DC Conductivity Measurements of Liquid Silicone Rubber: Influence Analysis and Repeatability

The application of elastomeric insulating materials in high voltage (HV) components has significantly increased and is contributed by their valuable electrical and mechanical properties. Knowledge on DC conductivity of these materials is rare but required prior implementation for high voltage direct current (HVDC) insulation purpose. With the objective of fostering knowledge on DC conductivity of liquid silicone rubber (LSR), measurements are performed using plaque samples. Current-time behaviour is measured whilst a field strength of 10 kV/mm and a temperature of 45 °C is applied. Obtained results provide the base for statistically covered conclusions on the determination of DC conductivity of LSR. Influences of voltage polarities are analysed and dependencies on the measured conductivity, related to previously applied voltage stresses, as known from XLPE, are discussed. It is concluded that for the investigated LSR no significant influences on the measured conductivity due to short circuit duration, polarity, orientation or previously applied voltage stresses are found. In addition to this, statistical indicators regarding the repeatability of measurements are presented.