10 lead Generator winding identification, & low voltage readings.

[NJ_Bill]

thread238-314092

I have a 10 lead generator that I have installed in series Y to supply 480 3 ph. Most of the leads where marked (unknown if correctly marked). When I run the gen set, I get 480ish volts (haven't tweaked the regulator yet) on A - B, 360ish volts B - C, and 360ish C - A. Therefor my guess would be A leg is correct,and B leg is correct, and something is off on the C leg, since it is common to both the A - C, and B - C voltage readings. Reading waross's post in the above referenced post, if I had one winding backwards on the C leg, the output on that leg should be 0 volts to neutral. Would this then give me the low voltage I am seeing, or is there something else strange going on?

Thanks, Bill.

 

[waross]

Disconnect the connections.
1. Find the 4 leads that have continuity.
They will be 7, 8, 9, & 10.
# 10 will be the common or neutral.
If you have enough markings to fill in the numbers, fine. Else run the set and find the neutral, or #10.
Use the other numbers if available or number the phase leads arbitrarily.
2. Find three pairs of windings with continuity.
3. Connect one winding to #7 and check the voltage. If the voltage is zero, reverse the winding and try again.
If you get 480 277 Volts from the free end of the winding to the neutral you have identified #1 and #4. #1 is the free end,- #4 is the end connected to #7.
If you don't get 480 277 Volts, disconnect the winding and pick another winding and go to step 3.
4 Once you have identified #1 and #4, pick another winding and connect to #8. Once you get 480 277 Volts, the free end is #2 and the end connected to #8 is #5
5 Last winding. connect and check until you get 480 277 Volts. Once you get 480 277 Volts, the free end is #3 and the end connected to #9 is #6.
Good luck.
PS I hate it when the numbers get lost. My personal worst was a Dahlander motor with all leads disconnected and no numbers.
It was taken out of storage and whoever removed it from the original machine managed to destroy the wire numbers.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[NJ_Bill]

So, 1-4 + 7-10 = 480, 4-1 + 7-10 + 0 volts? If so, with winding 1-4 backwards so it was actually 4-1,what would be the voltage be between 4 to 2, 2 to 3, 3 to 4?

 

[waross]

Please note my corrections above. We are measuring from the neutral so we should be seeing 277 Volts, not 480 Volts.
As a quick guess you may have a winding connected backwards on the wrong phase.
Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[NJ_Bill]

I missed that too, Agreed leg to "neutral" = 277.
Thanks from one Bill, to another Bill.