AC Theory Transformer Applications and Motors

On the resistance start induction run motor there are two windings , the starting winding and the running winding . At start up , both windings are connected in parallel to the single - phase line . Once the motor accelerates to 2 / 3rds or 3 / 4ths of the rated speed , a ________ ________ _________ the starting winding automatically.

Centrifugal Switch Disconnects

The type of motor that is wound for two to five steps of speed and is used to operate fans and squirrel-cage blowers is called the ___________ fan motor.

Multispeed.

The type of motor that operates based on the principal that like poles repel is called the ________.

Repulsion Motor

A voltmeter is connected to a circuit in __________ to measure the pressure of voltage.

parallel

The type of transformer that has relatively small VA ratings and is used for doorbell systems and control equipment is called a _______ _______.

potential transformer.

__________ is the number of revolutions per minute by which the rotor falls behind the speed of the rotating field of the stator.

Slip

The __________ produced by an induction motor depends upon the strengths of the stator and rotor fields and the phase relationship between the fields.

The torque

Interchanging the connections of any ______ of the three line leads feeding to the stator windings will reverse the direction of rotation of a three - phase motor .

Two

The rotating member of most motors is called ________.

the rotor.

Smaller values of percent slip means that the motor has better speed regulation. The percent slip of most squirrel-cage induction motors varies from ______ to ______.

2% to 5%.

Most three-phase motors are started with the rated line voltage, which means that the starting surge of current reaches a value as high as _______ to _______ times the full load current rating of the motor.

3 to 5

When a motor is started at 50% less voltage than it is rated, the amount of torque output of the motor is reduced by _______ percent.

75 percent.

The type of motor that has a capacitor connected in series with the starting windings and after the motor reaches 75 % of the rated speed a centrifugal switch opens and the starting winding and capacitor are disconnected from the line , are used in refrigeration units , compressors , oil burners and small machine equipment is called the ___________ __________ _____________ _________ Motor.

Capacitor Start Induction Run Motor

The type of motors that provides a means of electrically interconnecting two or more remote points of a system and give automatic synchronized control or indication at one point with respect to the other point , are used to give indications of positions of remote devices such as swing bridges , gates or valves , are called __________ motors .

Selsyn

The speed at which the magnetic field rotates is known as the _________ ___________

synchronous speed.

The stationary member of most motors is called ________

the stator,

The type of three - phase ac motor that operates at a constant speed from no load to full load is called the ____________ ___________.

Synchronous Motor

The type of small single - phase synchronous motor used in many timing applications such as electric clocks and time switches is the _______ or _________ _________ clock motor.

Warren ( or General Electric )

The type of transformer that is used on services and in clamp-around meters is called a _______ ________.

current transformer.

The type of motor that has the starting winding and a capacitor connected into the circuit at all times, has good starting torque and unity power factor is called the ________ ________ ________ ________ motor.

capacitor start capacitor run motor.

The principal of operation of all three-phase motors is the __________ ___________ field.

rotating magnetic

The type of motor that can operate on either AC or DC is called the ___________.

Universal Motor

The type of three-phase induction motor that is used for variable speed applications is called the ________ _________ induction motor.

Wound Rotor

The type of transformer that uses only one winding for both the primary and secondary is called an ________________.

autotransformer.

An ammeter is connected into a circuit in ________ to measure the current flow.

series

A wattmeter is connected into a circuit in ________ & ________ to measure the power being consumed.

series and parallel

The type of three-phase induction motor that is used for constant speed applications is called the __________ __________ induction motor.

squirrel cage

The use of small _________ speed motors has increased greatly in the past few years since these motors are used to operate light loads such as ceiling fans and blower motors.

variable speed motors