Motor Control, Level III Lesson 1: DC Motor Control
EXPECTED QUESTIONS WITH VERIFIED ANSWERS
Question 1.
The ? motor can be started manually with a rheostat.
ANSWER
b. DC
Question 2.
Most new or upgraded DC systems use what type of starting method?
ANSWER
b. electronic DC drive
Question 3.
When starting a DC motor with a rheostat, the current at the field winding is ? and the current at the
armature is ? .
ANSWER
b. high / low
Question 4.
During the operation of a DC rheostat motor starter, the resistance is ? in the field winding and ? in the
armature until the motor is brought up to full speed.
ANSWER
b. increased / reduced
Question 5.
Most DC motor contactors consist of ? set(s) of contacts.
ANSWER
a. one
1/5
, Question 6.
The standard coil voltage ratings for DC contactors are 12, 24, 48, 120, and ? .
ANSWER
a. 240 V DC
Question 7.
DC currents stay ? the zero axis and maintain a constant current flow to the motor.
ANSWER
a. above
Question 8.
It is important to make and break contacts as quickly as possible to extinguish the arc promptly and to
extend the life of the contacts and contactor.
ANSWER
True
Question 9.
Arc chutes typically absorb ? than 80% of the energy released during the interruption of current flow
as the contacts open.
ANSWER
a. greater
Question 10.
The magnetic ? coil produces a magnetic field between the breaking contacts that forces the arc up,
increasing the length of the arc and causing it to dissipate faster.
ANSWER
a. blowout
Question 11.
Because solid-state drives do not use ? , energy is not wasted in the form of heat.
ANSWER
c. resistors
2/5
EXPECTED QUESTIONS WITH VERIFIED ANSWERS
Question 1.
The ? motor can be started manually with a rheostat.
ANSWER
b. DC
Question 2.
Most new or upgraded DC systems use what type of starting method?
ANSWER
b. electronic DC drive
Question 3.
When starting a DC motor with a rheostat, the current at the field winding is ? and the current at the
armature is ? .
ANSWER
b. high / low
Question 4.
During the operation of a DC rheostat motor starter, the resistance is ? in the field winding and ? in the
armature until the motor is brought up to full speed.
ANSWER
b. increased / reduced
Question 5.
Most DC motor contactors consist of ? set(s) of contacts.
ANSWER
a. one
1/5
, Question 6.
The standard coil voltage ratings for DC contactors are 12, 24, 48, 120, and ? .
ANSWER
a. 240 V DC
Question 7.
DC currents stay ? the zero axis and maintain a constant current flow to the motor.
ANSWER
a. above
Question 8.
It is important to make and break contacts as quickly as possible to extinguish the arc promptly and to
extend the life of the contacts and contactor.
ANSWER
True
Question 9.
Arc chutes typically absorb ? than 80% of the energy released during the interruption of current flow
as the contacts open.
ANSWER
a. greater
Question 10.
The magnetic ? coil produces a magnetic field between the breaking contacts that forces the arc up,
increasing the length of the arc and causing it to dissipate faster.
ANSWER
a. blowout
Question 11.
Because solid-state drives do not use ? , energy is not wasted in the form of heat.
ANSWER
c. resistors
2/5
