Unit 20 Troubleshooting Electric Motors / HVAC
Unit 20 Review Questions and Review Test
1. If a sleeve bearing fails in a small, fractional horsepower motor, the motor is
generally replaced. ✔️ True.
2. An open winding in an electric motor means that ✔️ A wire in one
winding is broken.
3. There is a short circuit in an electric motor winding when ✔️ A
winding conductor is worn bare and touches another part of the conductor
that is also bare.
4. An open winding or a shorted winding can be determined with which
instrument? ✔️ An ohmmeter.
5. A decrease in resistance will cause the amperage to ✔️ Increase.
6. A ______ may be used to detect resistances in the millions of ohms. ✔️
Megohmmeter.
7. What size of resistor is recommended for shorting across an electrical
motor capacitor before checking with an ohmmeter? ✔️ A 20,000 ohm,
5 Watt resistor is recommended.
8. To determine the capacitance of a capacitor, a _____ should be used. ✔️
Capacitor tester.
9. State the physical differences between a run and a start capacitor. ✔️
A run capacitor is a metal, oil filled can, whereas a start capacitor is dry and
the shell is paper or plastic.
10. In a three-phase motor in good operating condition, the resistance
✔️ Should be the same across all three windings.
11. Describe what may happen to an electric motor if the drive belt is too tight.
✔️ A drive belt that is too tight will strain the bearings so that they wear out
prematurely.
Unit 20 Review Questions and Review Test
1. If a sleeve bearing fails in a small, fractional horsepower motor, the motor is
generally replaced. ✔️ True.
2. An open winding in an electric motor means that ✔️ A wire in one
winding is broken.
3. There is a short circuit in an electric motor winding when ✔️ A
winding conductor is worn bare and touches another part of the conductor
that is also bare.
4. An open winding or a shorted winding can be determined with which
instrument? ✔️ An ohmmeter.
5. A decrease in resistance will cause the amperage to ✔️ Increase.
6. A ______ may be used to detect resistances in the millions of ohms. ✔️
Megohmmeter.
7. What size of resistor is recommended for shorting across an electrical
motor capacitor before checking with an ohmmeter? ✔️ A 20,000 ohm,
5 Watt resistor is recommended.
8. To determine the capacitance of a capacitor, a _____ should be used. ✔️
Capacitor tester.
9. State the physical differences between a run and a start capacitor. ✔️
A run capacitor is a metal, oil filled can, whereas a start capacitor is dry and
the shell is paper or plastic.
10. In a three-phase motor in good operating condition, the resistance
✔️ Should be the same across all three windings.
11. Describe what may happen to an electric motor if the drive belt is too tight.
✔️ A drive belt that is too tight will strain the bearings so that they wear out
prematurely.
