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Chapter 20 Review Questions
Troubleshooting Electric Motors
October 2010 WEEK 8b
HVAC Tyrrell
1. True or False If a sleeve bearing fails in a small fractional horse power motor, the
motor is generally replaced
2. An open winding in an electric motor means
a. The winding is making contact with the motor frame
b. One winding is making contact with another one
c. A wire in the winding is broken
d. The centrifugal switch is open to the start winding
3. There is a short circuit in an electric motor winding when
a. There is an adverse weather condition
b. A winding conductor is worn bare and touches another part of the conductor
that is also bare
c. There is a defect in the centrifugal start switch
d. The motor will not start
4. An opened winding or a shorted winding can be determined with which of the
following instruments?
a. Voltmeter
b. Ammeter
c. Ohmmeter
d. Speedometer
5. Decreased resistance will cause the amperage to
a. Decrease
b. Increase
c. Not increase or decrease
d. None of the above
6. A_____________________ may be used to detect resistances in the millions of
ohms?
7. What resistor size do they recommend for discharging a capacitor?__________ohm
8. State the physical difference between the start and run capacitor
9. In 3 phase motors in good condition, should the resistance be the same across any 2
windings? - circle YES NO
10. Describe what may happen to an electric motor if the drive belt is too tight.
11. Loose electrical connections may result in a __________- in voltage and an
________________________ in amperage
12. Amperage is checked with a _______________
13. TRUE or FALSE - If a motor bearing is dry or worn out you can expect to see an
increase in amperage.
14. Tag the different components in this motor drawing
1. Start winding
2. Run winding
3. Capacitor
4. Centrifugal switch