Resistor R 2 keeps Q 1 off as long as switch S 1 is open. R 1 limits the base current of Q 1 when S 1 is closed. S 1 can be a manual switch, a relay contact, an optocoupler, or a transistor. If you ...

Either the controller disconnecting means or motor disconnecting means required by 430.102 must be readily accessible [430.107]. The disconnecting means for the motor controller and/or the motor must ...

Features of the motor disconnect switches include: compliant with UL60947-4-1A rated up to 600V AC and 60V DC; 16, 30 and 40A; and 3-20 hp ...

Isolating problems in the control circuitIn Part 1 of this two-part series, we presented a 3-phase, 480VAC motor circuit with its associated controls (Figure). We stepped through a logical, systematic ...

This microcontroller-based control circuit adjusts the speed of a small permanent-magnet DC motor to one of four speeds as selected by a pair of photosensors.