Statistical Behavior of Break Arc Durations and the Minimum Arc Sustaining Current

Break arc durations as a function of current from ~0.11.5 A have been examined for Pd, Ag, Pd/Ag, and Au electrodes. Arc durations at !ow currents obey an exponential !aw which changes with increasing current to a log-normal distribution and finally to a relatively random distribution. The minimum arc sustaining current iminis defined as the value of the arc current above which the mode of the arc duration distribution exceeds zero. The results obtained using this definition of iminare in good agreement with the results of other authors. The average arc duration, for palladium arcs in the exponential distribution, correlates well with the volume of the molten bridge formed on break of current carrying contacts.