Power Management Corporation

Harold E Hancock

An arc suppression device (40) for protecting the load carrying contacts (30, 31, 32) of a power contactor (20) includes gate controlled semiconductor devices (TR1, TR2, TR3) connected in parallel with the contacts. A signal from a control circuit (45) causes gating current to be applied to the semiconductor devices nearly simultaneously with the application of current to and removal of current from the solenoid (25) of the power contactor. Circuit means (90) responds to the control signals to provide gating current for a limited period of time prior to, during and following the closing of the contacts. Gating current is not continued after the contacts have closed to protect the semiconductors from possible damage. Additional circuit means (110) responds to the removal of the control signal to provide gating current for a limited period of time prior to, during and following the opening of the contacts. An isolation relay (120) may be provided to prevent leakage current from flowing through the semiconductor devices to the load while the power contacts are open.

Solid state arc suppression device

An arc suppression device for protecting the load carrying contacts (25) of a power contactor (15) includes semiconductor devices (TR1, SCR1,SCR2) connectable in parallel with such contacts through an isolation relay (37,61). Gating current to the semiconductor device is applied after the isolation relay is energized and prior to, during and after the power contacts either close or open; but gating current is not continued after the power contacts have closed to protect the semiconductor against damage. Current to the semiconductor is applied before current is applied to or removed from the coil or solenoid (20) of the power contactor. In one embodiment, relays (39,41,43) within the arc suppression circuit (30) control the isolation relay (37), gating current to the semiconductor (TR1) and the coil of the power contactor in the proper sequence. In another embodiment, time delay means (C4-C7,R1) associated with the relays (61,63,65,67) control their sequence of operation.

Growing community of inventors

Cincinnati, OH, United States of America

Harold E Hancock