Table Mounted Lightweight Rectangular Power Transformer Tester

A dielectric loss testing program provides several important benefits. Periodic tests performed during the service life of the equipment can indicate that the insulation is either aging normally or deteriorating rapidly. Diagnostic tests may disclose the location of a fault or the reason for failure. Insulation Resistance and Polarization Index is the most widely practiced and accepted test in identifying the dryness/wetness of paper insulation. The life of the transformer is mainly based on or is very sensitive to the amount of moisture content in paper insulation. This test gives information on the aging condition or status of the insulation, and moisture content in paper and hence is a very important test for identifying residual life.

Dielectric Loss Measurement (DLM) in an insulation system is the power dissipated by the insulation when subjected to an applied alternating voltage. A high loss may indicate problems in the insulation structure. Normal aging of insulating material will cause dielectric loss to increase. Contamination of insulation by moisture or chemical substances may cause losses to be higher than normal. Physical damage from electrical stress or other outside forces also affects the level of losses.