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Motor ch 18
Troubleshooting Motors
| Question | Answer |
|---|---|
| 1. A ___ occurs when current leaves its normal path and travels to the frame of the motor. | ground fault circuit |
| 2. A special zip-sealed jacket placed around a motor provides protection from pests. True or False | True |
| 3. ___ is the most common causes of motor failure. | Overloading |
| 4. ___ is a power supply problem that occurs when one of the 3-phase line leading to a 3-phase motor no longer delivers voltage to the motor. | Single phasing |
| 5. Single phasing causes less damage to coils than voltage unbalance. True or False | False |
| 6. Belt deflection should equal about ___ per inch of span. | 1/64" |
| 7. A ___ is a temporary condition where a higher-than-normal voltage exists on one or more of the power lines. | voltage surge |
| 8. A motor is ___ when it draws more than rated current. | overloaded |
| 9. If the span between the center of the drive pulley and the center of the driven pulley is 24", the belt deflection should be | 3/8" 24 * (1/64) |
| 10. Belt tension adjustments are usually accomplished by moving the drive component away from or closer to the driven component. True or False | True |
| 11. A ___ detect insulation failure on wires by measuring resistance values during high-voltage test condition. | megohmmeter |
| 12. For solid-state starting, the voltage during starting should be __ the incoming measured voltage. | 15% - 50% less than |
| 13. ____ is a medium in which an electric field i maintained with little or no outside energy supply. | Dielectric material |
| 14. A ___ wears faster than any other component of a DC motor. | brush |
| 15. Whenever more than 1%___ is measured, the power system should be checked for excessive loads connected to one line. | voltage unbalance |
| 16. The starting winding of a ___ motor is automatically removed by a centrifugal swithc as the motor accelerates. | split-phase |
| 17. Before checking windings of a DC ___ motor, the shunt winding need to be isolated from the armature windings. | compound |
| 18. For __ starting, the starting voltage should be 50%, 65%, or 80% of the incoming line voltage. | autotransformer |
| 19. A ___ can be used to test a mechanical switch for an open circuit. | DMM |
| 20. A ground fault is caused when the ___ breaks down or is damaged and touches the metal frame of a motor. | insulation |
| 21. A dual-voltage, wye-connected motor has ___separated stator winding circuits. | 4 |
| 22. Generally, a dual-voltage, delta-connected motor has ___ separate stator winding circuits. | 3 |
| 23. All three types of DC motors have a different armature and frame but the way the field coil and armature are connected is the same. True or False | False |
| 24. Terminal markings F1 and F2 always indicate the ___ leads of a DC motor. | shunt |
| 25. A possible cause for a shaded-pole motor that will not start is a ___. | blown fuse or open CB |
| 26. When troubleshooting a split-phase motor, the problem has been isolated to the start and run windings. An ohmmeter reads 0 across the windings. What does this mean? | short |
| 27. Read the question on page 90 | T1 and T4 re wound |
Created by:
JoshHampton