1. The starting of fairly large DC motors requires that current be increased gradually and at the same time resistance
must be inserted in series with the armature of the motor.
a. True
b. False
2. The current taken by the armature will be abnormally high unless the DC supply is increased gradually.
a. True
b. False
3. The counter emf developed by a motor is proportional to the speed of the motor unless the field is constant.
a. True
b. False
4. The total starting current is equal to the armature current plus the field current of 1 ampere.
a. True
b. False
5. Resistors may be rated in watts.
a. True
b. False
Name: Class: Date:
Unit 44 Use of Reduced Voltage for Starting
6. Two factors that limit the current taken by a motor armature from a given line are the counter emf and the ____
resistance.
a. starting b. ohmic
c. AC d. armature
7. The counter emf equals the applied voltage ____ the armature (IR) drop.
a. plus b. minus
c. times d. divided by
8. Excessive torque and heat may cause the insulation to overheat on starting and the ____ of the armature.
a. reduction b. movement
c. burning d. discoloration
9. The resistance in series with the armature reduces the starting armature current to approximately ____ times the
full-load current value.
a. 1.5 b. 3
c. 6 d. 12
10. The proper resistor can be selected by knowing the required resistance and the power value in ____.
a. ohms b. watts
c. amperes d. hertz
Name: Class: Date:
Unit 44 Use of Reduced Voltage for Starting