Transformer Polarity 132V for a 60:1?

[willy47]

A lineman here at work, wants to know why he measures 132V between H2 and X1, when he applys 120V between H1 and H2 with H1 and X2 jumpered? This is an additive distribution transformer. 7200/14400 120/240 I believe.

He is conducting a polarity test and says the transformer has a 60:1 ratio. He gets 132V. My calculations say he should measure 122V. If it was a 10:1, then 132V would be correct.

Thoughts? Thanks for the help.

Dave

 

[GTstartup]

I agree. Why don't you just do a simple ratio check first?

 

[waross]

Are you sure the transformer is not 7200/12470 volts primary?
That would make the ratio 30:1
That would give 4 volts on the 240 volt winding and 2 volts X1 to X2. 120V+2V=122V. I agree with you also.
I wonder if he has found an old 2400 volt transformer in the back lot and tested it without checking the nameplate voltage.
Gee 2400/240 = 10. 10:1

Bill
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"Why not the best?"
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