Scheduled tests are essential in detecting effects that can occur within the life cycle of a transformer such as shorted coils, loss of class accuracy due to material changes, or changes to the load.
Turns Ratio Test is used to make sure that the Turns Ratio between the windings of the transformer is correct. This ratio decides what the output voltage of the transformer will be with respect to the input voltage. The ratio is calculated under no-load conditions, with ratios calculated at the tap positions for each winding and for the winding as a whole.
Insulation Resistance Test – The Winding Insulation Resistance test, also known as the Megger test is a measure of quality of insulation within the transformer. It can vary due to moisture content, cleanliness and the temperature of the insulation parts. All measurements are corrected to 20’C for comparison purposes.
The simplest of all, performing routine visual tests can reveal potential problems.