Allen-bradley Company, LLC

Lawrence A Burton

David T Rollay

Donald V Zunft

Dennis J Trendel

Marquis B Robinson

Peter Heuser

Walter J Lukitsch

A motor heating control for retrofit applications has an enclosure with power supply terminals and motor heating output terminals. Inside an upper compartment is a first two-pole isolating switch which couples power from the supply terminals through a step-down transformer and a rectifier to one side of a motor heating contactor in the lower compartment. The other side of the motor heater contactor is coupled through fuses and a second two-pole isolating switch in the lower compartment to the motor heating output terminals. An operating handle outside the lower compartment is mechanically interlocked to both isolating switches so that the door of the enclosure cannot be opened without disconnecting both the motor heating power source and the electrical motor from the motor heating control. The motor heating contactor is also electromechanically interlocked to the door interlock mechanism so that the operating handle cannot be moved to its open position until the motor heating contacts are opened. When the motor heating contacts are closed, current will be supplied to at least one motor winding to maintain a temperature of 5.degree.-10.degree. F. above the ambient and prevent condensation in the windings of a motor.

Motor heating control with interlocked dual isolating switches

A contactor includes an actuator which is slidably mounted to a base and carries a set of movable contacts into engagement with a set of stationary contacts when an associated electromagnet is energized. The stationary contacts are located above the electromagnet and are connected to a set of contactor input terminals and a first set of contactor output terminals which extend through the top of the contact enclosure. A second set of contactor output terminals are mounted to the base below the electromagnet where they are easily connected to overload relays. A set of bus bars are mounted to the base and connect the first and second set of contactor output terminals.

Terminal structure for electromagnetic contactor

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Oconomowoc, WI, United States of America

Lawrence A Burton