Current Transformer Insulation Resistance Test

Value at 60 seconds after application of the test voltage is referred to as the insulation resistance of the transformer at the test temperature.

Current transformer insulation resistance test.

Ct resistance excitation curve ratio polarity test. Current transformer loop test. You might think of a winding resistance test set as a very large low resistance ohmmeter. 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.

Ttr transformer turns ratio 5. Dc winding resistance diagnostic tests. September 5 7 2018 ieee c57 152 2013 ieee guide for diagnostic. The insulation resistance test consists in measuring the insulation resistance of a.

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. 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. Apply the test voltage and note the reading. Also acceptable values of insulation resistance depend upon the equipment you re testing.

Insulation resistance is the ratio of the applied voltage dc to the total leakage current. Historically many field electricians use the somewhat arbitrary standard of 1 megohm per kv. An approximation is developed to calculate the temperature of winding at that condition. The international electrical testing association neta specification maintenance testing specifications for electrical power distribution equipment and.

The insulation resistance test is the second test required by the electrical safety testing standards. 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 megger test or insulation test is carried out to ensure the healthiness of the overall insulation system of an electrical power transformer. Modern test equipment for this purposes utilizes a kelvin bridge to achieve results.

Exciting current test 4. Turns ratio test 8.