Deck 23: Ac Inverter Drives

Question 1

With respect to 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 1

C

Question 2

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

Answer 2

True

Question 3

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

Answer 3

False

Question 4

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 5

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 6

The feedback device used in a pulse-width modulated variable voltage inverter is called a _____.

A) buffer amplifier
B) tachometer-generator
C) comparator
D) thermistor

Question 7

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 8

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) digital input inverter
D) SCR bridge inverter

Question 9

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

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

Question 10

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

Question 11

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

Question 12

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

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

Question 13

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

Question 14

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

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

Question 15

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