Question 1

A split-phase has a ____ winding and a ____ winding.

Accepted Answer

A split-phase motor has a start winding and a run winding, which are used to create a phase shift for starting the motor.

Question 2

When a general duty split-phase motor reaches approximately 75% of its operating speed, the start winding is de-energized by a ____.

Accepted Answer

When a general duty split-phase motor reaches approximately 75% of its operating speed, the centrifugal switch is activated and opens the start winding circuit, thus de-energizing the start winding.

Question 3

A permanent split capacitor (PSC) motor that is running and up to speed will have the start winding ____.

Accepted Answer

The start winding in a permanent split capacitor (PSC) motor remains energized even when the motor is running and up to speed, unlike in other motor types where the start winding is removed or disconnected after startup. This is because the capacitor in a PSC motor is permanently connected in series with the start winding, providing continuous phase shift for better running efficiency.

Question 4

A current magnetic relay opens and closes its contacts based on the ____.

Accepted Answer

Magnetic relays operate based on the current in the electromagnetic coil, which creates a magnetic field that attracts the armature to make or break the circuit. Therefore, the correct choice is D) current in the run winding.

Question 5

The positive temperature coefficient resistor start device is a type of ____.

Accepted Answer

A positive temperature coefficient resistor (PTC) is a type of variable resistor that increases its resistance with an increase in temperature, making it a correct choice for this description.

Question 6

When a Capacitor Start, Capacitor Run (CSCR) motor initially starts, what is the total capacitance acting on the motor? (Assume the run capacitor is 5 microfarads and the start capacitor is 20 microfarads, if present.)

Accepted Answer

When a Capacitor Start, Capacitor Run (CSCR) motor initially starts, both the start capacitor and run capacitor are in circuit, so the total capacitance acting on the motor will be the sum of both the capacitors, which is 20 + 5 = 25 microfarads. Therefore, the correct option is D, i.e. 25 microfarads.

Question 7

The starting device usually used on single phase, fractional horsepower motors requiring low starting torque is the ____.

Accepted Answer

Current relays are commonly used as starting devices for single-phase, fractional horsepower motors that do not require high starting torque. They operate based on the current flowing through the motor during startup.

Question 8

A permanent split-capacitor motor has a ____.

Accepted Answer

A permanent split-capacitor motor only has a run capacitor. It does not require a start capacitor because the design of the motor allows it to start and run using only a run capacitor.

Question 9

Three phase motors have ____.

Accepted Answer

Three-phase motors have run windings only, as they do not require separate start windings or start switches like single-phase motors. The three-phase power supply provides a rotating magnetic field that starts the motor.

Question 10

A motor's speed is determined by ____.

Accepted Answer

The number of motor poles determines the speed of the motor. The more poles a motor has, the slower it rotates, and vice versa. Size, voltage, and amperage all affect the motor's performance and power, but do not directly determine the speed of the motor.

Question 11

The magnetic fields generated in the rotor and stator of a motor causes the rotor to be pushed around the shaft.

Accepted Answer

The answer of The magnetic fields generated in the rotor...

Question 12

When a Capacitor Start Induction Run (CSIR) motor is running and up to speed, what is the total capacitance acting on the motor? (Assume the run capacitor is 5 microfarads and the start capacitor is 20 microfarads, if present.)

Accepted Answer

When a Capacitor Start Induction Run (CSIR) motor is up to speed, the start capacitor is disconnected from the circuit, leaving only the run capacitor (5 microfarads) acting on the motor.

Question 13

The centrifugal switch mounted on the shaft of a split-phase motor has a normally closed contact.

Accepted Answer

The centrifugal switch in a split-phase motor is normally closed to connect the start winding and is opened by centrifugal force as the motor reaches a certain speed, disconnecting the start winding from the circuit.

Question 14

A split-phase motor that has a current relay and a start capacitor is called a(n) ____ motor.

Accepted Answer

A split-phase motor that has a current relay and a start capacitor but does not keep the capacitor in the circuit once the motor reaches a certain speed is known as a Capacitor Start, Induction Run (CSIR) motor. This type of motor uses the capacitor for starting torque but runs as an induction motor once it is up to speed.

Question 15

In order to change the direction of rotation of a split-phase motor, the technician must change the direction of current flow through the start winding.

Accepted Answer

This is correct as the start winding is responsible for initiating the rotation of the motor and changing the direction of current flow through it will reverse the direction of rotation.

Question 16

The heavier the load on an operating motor, the greater the amount of slip.

Accepted Answer

This statement is true according to the concept of slip in electrical motors. As the motor operates under heavier load, the rotor speed decreases, and the amount of slip increases.

Question 17

Capacitors wired in series with the starting winding provide a(n) ____.

Accepted Answer

Capacitors wired in series with the starting winding provide a greater starting torque.

Question 18

The shaded pole motor ____.

Accepted Answer

The shaded pole motor has little starting torque compared to other types of single-phase motors.

Question 19

The start windings have ____.

Accepted Answer

The start windings typically have more turns than the run windings to create a higher resistance, which helps in developing a starting torque by producing a phase shift between the currents in the start and run windings.

Question 20

Start windings are placed ____ with the run windings.

Accepted Answer

Start windings are placed slightly out of phase with the run windings to create a phase difference that helps in starting the motor.

Quiz 17: Types of Electric Motors

A split-phase has a winding and a winding.