Current transformer (CT) test procedure
- Test objective:
This test is considered as one of the main test, it's aimed to test:
• Current transformer ratio.
• Current transformer polarity.
• Burden of current transformer.
• Knee point of current transformer.
• Current transformer winding resistance.
• Magnetization curve of current transformer.
• Megger test (insulation test).
-Required Equipment:
• Current transformer (CT) analyzer.
• Insulation resistance tester
-Mechanical check and visual inspection:
• Check the tightness of all connections.
• Check ferrules
- Current transformer analyzer connection:
1. CT analyzer has 4 leads, two should be connected to the primary side which contains the primary side of CT and the other two should
be connected to the secondary side of CT which you want to check its ratio.
2. After connecting the CT analyzer through the laptop and using CT analyzer software, the test can be started and results can be printed out for CT ratio, CT polarity, CT burden, CT knee point & CT winding resistance.
3. This result should be compared with the current transformer factory test and be sure that the result within acceptable tolerance.
4. To measure the burden: Inject 1 ampere on the secondary side of the CT, and using a multimeter you can measure voltage calculate burden by multiply voltage and current and comparing it with the CT burden.
5. To test insulation: Using megger by 1 kilo volt injection for 1 minute, this test should be done between primary to secondary and secondary to secondary But for Primary to ground 5 kilo volt injection for 1 minute.
6. See Figure.1 which shows the CT analyzer connection for CT TEST
HYCT-100 CT Analyzer is a new product created after widely adopting customers' advice and deep theoretical study. It is based on the automatic FA Series Transformer Tester General which is produced by our company that is widely acclaimed and applied. The adoption of high-performance DSP and ARM, advanced manufacturing technology ensures stable and reliable product performance, full-featured, high degree of automation, high efficiency, in the domestic leading level, they are the professional testing equipment for transformer check in the power industry.