 28 volts. Why? Its a single phase 277

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Old 08-02-2011, 09:58 PM   #2
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277v-120v transformer problem


If you have 277 feeding it and 28 coming out, I'd think the TX is bad.

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Old 08-02-2011, 10:41 PM   #3
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277v-120v transformer problem


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Originally Posted by robj116 View Post
I have a 277 volt to 120 transformer that is only pulling 28 volts. Why? Its a single phase 277
Need a little more info to help you out there bud. Could be many reasons why. We all like pictures or at least some more info.
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Old 08-02-2011, 11:31 PM   #4
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277v-120v transformer problem


Possibly you're reading one of the 120V legs to ground and it isn't bonded?

Where is the 28 volts appearing? Is there any load on the 120V side? Is it an electronic transformer or core-and-coils?
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Old 08-02-2011, 11:45 PM   #5
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277v-120v transformer problem


does the transformer need a ground. all we are using is the power lead to the primary side. I get 278v but when I meter the secondary side the best I can get is 28 volts.
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Old 08-03-2011, 12:00 AM   #6
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277v-120v transformer problem


the 28 volts is appearing on the opposite pole from the 277 lead. There is no load on the secondary side.
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Old 08-03-2011, 12:02 AM   #7
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277v-120v transformer problem


It is also a coil transformer
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Old 08-03-2011, 01:08 AM   #8
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277v-120v transformer problem


What wattage the transfomer is and I am pretty sure you have a shorted coil or somecase semiopen coil which the result that you are reading low voltage on secondary side.

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Old 08-03-2011, 02:48 AM   #9
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277v-120v transformer problem


Exactly what two points are you reading 28V between? Is that from ground to one of the secondary leads? If so, the problem is that the secondary is floating and not bonded to ground. Measure between the two secondary leads. You have to ground one of them.
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Old 08-03-2011, 10:03 AM   #10
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277v-120v transformer problem


If you have two primary leads on the transformer and two secondary leads on the transformer, you do not need any grounding to see the output voltage. If you want additional feedback I think you need to give us a better description of the setup. What is the potential use of this transform? How big is it? How about a picture

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