Question 1

All variable voltage inverters lack ____ protection, and they cannot handle oversized motors.&#10;A) overspeed&#10;B) overheating&#10;C) short-circuit&#10;D) open-circuit

Accepted Answer

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.&#10;A) variable voltage inverter&#10;B) current source inverter&#10;C) pulse-width modulated variable voltage inverter&#10;D) SCR

Accepted Answer

A current source inverter (CSI) controls the output current to meet the motor's needs while varying the voltage. This results in a torque-speed curve that is independent of the motor's parameters, making it ideal for high-performance motor control applications. Variable voltage inverters (A) do not control current, pulse-width modulated variable voltage inverters (C) control voltage and current simultaneously, and an SCR (D) is a type of thyristor used for power control, not motor control.

Question 3

With electrical power in an industrial environment, frequent outages, voltage spikes and sags, and electrical ____ are normal operating occurrences.&#10;A) overheating&#10;B) overhauling&#10;C) noise&#10;D) regulation

Accepted Answer

Electrical noise refers to random electrical signals that can interfere with the proper functioning of electronic equipment. It is a normal occurrence in industrial environments where multiple electrical devices are operating simultaneously. However, measures can be taken to minimize the impact of electrical noise, such as using shielded cables and grounding techniques. Overheating, overhauling, and regulation may also occur in industrial environments, but they are not necessarily normal occurrences or directly related to electrical power.

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.&#10;A) infrared&#10;B) optical&#10;C) thermometer&#10;D) thermostatic

Accepted Answer

The description provided is of a thermostatic switch, which is designed to open at a predetermined temperature. Infrared and optical sensors do not typically function based on temperature, and a thermometer is a device used to measure temperature rather than sense it.

Question 5

If the signal wires from feedback devices are routed next to high power cables, ____ can occur.&#10;A) interference&#10;B) hysteresis&#10;C) overhauling&#10;D) overheating

Accepted Answer

When signal wires from feedback devices are routed near high power cables, electromagnetic interference can occur. This interference can disrupt the signal and lead to errors in the feedback.

Question 6

An inverter converts the applied DC voltage to a(n) ____ DC voltage.&#10;A) reversing&#10;B) asynchronous&#10;C) rippling&#10;D) pulsating

Accepted Answer

The answer of An inverter converts the applied DC voltage...

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.&#10;A) current&#10;B) torque&#10;C) horsepower rating&#10;D) voltage rating

Accepted Answer

Inverters are used to vary the torque of the motor, which allows for better control over its speed and efficiency. Inverters can also provide a soft start for the motor, allowing it to start up smoothly and reduce stresses on the motor and other equipment.

Question 8

In a current source inverter, a large ____ is used in the DC link section.&#10;A) capacitor&#10;B) inductor&#10;C) resistor&#10;D) current source

Accepted Answer

In a current source inverter, a large inductor is used in the DC link section to ensure that the current remains constant or changes very slowly, which is essential for the operation of a current source inverter.

Question 9

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

Accepted Answer

In a variable voltage inverter, the DC voltage can be controlled based on the motor's needs, giving it a high level of flexibility and control. As a result, a variable voltage inverter is an excellent choice for many motor applications.

Question 10

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

Accepted Answer

The V/Hz ratio may vary depending on the motor design and operating conditions, but it should be kept within a certain range for optimal performance. This range is often referred to as the "constant V/Hz region".

Question 11

Flux vector drives operate by monitoring rotor position and changing the rotor's position as compared to its orientation to the ____.&#10;A) set position&#10;B) reference position&#10;C) stator field&#10;D) current direction

Accepted Answer

The answer of Flux vector drives operate by monitoring rotor...

Question 12

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

Accepted Answer

The answer of An AC drive has three basic sections:...

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.

Accepted Answer

The answer of A typical DC link, also called a...

Question 14

What is the feedback device used in a pulse-width modulated variable voltage inverter called?&#10;A) Buffer amplifier&#10;B) Tachometer-generator&#10;C) Comparator&#10;D) Thermistor

Accepted Answer

The answer of What is the feedback device used in...

Question 15

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

Accepted Answer

The answer of In an AC inverter drive, the four...

Deck 23: Ac Inverter Drives