Deck 35: Solid-State Dc Motor Controls

Question 1

How is a DC motor operated below normal?

Answer 1

The motor can be operated at below normal speed by applying rated voltage to the field and reduced voltage to the armature.

Question 2

An electrotachometer is connected to the ____________________.

Answer 2

motor shaft

Question 3

Output voltage control is achieved by ____________________ the SCRs.

Answer 3

phase shifting

Question 4

Speed control of a DC motor is much smoother if two separate ____________________, which convert the AC voltage to DC voltage, are used to control the motor instead of resistors connected in series with the armature.

Question 5

If load is added to a motor, the motor speed increases.

Question 6

Why do most solid-state DC motor controls use some method to limit the current to a safe value?

Question 7

The armature of a large DC motor has high resistance.

Question 8

In a field failure control, what happens if the voltage falls below a certain level?

Question 9

A very common method of detecting motor speed is with the use of a(n) ____________________.

Question 10

If current flow through the shunt field is interrupted, a compound wound, DC motor will become a series motor and race to high speeds.

Question 11

The shunt field power supply is generally designed to remain turned on even when the main (armature) power supply is turned off.

Question 12

The greatest advantage of using direct current motors is their variable ____________________ characteristic.

Question 13

A DC motor is generally operated at or below normal speed.

Question 14

How is normal speed for a DC motor obtained?

Question 15

What is an electrotachometer?