Development of Standard Measurement Device for 0.1Hz VLF Dielectric Loss Tester

Dielectric loss is an important characterization of insulation performance of power cable. Measuring the dielectric loss of a power cable can effectively evaluate the cable status. There are a large number of power cables, and the operating life is gradually increasing in China's power grids. To prevent accidents and improve the reliability of grid operation, power cable dielectric loss testers are commonly used in 10kV and 35kV power level, but there is still a lack of standard measuring devices to test their performance. For this reason, in this paper, a standard measuring device is proposed, the working principle of the device, the selection method of key components is introduced, and the actual dielectric loss tester using this device is tested. The research results show that the developed device is fit for the calibration of the power cable dielectric loss tester. When the dielectric loss value is high, the difference between the theoretical standard value and the actual measured value is small. However, with the decrease of the dielectric loss of the standard sample, the difference between the theoretical standard value and the actual measured value gradually increases. The reason for this phenomenon is that the capacitor used in the standard test device also has a resistance. The method of recalculating the theoretical standard value considering the resistance value of the capacitor can reduce the difference between the theoretical standard value and the actual measured value, so as to carry out the calibration better.