A Beginner's Guide to testing procedure of current transformer

Current transformers (CT) are one of the most important components in power systems as they provide a means of measuring electric current. To ensure that the CTs function as expected, they need to undergo testing procedures that help establish their accuracy, reliability, and safety. In this article, we explore the testing procedures involved in testing the current transformers.

Enter the rating plate data in test sheet and compare the current transformer data with the data contained in the circuit documentation. The following test shall be carried out.

1. CT Winding insulation Resistance test

2. CT Ratio test by primary injection

a. CT Ratio

b. Phase Angle Error

3. CT Winding Resistance Measurement

4. CT Loop Resistance Measurement

5. CT Polarity Test

6. CT Burden test

7. CT Magnetizing Current Test (Knee Voltage test)

8. Demagnetizing CT cores after above all the test

9. Inter Core coupling Test for bus differential test

10. High voltage test

11. Verifying secondary circuits, terminals, shorting/isolating links by primary

injection

12. single point earthing check

13. phase identification

It is essential to perform these tests regularly, especially after maintenance, repair, or installation of CTs. Testing ensures that the CTs are correctly installed, connected, and calibrated, thereby improving the safety and efficiency of power systems. Wuhan Huayi electric power technology develop and make the CT analyzer, which has different models and functions, that can meet your test requirements. The function is powerful, the performance is stable, and test result is accuracy.