Non-intrusive Measurement of Transient Electric Field Distribution in HVAC GIL

Measuring the electric field distribution will provide exact information for the design and the safe operation of electrical devices. A simple but effective technique is developed in this paper to measure the transient electric field distribution by fabricating a micro-sized sensor on the grounded (GND) electrode. Both the parameter selection and the fabrication technique are critical for ensuring the non-intrusive measurement. By experiment, the measured electric fields in time domain have exactly the same waveforms as those of the applied AC and impulse voltages, and their spatial distributions are in good agreement with the theoretical calculation results, which proves the correctness and effectiveness of the measurement system. In the future application, the measurement electrodes of the sensor can be designed to be in smaller size and in array form for a more precise measurement. This technique has the potential to be applied in the electric power system for the dynamic monitoring and the defect location of electrical devices.

I. Introduction

Measuring the electric field distribution is critical for the structure design and the condition monitoring of various electrical devices [1] –[5]. Nowadays the numerical computation technique of electric field has been widely used in many engineering fields, but it requires very precise parameters of involved materials, which is actually not an easy work when the complex interactions of the electromagnetic, flow and heat transfer processes are considered. Moreover, when an electrical device is in operation, parameters of materials will change with time, so does the electric field distribution. Therefore, the direct measurement of electric field is highly desired to enable a reliable measuring of the electric field distribution of an operating device [6] –[8].