how to perform winding resistance test on transformer

[mask12900]

please describe step by step guide how to perform winding resistance test on three phase dry type transformer

[bmclean]

please describe step by step guide how to perform winding resistance test on three phase dry type transformer

Using a Transformer Winding Resistance tester connect the current leads and Voltage leads across a winding(In a Wye connected transformer it will be A-N,B-N,C-N, for Delta it will be A-B,B-C,C-A) wait for unit to stabilise and record value.

Delta values should always be measured values x1.732.

[wooddy]

Using a Transformer Winding Resistance tester connect the current leads and Voltage leads across a winding(In a Wye connected transformer it will be A-N,B-N,C-N, for Delta it will be A-B,B-C,C-A) wait for unit to stabilise and record value.

Delta values should always be measured values x1.732. i usually do test at 10% of rated current and make sure winding temperature is measured so readings can be corrected to manufacters readings

[jflan13]

To tag on to the 10%, I have always heard you shouldn't exceed 10% rated current. Also the Manual for the Vanguard TTR and Winding resistance sets have really good info for dry types with in accessible neutrals and other nonstandard configurations.

http://www.vanguard-instruments.com/download

Breeze through and check out the manuals they have, I learned a good bit from them

[Kalbi_Rob]

To tag on to the 10%, I have always heard you shouldn't exceed 10% rated current. Also the Manual for the Vanguard TTR and Winding resistance sets have really good info for dry types with in accessible neutrals and other nonstandard configurations.

http://www.vanguard-instruments.com/download

Breeze through and check out the manuals they have, I learned a good bit from them

Xmfr manufacturers typically recommend that the current output
selected should not exceed about 10% of the rated winding current, because it will cause erroneous readings due to heating of the winding.
• Always choose the highest current output possible for the expected resistance
value.
• Typical ranges are 0.1-10 % of rated winding current

Here are some slides from RichmondCC:
http://engineering.richmondcc.edu/Courses/EUS%20215/Notes/Transformer%20Winding%20Resistance%20Test.pdf

Here is the procedure from TestGuy.net for Winding Resistance Testing:
https://testguy.net/content/276-Transformer-Winding-Resistance-Testing-Explained