Reignition Voltage of Arcs on Double-Break contacts

Experimental studies were made of the arc reignition voltage on double-break contacts for fine silver (Ag 1000), AgNi 90/10, AgCdO 90/10, and AgSnO288/12. The experiments were carried out in an ac circuit with air-core reactors (power factor 0.4). The frequency of the transient recovery voltage oscillation ranged from 10 (or 5) to about 70 kHz. The reignition voltage after an arc having a duration of close to onehalf cycle (-~10 ms) was measured 15-25 times in a fixed-circuit condition. In the high-frequency range of the voltage oscillation, the value of the average reignition voltage does not depend upon the frequency, and at 103 A this constant value (immediate recovery voltage) is smaller than that at 57 A. The ratio of the reignition voltage () of the double break to that () of the single break at the same reignition time (time after current zero) has the value of 1.7-1.8 for AgNi 90/10, AgCdO 90/10, and AgSnO288/12. Onlyfor Ag is the ratio (/) found, interestingly, to be almost two. This fact is considered to be due to the glow discharge which precedes the arc establishment.