When conducting insulation PF tests, for liquid filled natural ester/ester transformers, why does NETA ATS ask for a max of 1% PF but NETA MTS indicates a max of < 3% PF? (refer to table 100.3 in both standards, assume no manufacturer test results/guidelines are available).
Many natural ester transformers can’t meet the NETA ATS standard, or just barely pass.
If the PF result comes back greater than 1%, but less than 3% would you still accept it during the ATS testing portion or fail it? What do you do if it fails as the equipment owner?
Curious to know anyone’s experience regarding this.
