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Short-circuit impedance tolerance of Power Transformers
- Thread starter Joao
- Start date
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
Probably not without spending an inordinate amount of moneyMy question:
As per IEC 60076-1 is allowed uk% tolerances (positives and negatives).
For short circuit issues is possible to request to manufacturers that NEGATIVE TOLERANCES are not allowed? Or even BOTH TOLERANCES?
Tolerances exist partly because %Z is theoretical until after the transformer is manufactured and actual measurements can be performed.
D. Castor
Senior Member
- Location
- Port Angeles, Wash
- Occupation
- Electrical Engineer
You can specify a minimum impedance without too much additional cost, but there will still have to be an acceptable tolerance above the specified minimum.
Yes, we have raised this issue with one Vendor and feedback was that tolerance could be decreased like for example +-5% instead +- 7,5%You can specify a minimum impedance without too much additional cost, but there will still have to be an acceptable tolerance above the specified minimum.
D. Castor
Senior Member
- Location
- Port Angeles, Wash
- Occupation
- Electrical Engineer
Reducing the tolerance range will certainly increase your transformer cost. Why do you feel you need to do this?
Because we are facing issues with Short circuit current levels in 33 kV Switchgears. We want to keep below 31,5 kA. In this project unfortunelly we have start the project from the ROOF.Reducing the tolerance range will certainly increase your transformer cost. Why do you feel you need to do this?