CT winding resistance test is an essential procedure in testing a transformer's performance and ensuring its reliability. This test measures the resistance of the primary and secondary windings of a CT (current transformer) to determine its accuracy.
CT Winding Resistance can be measured either by FLUK or Wheatstone bridge
• Connect the Wheatstone bridge as shown below and measure the CT secondary resistance and compare with nameplate data
• While measuring the winding resistance note down the Ambient temperature to correct the value to factory test results.
After the setup is complete, the test can commence. The resistance value of each winding is measured and recorded by the multimeter. This measurement is usually taken at room temperature, but can also be conducted at a higher or lower temperature if required. In order to obtain accurate results, it is important to ensure that the windings are completely isolated from each other during the test.
Once the resistance values have been recorded, they can then be compared to the CT manufacturer's specifications. This ensures that the CT is operating within its expected range of resistance values, and therefore its accuracy is validated.