Threshold Voltage of the Negative DC Surface Corona ?Effects of Various Insulators and Humidity?

摘要

We have studied the influences of insulators and humidity on the threshold voltage of the negative DC surface corona. Acryl resin, Phenol resin (Bakelite) and glass have been used for sample plates for the electrical insulator. Experiments of the surface discharges with and without the backing electrode using the needle-to-blade of the razor gap have been tested in room air and dry air at 760 mmHg pressure. The radius of curvature of the needle was 0.2 mm and gaps were 10 and 20 mm. The corona onset voltage and the corona threshold voltage have been measusured with the various insulators. Electromagnetic oscillograph has been used to measure the corona current and the voltage and photo-currents which has been measured with the photomultiplier tube