Power Factor Testing in Transformer Condition Assessment -Is There a Better Way?

Abstract

Condition assessment of transformer core-coil assembly, at the factory or in the field, includes one fundamental test: insulation power factor (also known as dissipation factor or tan delta). Although this test can be performed with decades old technology, users have voiced their need for safer, faster, and more portable test devices. This need calls for a review of what makes older test equipment operate at higher voltages and currents. The geometric and material properties examined when performing such tests is discussed. Why the need for higher test voltages when measuring insulation power factor: is it interference mitigation or true material condition assessment? Modern high-power electronics and microprocessor controllers offer alternative methods for packaging test instruments while maintaining accuracy, and improving safety, speed and convenience