Abstract: A system for controlling the start-up sequence of an electric motor includes a contactor relay for supplying polyphase operating voltage to the motor. A plurality of output circuits are respectively coupled between the motor and the relay contacts. Each output circuit is responsive to an output control signal applied to an input thereof for applying the operating voltage to the motor. An acceleration ramp generator is responsive to a motor control circuit which energizes the relay for providing a first signal which gradually rises upon the initial activation thereof. A phase control ramp generator is responsive to the application of the polyphase operating voltage to provide a second signal which decreases from a given level upon the initial application of the operating voltage. A plurality of comparators are provided each comparator having first and second inputs respectively coupled to receive each phase control ramp generator signal and the acceleration ramp generator signal.

Abstract: A D.C. solenoid control circuit for use in mechanisms driven by an A.C. motor. A rectifier converts A.C. current to D.C. current and provides an A.C. current flow path and a D.C. current flow path. Only the motor is connected in the A.C. current flow path to an output electrical power source. The D.C. solenoid is connected through the rectifier in the D.C. current flow path. The D.C. solenoid winding drives an actuator within the solenoid the activate the separate mechanism. In-rush current drawn by the motor upon start-up is converted to a high current level by the rectifier and input to the winding of the solenoid causing its immediate energization and, upon de-activation, its fast release.

Abstract: The improved hoist includes a direct current brake and a control therefor. In the brake control, the AC current is rectified with DC current being sent to the brake solenoid. When the hoist is operating, the brake solenoid is energized to hold the brake in the unactivated position. A timer and power reducer are utilized to reduce the power on the solenoid while the hoist is in operation, thus reducing the energy expended while the hoist is in operation. The operating speed of the brake is increased since less power must be dissipated from the solenoid before the brake can be actuated.