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A relay is an electrically operated switch. It consists of a set of input terminals for a single or multiple control signals, and a set of operating contact terminals. The switch may have any number of contacts in multiple contact forms, such as ________ contacts, _______ contacts, or combinations thereof.It uses a low current on/off to control __________ current on/off.

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A single phase ac induction motor has two windings, one is a run winding and the other is called a start winding. Strat winding can only work for a very short time to avoid overheated. A _____________ switch is installed inside motor to disconnect the strat winding when the motor speed reached 75% RPM.

An induction motor's rotor can be either wound type or ????????-???? type.

The common weakness for a single phase induction motor is it has a very small start torque. To increase its start torque, a strating _____________is connected in series into start winding which will be disconnected when the speed reaches 75% RPM by centrifugal switch.

To change the speed of a DC motor, you can change the applied DC____________. To change the speed of an AC induction motor you must change the ____________ of the AC power supplied.

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