# 112.5kVA xfmr



## Zog (Apr 15, 2009)

Winding resistance? Insulation resistance? DAR? Turns ratio? 

You do any of these tests?


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## MattJ (May 7, 2014)

Zog said:


> Winding resistance? Insulation resistance? DAR? Turns ratio?
> 
> You do any of these tests?


No, but would that change the fact that there's no voltage from B phase? Just trying to get some seasoned input here, if such tests would benefit me, let me know. The party without power is losing money daily.


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## Big John (May 23, 2010)

Sounds to me like X0 is not in fact grounded, and X2 has a ground fault.

It would explain your high voltage on the remaining phases.


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## micromind (Aug 11, 2007)

Big John said:


> Sounds to me like X0 is not in fact grounded, and X2 has a ground fault.
> 
> It would explain your high voltage on the remaining phases.


I agree. 

Test voltage from X1 to XO, X2 to XO and X# to XO. I bet you get 120 on all 3 tests. If so, then XO is not bonded to ground.


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## ponyboy (Nov 18, 2012)

micromind said:


> I agree. Test voltage from X1 to XO, X2 to XO and X# to XO. I bet you get 120 on all 3 tests. If so, then XO is not bonded to ground.


I must be a little slow. Could you explain this to me?


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## glen1971 (Oct 10, 2012)

MattJ said:


> I just finished troubleshooting a Sorgel 3 phase general purpose transformer from square D. Primary 480v secondary 208y/120v. Transformer x2 has 0 volts to ground. X1, x3 roughly 200v to ground(too high). H1,h2,h3 277 on the money to ground. 480v phase to phase. I shut down power checked terminations, bonding etc. Onsite maintenance says it's about 12 year old unit. It's indoors, temp controlled room. Does this sound normal? Any suggestions? Thanks.


Meter X1 to X3 and you should be around 208 volts.. With X2 to ground reading 0 volts you have a fault on that phase somewhere in the system...Isolate each load until your voltage returns to normal (120 to ground on all 3 and 208 phase to phase).


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## varmit (Apr 19, 2009)

It appears that XO is not bonded to a GEC and there is a ground fault on X2. If XO was properly bonded and there was a ground fault on any phase, a fuse/breaker would trip. If XO is not bonded on a wye system, any phase to ground readings will be meaningless.


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## Big John (May 23, 2010)

ponyboy said:


> ...Could you explain this to me?


 He already knows his L-G voltages, so if he measures his L-L voltages and they are dead-nuts then that means he doesn't have a winding failure, so it just confirms the grounding issue.

If he gets some screwball L-L voltages, then there's something else going on. But he should also do his N-G voltage.


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## MattJ (May 7, 2014)

Big John said:


> He already knows his L-G voltages, so if he measures his L-L voltages and they are dead-nuts then that means he doesn't have a winding failure, so it just confirms the grounding issue.
> 
> If he gets some screwball L-L voltages, then there's something else going on. But he should also do his N-G voltage.



X1 to x3 was coming in around 220v and N to G was 120v.


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## MattJ (May 7, 2014)

XO was bonded to ground inside the panel fed by xfmr. Thanks for all the input by the way, I look forward to figuring this out.


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## 8V71 (Dec 23, 2011)

MattJ said:


> XO was bonded to ground inside the panel fed by xfmr. Thanks for all the input by the way, I look forward to figuring this out.


If X0 is bonded to ground in the panel but you are measuring 120 volts to ground at the transformer, wouldn't that mean you don't have continuity to the panel on either X0 or ground?


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## Big John (May 23, 2010)

8V71 said:


> If X0 is bonded to ground in the panel but you are measuring 120 volts to ground at the transformer, wouldn't that mean you don't have continuity to the panel on either X0 or ground?


 It would, but I don't know that he's taken that measurement. That needs to be his next step.


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## 8V71 (Dec 23, 2011)

Big John said:


> It would, but I don't know that he's taken that measurement. That needs to be his next step.


I should probably just stick to reading. I thought X0 was neutral.


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## Big John (May 23, 2010)

8V71 said:


> I should probably just stick to reading. I thought X0 was neutral.


 The terminology is messed up here. I read that his neutral conductor is bonded in his panel. We're calling it X0, but it's not. I don't think we know what the actual X0 to ground reading is.


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## 8V71 (Dec 23, 2011)

MattJ said:


> X1 to x3 was coming in around 220v and N to G was 120v.





Big John said:


> The terminology is messed up here. I read that his neutral conductor is bonded in his panel. We're calling it X0, but it's not. I don't think we know what the actual X0 to ground reading is.


The top quote is his post previous to the one I quoted. Does this help?


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## Big John (May 23, 2010)

8V71 said:


> The top quote is his post previous to the one I quoted. Does this help?


 Thanks, I missed that reply completely.


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