CH 17
T/F the contacts in a current type starting relay are normally closed
false
capacitors wired in series with the starting winding provide a ____
greater starting torque
the shaded pole motor ____
has a little starting torque
the coil of a potential relay has ____ resistance
high, over 1kohms
the start windings have ____
more turns than the run windings
a motors speed is determined by _____
number of motor poles
T/F a cap start cap run CSCR motor that is wired with a potential relay will have the start winding energized when the relays contacts open
true
T/F in order to change the direction of rotation of a split phase motor, the technician must change the direction fo current flow through the start winding
true
T/F once the start winding and the start cap have been removed for the circuit, the motor will continue to operate with only the run winding energized
true
T/F the centrifugal switch mounted on the shaft of a split phase motor has a normally closed contact
true
T/F the contacts in a potential type starting relay are normally closed
true
T/F the microfarad rating of the run cap is much lower than that of the start cap for any given motor application
True
T/F 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
on a potential relay, the coil is connected between terminals 2 and ____
1
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 MFD and the start capacitor is 20 MFD)
25 MFD
when a capacitor start induction run motor is running and up to speed, what is the total capacitance acting on the motor? assume the run cap is 5 MFDs and the start cap is 20 MFDs
5 microfarads
the _____ is a winding that, when energized, will generate a magnetic field as there will be current flowing through it
stator
three phase motors have ____
three start and three run windings for each phase
T/F the heavier the load on an operating motor, the greater the amount of slip
true
the difference between synchronous speed and full load speed is called ______
slip
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
T/F the magnetic fields generated in the rotor and stator of a motor causes the rotor to be pushed around the shaft
false
a split phase motor that has a current relay and a start capacitor is called a ____ motor
capacitor start, induction run CSIR
the rotating portion of an electric motor is called the ____
rotor
a permanent split capacitor motor has a ____
run capacitor only
start windings are placed _____ with the run windings
slightly out of phase
a motor that has copper bars in the rotor is classified as a _____ type
squirrel
a split phase has a ____ winding and a ____ winding
start, run
the positive temperature coefficient resistor start device is a type of ____
variable resistor
