Hvdc switching using microprocessor for polarization and depolarization measurement

Abstract

Polarization and Depolarization Current (PDC) testing is a non-destructive dielectric testing method to determine the conductivity and moisture content of the insulator. This paper presents the application of microprocessor in HVDC (High Voltage Direct Current) switch to switch “ON” and “OFF” the PDC measurement circuit. This paper also reviewed the involvement and also the function of microprocessor to control the switching circuit and also the function of auxiliary circuit in controlling the voltage balancing of each device in the IGBT (Insulated Gate Bipolar Transistor) circuit. A simple and reliable technique of voltage-balancing circuit for the series operation of devices is presented to overcome the unbalance load and it is well controlled by the microprocessor circuit. The operation principle and analysis are presented and tested on 2 series-connected of 600-V/5-A insulated gate bipolar transistors to handle 1-kV/400-A switching for 10,000 seconds.