Transformer Turns Ratio Testing: Finding Tap-Changer Problems
A turns ratio test is only as good as the tap position it is compared against. The pattern of deviations across the tap range separates a real changer fault from a measurement error.
Transformer Electrical Testing
Transformer Electrical Testing: A Practical Guide
A practical guide to transformer electrical testing: turns ratio and vector group, winding resistance, SFRA, excitation current, insulation resistance, and insulation power factor — plus when to apply each test.