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# Transformer Winding Resistance

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1. Junior Member
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## Transformer Winding Resistance

Hi everyone, I hope you all doing okay. I wonder something and you are the best crew i can ask
When we test winding resistance test for transformer we saw discrepancy in results when compare with the Factory Test results. Is there any way to calculate the result and see the true values? I research it but i couldnt find a good way.
Thank already...

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## Transformer Winding Resistance

Originally Posted by changeabilities
Hi everyone, I hope you all doing okay. I wonder something and you are the best crew i can ask
When we test winding resistance test for transformer we saw discrepancy in results when compare with the Factory Test results. Is there any way to calculate the result and see the true values? I research it but i couldnt find a good way.
Thank already...
We need more information to help you with your problem.
1. Did you convert your results for temperature conversion from the reference temperature from the factory test report?
2. Did you measure the Delta winding from L1 to L2 ?
3. Did you measure the Wye winding from X1 to X2 or from X1 to X0?

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Originally Posted by cunin21
We need more information to help you with your problem.
1. Did you convert your results for temperature conversion from the reference temperature from the factory test report?
2. Did you measure the Delta winding from L1 to L2 ?
3. Did you measure the Wye winding from X1 to X2 or from X1 to X0?
Thank you for your response.
1- The results are very different so even if i correct according to reference temperature i dont think it affect a lot.
2- I have Vanguard WRM-10p 3 phase so i have results for 3 phase.

The difference between the factory results and my results is more than 20%.

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Originally Posted by changeabilities
Thank you for your response.
1- The results are very different so even if i correct according to reference temperature i dont think it affect a lot.
2- I have Vanguard WRM-10p 3 phase so i have results for 3 phase.

The difference between the factory results and my results is more than 20%.
The Vanguard is a good test set. We use it all the time with very few issues. Most troubles are the test leads. What kind of transformer is this? Is it dry or liquid and does it have a LTC? How about posting your winding resistance results.

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Originally Posted by cunin21
The Vanguard is a good test set. We use it all the time with very few issues. Most troubles are the test leads. What kind of transformer is this? Is it dry or liquid and does it have a LTC? How about posting your winding resistance results.
It is oil filled transformers. It has a LTC. There is no problem on primary windings results but secondary results are very different.

Factory results is like 3 milliohm but my values are around 270 microohm.

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Originally Posted by changeabilities
It is oil filled transformers. It has a LTC. There is no problem on primary windings results but secondary results are very different.

Factory results is like 3 milliohm but my values are around 270 microohm.
Is this a new transformer or are you doing maintenance testing? Are the primary windings all within 1% of one another? On a winding with a tap changer do your testing with the tap off N. Use tap 1R or 1L. We run a winding resistance test from 16R to 16L with the test set on. If the test set kicks out we know that a set of contacts are breaking before making.Your results are very high. Are the phases within equal results?

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Originally Posted by cunin21
Is this a new transformer or are you doing maintenance testing? Are the primary windings all within 1% of one another? On a winding with a tap changer do your testing with the tap off N. Use tap 1R or 1L. We run a winding resistance test from 16R to 16L with the test set on. If the test set kicks out we know that a set of contacts are breaking before making.Your results are very high. Are the phases within equal results?
This is a new transformer and primary windings results all within 1% of one another. i made the test in all taps actually. Secondary results are same for sure in all taps. What should be the results for 2500 kVa 15000/400-230 v transformer? Maybe there is a mistake on factory reports.

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Originally Posted by changeabilities
This is a new transformer and primary windings results all within 1% of one another. i made the test in all taps actually. Secondary results are same for sure in all taps. What should be the results for 2500 kVa 15000/400-230 v transformer? Maybe there is a mistake on factory reports.
Some factory results are measured x1 to X2, X2 to X3, X3 to X1. Your test may include bus bars that there test did not include. I would say the results should be around 230 Microhms.

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Originally Posted by changeabilities
Hi everyone, I hope you all doing okay. I wonder something and you are the best crew i can ask
When we test winding resistance test for transformer we saw discrepancy in results when compare with the Factory Test results. Is there any way to calculate the result and see the true values? I research it but i couldnt find a good way.
Thank already...
Are you asking for temperature corrected value or to try and calculate the values based off the voltage and current of the transformer?

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Originally Posted by rmr660
Are you asking for temperature corrected value or to try and calculate the values based off the voltage and current of the transformer?
Hi
I want to try and calculate the values based off the voltage, current and power if its possible.

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