Current Transformer Insulation Resistance Test

Modern test equipment for this purposes utilizes a kelvin bridge to achieve results.

Current transformer insulation resistance test.

You might think of a winding resistance test set as a very large low resistance ohmmeter. The insulation resistance test consists in measuring the insulation resistance of a. Transformer winding resistance measurements are obtained by passing a known dc current through the winding under test and measuring the voltage drop across each terminal. Developed early in the 20th century the insulation resistance ir test is the oldest and most widely used test for assessing the quality of insulation.

An approximation is developed to calculate the temperature of winding at that condition. Turns ratio test 8. Historically many field electricians use the somewhat arbitrary standard of 1 megohm per kv. To ensure that each winding of the current transformer has sufficient insulation resistance with respect to earth ct body and between the two secondary cores.

The megger test or insulation test is carried out to ensure the healthiness of the overall insulation system of an electrical power transformer. Ttr transformer turns ratio 5. Current transformer loop test. Leakage reactance 3 phase equivalent and per phase 6.

Generally transformer windings are immersed in insulation liquid and covered with paper insulation hence it is impossible to measure the actual winding temperature in a de energizing transformer at the time of transformer winding resistance measurement. Exciting current test 4. Dc winding resistance diagnostic tests. Insulation resistance is the ratio of the applied voltage dc to the total leakage current.

Ct resistance excitation curve ratio polarity test. The insulation resistance test is the second test required by the electrical safety testing standards. Also acceptable values of insulation resistance depend upon the equipment you re testing. The transformer neutral bushing is to be disconnected from earth during the test.

The transformer resistance testing will reveal a lot of details about the transformer by measuring the winding resistance of a transformer from one hv transformer bushing to another. The international electrical testing association neta specification maintenance testing specifications for electrical power distribution equipment and.