Deck 23: Ac Inverter Drives

Question 1

All variable voltage inverters lack ____ protection, and they cannot handle oversized motors.

A) overspeed
B) overheating
C) short-circuit
D) open-circuit

Answer 1

C

Question 2

The ____ is a type of inverter drive in which the current is controlled while the voltage is varied to satisfy the motor's needs.

A) variable voltage inverter
B) current source inverter
C) pulse-width modulated variable voltage inverter
D) SCR

Answer 2

B

Question 3

With electrical power in an industrial environment, frequent outages, voltage spikes and sags, and electrical ____ are normal operating occurrences.

A) overheating
B) overhauling
C) noise
D) regulation

Answer 3

C

Question 4

The sensors used to sense motor temperatures consist of a nonadjustable ____ switch that is normally closed and opens when the temperature rises to a certain level.

A) infrared
B) optical
C) thermometer
D) thermostatic

Question 5

If the signal wires from feedback devices are routed next to high power cables, ____ can occur.

A) interference
B) hysteresis
C) overhauling
D) overheating

Question 6

An inverter converts the applied DC voltage to a(n) ____ DC voltage.

A) reversing
B) asynchronous
C) rippling
D) pulsating

Question 7

Inverters are used not only to vary the speed of the squirrel-cage motor, but also to vary its ____, start the motor slowly and smoothly, and increase the motor's efficiency.

A) current
B) torque
C) horsepower rating
D) voltage rating

Question 8

In a current source inverter, a large ____ is used in the DC link section.

A) capacitor
B) inductor
C) resistor
D) current source

Question 9

In a variable voltage inverter, the DC voltage is controlled, and the DC is free to respond to the motor needs.

Question 10

For proper motor operation, the V/Hz ratio (also called the V/f ratio) must be kept equal to one.

Question 11

Flux vector drives operate by monitoring rotor position and changing the rotor's position as compared to its orientation to the ____.

A) set position
B) reference position
C) stator field
D) current direction

Question 12

An AC drive has three basic sections: the converter, the DC filter, and the output.

Question 13

A typical DC link, also called a DC filter or DC bus, is a filter circuit composed of an inductor and a capacitor.

Question 14

What is the feedback device used in a pulse-width modulated variable voltage inverter called?

A) Buffer amplifier
B) Tachometer-generator
C) Comparator
D) Thermistor

Question 15

In an AC inverter drive, the four main areas of possible problems are the same as those in a DC drive.