Background Noise Level in High Voltage Laboratory Measured by using Partial Discharge Current Sensors

Background noise (BGN) measurement is intended to determine the amount of noise which appears naturally in the observed system. This paper discusses background noise (BGN) level in high voltage laboratory measured by using partial discharge current sensors: detecting impedance and high frequency current transformer. The measurement was conducted using these sensors simultaneously in five days during working days from 09.00 to 16.00. The pico-coulomb (pC) calibrator was used to convert the noise level in milivolts (mV) into related amount of electric charges in pico-coulombs (pC) as a unit charge. The measurement results show that the lowest noise level measured using RC sensor (0.4 mVor 0.46 pC) was obtained on Thursday at 09.00. The highest noise level measured using RC sensor (2.56 mV or 2.91 pC) was obtained on Tuesday at 11:00. The lowest noise level measured using HFCT sensor (2.4 mV or 1.52 pC) was obtained on Friday at 15:00 the highest noise level measured using HFCT sensor (11.56 mV or 8.10 pC) occurred on Thursday at 10:00. The HFCT is more sensitive in measuring the background noise than the detecting impedance.