Contact wear monitor with comparison system - compares reference wear value with instantaneous wear values determined from load current

摘要

The monitor determines the wear of electrical contacts and indicates when a given wear limit has been reached. Wear is monitored by comparing the actual wear with a reference wear known by previous experiment and representing an unacceptable amount of contact wear. Auxiliary contacts (10, 16) operate at the same time as the contact (1) being monitored and trigger the read out of a memory (7). The memory stores 'wear figures' (previously determined) corresponding to given load currents. The load current is measured inductively (4, 5) and converted into a digital signal (6). The memory 'wear figure' at any moment is passed to an adder (11) where is outputted for comparison (12) with the reference wear (13).