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