1. When greasing motor bearings, the proper procedure is to
b. disassemble the motor and remove the bearings
grease a warm and running motor and remove the vent plug
leave the bearing housing as full of grease as possible.
wait until the motor has been stopped for some time. d.
2. As part of routine maintenance, brushes should be
a. Inspected.
b. replaced if they show any wear.
removed and cleaned off. C.
d. seated into the commutator.
3. An Induction motor is most likely to be damaged by
Low voltage.
b. high starting current.
C. a supply system power factor of less than 1.
running it at synchronous speed. d.
4. When a motor fails, the first step in the troubleshooting method is to
a. isolate the problem to the motor or load
b. check out all components systematically, beginning at the power supply.
list probable causes. C.
Investigate the symptoms of failure in detail. d.
5. Explosion-proof motors will not
a. cause an explosion even if something inside ignites.
b. allow potentially explosive gases to accumulate inside.
be damaged by an external explosion.
burn out no matter how they are overloaded. d.
6. Reversing a three-phase motor involves
interchanging any two of the three lines.
reversing the connections to the rotor, b.
Interchanging the wye and delta windings.
reversing the polarity of all windings. d.
7. Keeping a motor clean
a. allows it to produce more power.
makes it more efficient. b.
helps it run cooler.
d. reduces friction.
8. The resistance reading through most motor windings
b.
should slowly build up to at least several megohms.
Is too low for a standard ohmmeter to detect
will be infinite if the insulation is good. C.
Is only a few ohms. d.
9. If the three phase voltages to a motor are equal, but the currents are not,
b. there is a problem in the supply.
the voltages are not phased correctly.
a motor winding is defective.
the motor is overloaded, d.
10. The insulation class of a motor is an indication of
a. how much voltage the insulation can stand.
b. 0000
the temperature the insulation can tolerate without damage.
The motor's resistance to environmental moisture and chemicals.