Electrical contactor with controlled closing characteristics

摘要

A microprocessor controlled electrical contactor 10 monitors the voltage A and peak current B produced by a first voltage pulse P1 gated to the coil 31 of the contactor electromagnet 30 and adjusts the conduction angle beta 2 of the second pulse P2 to deliver a constant amount of electrical energy to the electromagnet coil despite variations in coil resistance and supply voltage so that the contactor contacts 22, 26, 46, 48 can be consistently closed with low impact velocity and minimum contact bounce. Normally, the third P3 and subsequent pulses are gated to the coil at constant conduction angles selected so that the contacts consistently touch and seal on a preselected pulse with declining coil current. Under marginal conditions, determined by the peak current Ipeak produced by the first pulse, the third and subsequent pulses are gated at substantially full conduction angles to assure contact closure. If the voltage or current produced by the first pulse is below a predetermined value, closure is aborted. IMAGE