Unit 17 Types of Motors
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.)
25 microfarads
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.)
5 microfarads
A split-phase motor that has a current relay and a start capacitor is called a(n) ____ motor.
Capacitor Start, Induction Run (CSIR)
The contact(s) in a current type starting relay are normally closed
False
On a potential relay, the coil is connected between terminals 2 and ____________________.
Five
The shaded pole motor ____.
Has little starting torque.
The coil of a potential relay has ____________________ resistance.
High
When not air cooled, the heat generated by the motor in a hermetic motor-compressor assembly is removed by what?
It is removed by refrigerant vapor.
The windings of the relay coil in a current relay has very low resistance. Why?
It would drop too much voltage and interfere with the run winding's power consumption needs.
What is meant by the "phase angle" in an alternating current circuit?
Phase angle refers to the amount by which the current leads or lags the voltage.
The rotating portion of an electric motor is called the ____________________.
Rotor
The difference between synchronous speed and full load speed is called ____________________.
Slip
A motor that has copper bars in the rotor is classified as a(n) ____________________ type.
Squiller cage
The ______________ is a winding that, when energized, will generate a magnetic field as there will be current flowing through it.
Stator
By what means does a two speed compressor motor accomplish the speed change?
The automatic changeover is accomplished with the space temperature thermostat and the proper compressor contactor for the proper speed.
. The heavier the load on an operating motor, the greater the amount of slip
True
A Capacitor Start Capacitor Run (CSCR) motor that is wired with a potential relay will have the start winding energized when the relay's contacts open.
True
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.
True
Once the start winding and the start capacitor have been removed for the circuit, the motor will continue to operate with only the run winding energized.
True
The centrifugal switch mounted on the shaft of a split-phase motor has a normally closed contact.
True
The contact(s) in a potential type starting relay are normally closed.
True
The microfarad rating of the run capacitor is much lower than that of the start capacitor for any given motor application.
True
The resistances of the windings in a three phase motor are all equal.
True
When a general duty split-phase motor reaches approximately 75% of its operating speed, the start winding is de-energized by a ____.
centrifugal switch
A current magnetic relay opens and closes its contacts based on the ____.
current in the run winding
The starting device usually used on single phase, fractional horsepower motors requiring low starting torque is the ____.
current relay
A permanent split capacitor (PSC) motor that is running and up to speed will have the start winding ____.
energized
The magnetic fields generated in the rotor and stator of a motor causes the rotor to be pushed around the shaft.
false
. Capacitors wired in series with the starting winding provide a(n) ____.
greater starting torque
The start windings have ____.
more turns than the run windings
. A motor's speed is determined by ____.
number of motor poles
A permanent split-capacitor motor has a ____.
run capacitor only
Three phase motors have ____.
run windings only
Start windings are placed ____ with the run windings.
slightly out of phase
A split-phase has a ____ winding and a ____ winding.
start, run
The positive temperature coefficient resistor start device is a type of ____.
variable resistor