Gas Temperature in a Local Discharge on an Electrolytic Solution Surface in Low-Pressure Air under an Impulse Voltage

The relative intensities of the emission spectra from a local discharge on an electrolytic solution surface, which simulates the surface of wet polluted insulators, set in the chamber were measured. The air pressure in the chamber was changed in the range of 53-101kPa to simulate the environment of wet polluted insulators of overhead lines in mountains. The resistivity of electrolytic solution was changed from about 80 to 700Ω• cm. At first, 50% flashover voltage of the solutlon surface was measured. Subsequently, the gas temperature in the local discharge under an impulse voltage of positive polarity was estimated from the comparison of the experimental values with calculated values of the relative intensities of the emission spectra. As a result, it was found that the flashover voltage is in direct proportion to the 0.13-0.34 power of the air pressure and as the resistivity of electrolytic solution drops the influence of the air pressure on the flashover voltage are reduced, and the gas temperature in the local discharge rises with a reduction of the air pressure, regardless of the resistivity of electrolytic solution.