Interrupting capacity of vacuum interrupters depending on the frequency of current

Results of arc reignition voltages during current interruption of frequencies from 5.9 to 60 kHz by a short vacuum gap are presented. Measured arc reignition voltages depend on current amplitude and frequency, the values of preliminary arc current at the moment of switching on the HF current, and the discharge mode in the preceding current semiwave. Threshold amplitudes of the first semiwave of currents l_m1l and I_m1h as a function of frequency are determined. I_m1l and I_m1h divide current into three ranges to which different kinds of arc reignition voltage distribution correspond. Particularly large dispersion of reignition voltages takes place in the current range from I_m1l to I_m1h. The threshold current I_m1h is inversely proportional to frequency in the range from about 10 to 60 kHz, which is in agreement with the elaborated mathematical model