Pressure and temperature effects on the paschen curve

Abstract

In aircraft applications according to the nature of electrical equipment, its location may be in unpressurized area; thus the environment conditions may change from atmospheric pressure to less than 100 mbar, and the temperature may vary up to 180°C near the aircraft engine. Since all these parameters may affect the discharge ignition voltage, the classical paschen curve has to be replotted according to these parameters. In this paper we firstly investigated the domain of validity of two corrective expressions on the paschen's law found in the literature, in case of changing the air environment: Peek and Dunbar corrections. After that, the effect of the low pressure combined to high temperature on the breakdown voltage at the left of the Paschen minimum has been investigated. Results show two different behaviours of Paschen curve related to temperature and pressure that can be explained by the variation of the breakdown mechanisms, and supported by measuring the energy dissipated in the electric discharge by means of the Lissajous figures at different conditions. Consequently, it was demonstrated that the electrical breakdown in gases occurs due to the gas or vacuum mechanism managed by the temperature and/or the pressure.