Measuring procedure of current transformer(CT)

The transportable Omicron CT-Analyzer performs excitation, ratio, and polarity checks on current transformers with the usage of the voltage-comparison method. Current transformers can be tested in their equipment configuration, such as being established in transformers, oil circuit breakers, or switchgear. It is indispensable for the tools to be completely isolated from the electrical gadget before testing.
Polarity Test
Connected to the high voltage winding, the technique used will be carried out by switching on a DC current supply briefly. The polarity can be checked on a polarized voltmeter, linked to secondary winding (low voltage side). The voltmeter has to be calibrated to be positive that the deflection is correct.
Usually, a collection resistor is utilized in the circuit to defend the instrument. If the polarity of the transformer is correct, the deflection have to be in the equal course when the DC current is switched on.
Saturation Test
Measuring the excitation voltage and excitation current that effects as the voltage utilized to the CT underneath test increased. As the CT underneath the test starts to saturate, a giant made bigger in the present day will be detected for a small expansion in voltage. With this test, the magnetization curve and magnetization traits will be confirmed. A saturation check shall be performed earlier than the ratio take a look at and after the polarity test, seeing that residual magnetism is left in the core due to the DC test (polarity, resistance), which leads to extra error in the ratio test.
Ratio Test
The ratio check is carried out by evaluating a voltage utilized by the secondary winding to the ensuing voltage produced on the important winding. For example, if 1 volt per flip is utilized to the secondary winding, the voltage existing on the important winding would be 1 volt. More specifically, if 120V has been utilized to the secondary of a 600/5 current transformer (120:1 ratio), 1V needs to be current on the
primary winding