论文信息 - Effect of short circuit current duration on the welding of closed contacts in vacuum

Effect of short circuit current duration on the welding of closed contacts in vacuum

High ac currents were passed through closed Cu-Cr (25 wt. %) contacts located in a vacuum ambient (pressure 10/sup -4/-10/sup -3/ Pa). The duration of the short circuit currents ranged from 1 second to 4 seconds. The contact welding was measured for a range of closed contact forces and current durations. The weld fracture strength was measured using a slowly rising opening force of 50 N/s. It was found that the contacts required a larger contact force to prevent welding if the current duration of 4 seconds was applied, than if a current of 1 second, 2 seconds and 3 seconds was applied. The data showed that there was a considerable scatter in the data for all conditions examined. It also showed that a weak weld could well follow a strong weld. A consideration of the transition to the steady state model of closed contact welding can explain the observed data.

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