1. Packaged variable speed drives generally operate on AC.
a. True
b. False
2. The AC service in industrial plants can not be converted to direct current for use with DC variable-speed controls.
a. True
b. False
3. The field of the DC generator can be reversed manually or automatically with a resulting reversal of the motor
rotation.
a. True
b. False
4. A controlling tachometer feedback signal may be driven by the DC motor driveshaft.
a. True
b. False
5. The generator field resistance can be changed manually or automatically by latching relays.
a. True
b. False
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Name: Class: Date:
Unit57DCVariableSpeedControl—MotorDrives
6. In the Ward Leonard system, a DC shunt generator with field control is driven by a(n) ____.
a. induction motor b. transformer
c. precision controller d. chain drive
7. Electricity can be generated electromagnetically for heavy power consumption only if the following are present: a
magnetic field, a conductor, and the ____ motion of the two.
a. relative b. down
c. centrifugal d. up
8. The motor-generator set has one inherent advantage over rectifier-type DC supplies, that is, ____.
a. the fact of being relocatable b. being easy to replace when they fail
c. the ability to regenerate d. being much less expensive
9. To meet specific operating requirements, the packaged variable-speed control drives can be furnished with a variety
of modifications, including provisions for ____.
a. disc braking b. reset speed control
c. resistance regulation d. multimotor drive
10. Some control schemes eliminate the standard exciter and provide other methods of energizing the generator and
____.
a. exciter b. motor fields
c. remote unit d. receiving unit
Name: Class: Date:
Unit57DCVariableSpeedControl—MotorDrives