Deck 6: Electronic DC Motor Control

Question 1

With variable torque loads, the torque varies as the square of the speed.

Answer 1

True

Question 2

The armature power is typically controlled by an SCR that is turned on at different points in the waveform to adjust the voltage to the motor armature to control the speed.

Answer 2

True

Question 3

The electronic shear pin reacts to the amount-and rate -of current increase to the motor.

Answer 3

True

Question 4

In ____________________, a resistor is inserted in the circuit to act as an electrical load for the spinning armature as normal armature current is disconnected.

Question 5

In controlling motor operations, what are the two general schemes used to deliver the DC to the motor?

Question 6

____________________ is a form of electrical braking that provides a reversing voltage to the motor while it is still attached to the spinning load.

Question 7

What is the rationale for controllers having minimum speed settings?

Question 8

The ____________________ changes, or rectifies, the available AC to DC and adjusts the DC to control the motor operations.

Question 9

In a three-phase rectifier system, the DC level remains high and the ripple percentage is very low; therefore, the DC supply needs very little filtering.

Question 10

____________________ loads require more torque at low speed and less torque at high speed.

Question 11

What is the basic concept used in reducing the speed of a DC motor below base speed?

Question 12

In reference to a DC motor controller, what is a closed loop system?

Question 13

What is the purpose of a flywheel diode?

Question 14

The half-wave rectifier circuit requires two diodes and the use of a center-tapped secondary AC transformer.

Question 15

In regard to the firing of the SCR or the gate control, the ____________________ control method is the least costly control scheme and provides the least amount of control.