Abstract: A circuit and method measures main motor winding voltage and detects points in the electromagnetic wave cycle where this voltage “crosses” zero. It also measures auxiliary motor winding voltage. Phase shifts measured in the auxiliary winding are compared as a means for starting and restarting the auxiliary winding. The points in the electromagnetic wave cycle where the current in the auxiliary winding “crosses” zero are detected and compared with a first window pulse that is generated when the main voltage crosses zero. When the zero current crossing points fall outside the first window pulse, the auxiliary winding is disconnected. The points where the voltage in the auxiliary winding “crosses” zero are also detected and compared with a second window pulse that is generated when the main voltage crosses zero. When the zero voltage crossing points fall within the second window pulse, the auxiliary winding is switched back into the circuit.

Abstract: An automatic reverse system for a shredder machine automatically causes reversal of the shredder motor when the system becomes jammed. A centrifugal switch connected with a starter winding of the drive motor disconnects power feed thereto when the motor is rotating above a predetermined speed. A manually actuated switching circuit in combination with the centrifugal switch initially energizes the system for forward operation. When a jam occurs, the centrifugal switch together with the switching circuit automatically causes a reversal in the direction of rotation of the motor, the reverse operation continuing until the operator manually actuates a switch to deenergize the system or when an automatic switch halts reverse rotation after a predetermined time period.

Abstract: A circuit for use with an induction generator. The circuit is arranged to initiate operation of the induction generator as a motor to bring the system up to operating speed and subsequently to rearrange the system automatically to cause the induction generator to operate in a generating mode. The automatic reconnection is effected as an incident of the motor reaching a preselected speed. Determination of the preselected speed may be effected by voltage responsive means in one form of the invention, and by centrifugal switch in another form of the invention. The control is effected by suitably selectively connecting the phase winding of the generator. In the illustrated embodiment, a starting capacitor and a power factor correction capacitor are automatically connected at proper times in the operation.

Abstract: A reciprocating drive system moves a body of defined inertia, such as a carriage supporting electrostatic spraying means, at full speed between two points at which the direction of movement is reversed. The drive system includes an electric motor with polyphase stator windings and a squirrel cage rotor. Transducers responsive to the arrival of the moving body at the aforementioned points produce output signals controlling a phase switching system which reverses the direction of rotation of the motor. Reversal of the motor torque reverses the direction of movement of the moving body within a given travel and within a given time interval to full speed in the opposite direction. A stator current limiter provides positive coupling in an operative condition and no coupling in an inoperative condition with the motor running at full speed. The motor is selected so that the inertia of its rotor closely matches that of the moving body.