Design of a Multi-channel PD Detector for Improving Common-mode Noise Reduction Performance in Measuring and Monitoring System

Abstract

This paper deals with the design and implementation of a multi-channel partial discharge (PD) detector to improve noise reduction performance in the designed PD measuring and monitoring systems. Basically, the noise may be generated by the unexpected ground loop of the PD measuring system due to several coupling devices (CDs) being connected to the PD measuring instrument. In this paper, the signal-to-noise ratio (S/N ratio) was enhanced by using a bandpass filter and a programmable gain amplifier to filter the undesired noises and amplify the PD signal acquired in the CD. Besides, the category 7 cable (CAT7 cable) was utilized as a transmission line to transmit signals into the PD measuring instrument. This CAT7 cable with the grounded shield is comprised of 4 pairs of cables, i.e., the DC power supply cable, the PD signal cable, the test voltage signal cable, and the control signal cable used to connect between the coupling devices and the measuring instrument. Furthermore, at the input side of the measuring instrument, the Differential Receiver Amplifier was utilized to reduce the common-mode noise generated from the coupling device. Application of the proposed technique, the battery power supply, and the sophisticated isolation technique, e.g., fiber optic cable system of the active coupling device, are not needed. Furthermore, the designed PD detector was a simple and cheap price, including significant noise reduction.