On-site testing of turns ratio is an important basic measurement for power transformer diagnosis. It helps to detect faulty transformer windings as well as defective tap changer positi***.
The simple ratio of turns or voltage and the related ratio error is not sufficient to detect all possible failures of a power transformer winding. The excitation current and the phase angle between primary and secondary windings give additional information about the winding condition.
The simple ratio of turns or voltage and the related ratio error is not sufficient to detect all possible failures of a power transformer winding. The excitation current and the phase angle between primary and secondary windings give additional information about the winding condition.