Abstract: A reduced voltage starter for electric motors comprises a controller, and a plurality of semiconductor switches to selectively connect a power source to a motor. The controller is configured to apply a first voltage ramp to provide a controllable fraction of the full line voltage to the motor, while maintaining a current flow to be within a programmable current limit during motor startup. The controller is further configured to implement a bumpless force transition, by applying a second voltage ramp when the speed of the motor is below the rated motor speed, and force transition criteria correlated with overheating of the semiconductor switches and/or a connected load are met.

Abstract: An apparatus includes a magnetometer-based current sensor (e.g., a Hall-effect or fluxgate-based current sensor) configured to sense a magnetic field generated by a current in at least one conductor connecting a motor drive output to a motor and to responsively produce a first current sense signal and a magnetometer-based voltage sensor (e.g., a Hall-effect or fluxgate-based voltage sensor) configured to sense a magnetic field generated in response to a voltage of the at least one conductor and to responsively produce a first voltage sense signal. The apparatus further includes a signal conversion circuit configured to receive the first current sense signal and the first voltage sense signal and to generate a second current sense input and a second voltage sense input for provision to a current sense input and a voltage sense input, respectively, of a motor protection relay that protects the motor.

Abstract: An apparatus includes a magnetometer-based current sensor (e.g., a Hall-effect or fluxgate-based current sensor) configured to sense a magnetic field generated by a current in at least one conductor connecting a motor drive output to a motor and to responsively produce a first current sense signal and a magnetometer-based voltage sensor (e.g., a Hall-effect or fluxgate-based voltage sensor) configured to sense a magnetic field generated in response to a voltage of the at least one conductor and to responsively produce a first voltage sense signal. The apparatus further includes a signal conversion circuit configured to receive the first current sense signal and the first voltage sense signal and to generate a second current sense input and a second voltage sense input for provision to a current sense input and a voltage sense input, respectively, of a motor protection relay that protects the motor.