Pressure Waves Due to Arcing Faults in a Substation

The collapse of the building housing a large substation following an arcing fault motivated the measurements of the amplitude of the pressure wave generated by an AC arc with current from 10 A to 80 kA and with arc length from 8 mm to 15 m, burning in air for up to one second. At low arc power there is a correspondance between the pressure amplitude and the rate of change of the power which is not true for high arc power due to absorption. However, the pressure is very large and should be taken into account in the design of substations. An empirical formula is given relating the pressure variation amplitude to the short-circuit current and the response time of the protection system.