Modern Refrigeration & AC Chapter 15

Which type of single-phase induction motor has the starting torque to start under heavy loads?

Capacitor-start, capacitor-run motor

Which of the following are the three motor terminals found on a single-phase hermetic compressor?

Common, starting, and running

Three-phase motors are commonly _____________motors because of the way their stator windings are arranged in pairs

Dual-voltage

The speed of ac motors is primarily determined by which two factors?

Frequency and number of field poles

The current that a motor draws as power is first applied at start-up is the motor's

Locked Rotor Amperage

Instead of coils of wire, a squirrel cage rotor has _________ mounted on an iron core

Metal Bars

Important motor information such as rated voltage, time rating, insulation class, frequency, phase, and horsepower can be found on the

Motor Nameplate

The two main parts of a motor are the

Rotor and Stator

Start capacitors and run capacitors are added to the _________ circuit of an induction motor for additional torque

Start Winding

In which two parts of an HVACR system are motor-driven fans typically used?

The Condenser and Evaporator

Which of the following best explains the relationship between the rotor and the stator in an ac induction motor?

The magnetic field is generated by the stator induces current in the rotor, which causes the rotor to generate its own magnetic field.

Capacitors are used to generate higher starting ________because they cause larger phase displacement between the start and run windings

Torque

On a capacitor-start, induction-run motor, a centrifugal switch or relay disconnects the _________ when the motor reaches about 75% of its rated speed

both the start winding and the start capacitor

Although permanent split capacitor motors have low starting torque, they operate the same as a _____________motor operates in running mode, but not starting mode.

capacitor-start, capacitor-run

Split-phase motors use a (n)______________to disconnect the start windings as the motor approaches running speed

cetrifugal switch

The magnetic field generated in the rotor induces a voltage called _________________that has a polarity opposite of the applied

counter emf(electromotive force)

Advantages of ECMs (electronically commutated motor) include the following, EXCEPT

easily replaceable brushes

A VFD (variable frequency drive) controls an induction motor's speed by changing

frequency

Slip is the difference between a motor's synchronous speed and its rated ________speed

full load

A motor's start winding has a higher inductance value than the run winding because it is made of

more coil turns

To reverse a three-phase motor's direction of rotation, a technician must disconnect two power leads and connect each one to the

other lead's terminal

In an electronically commutated motor, the rotor is made of

permanent magnets

Start and run windings cause_____________which is when the current in the start winding is out of phase with the run winding

phase splitting

A dual voltage, three-phase motor can be wired for high voltage by connecting the field windings in

series

As the voltage level decreases in a shaded-pole motor's field windings, the electromagnetic field becomes centered over the

shaded pole