Question 1

Speed regulation is accomplished by sensing the speed of the motor and____________ .

Accepted Answer

A) connecting current transformers to the input of the drive 
B) feeding this information back to the drive 
C) sensing the increase in current as load is added 
D) adjusting this speed 
A) connecting current transformers to the input of the drive 
B) feeding this information back to the drive 
C) sensing the increase in current as load is added 
D) adjusting this speed B

Question 2

DC motors are still used in many industries.

Accepted Answer

A) True 
 B)False  True

Question 3

Inverter-rated motors generally have phase paper _____________.

Accepted Answer

A) to provide a larger surface area 
B) to provide continuous cooling for the motor 
C) to help draw air through the motor 
D) added to the terminal leads 
A) to provide a larger surface area 
B) to provide continuous cooling for the motor 
C) to help draw air through the motor 
D) added to the terminal leads D

Question 4

Drives using IGBTs generally use ____________to rectify the AC voltage into DC.

Accepted Answer

A) SCRs 
B) GTOs 
C) diodes 
D) thyristors 
A) SCRs 
B) GTOs 
C) diodes 
D) thyristors

Question 5

Many variable-frequency drives can provide the____________ characteristic that is so desirable in DC motors.

Accepted Answer

A) low-speed torque 
B) low power factor 
C) high-speed torque 
D) high power factor 
A) low-speed torque 
B) low power factor 
C) high-speed torque 
D) high power factor

Question 6

IGBTs have an insulated gate different from all types of field effect transistors (FETs).

Accepted Answer

A) True 
 B)False

Question 7

Variable-frequency drives control motor speed by controlling the frequency of the power supplied to the motor.

Accepted Answer

A) True 
 B)False

Question 8

The magnet wire used in the construction of inverter rated motor windings has a lower rated insulation than other motors.

Accepted Answer

A) True 
 B)False

Question 9

The primary purpose of a variable-frequency drive is to provide speed control for an AC motor.

Accepted Answer

A) True 
 B)False

Question 10

The values of current limit, speed, ramping time, and so on for variable-frequency drives are___________ .

Accepted Answer

A) more difficult to adjust 
B) less accurate than adjusting trim resistors 
C) hard to read 
D) programmed into the unit 
A) more difficult to adjust 
B) less accurate than adjusting trim resistors 
C) hard to read 
D) programmed into the unit

Exam 55: Ac Adjustable Frequency Drives

Speed regulation is accomplished by sensing the speed of the motor and____________ .

DC motors are still used in many industries.

Inverter-rated motors generally have phase paper _____________.

Drives using IGBTs generally use ____________to rectify the AC voltage into DC.

Many variable-frequency drives can provide the____________ characteristic that is so desirable in DC motors.

IGBTs have an insulated gate different from all types of field effect transistors (FETs).

Variable-frequency drives control motor speed by controlling the frequency of the power supplied to the motor.

The magnet wire used in the construction of inverter rated motor windings has a lower rated insulation than other motors.

The primary purpose of a variable-frequency drive is to provide speed control for an AC motor.

The values of current limit, speed, ramping time, and so on for variable-frequency drives are___________ .

General Principles of Electric Motor Control

Fractional and Integral Horsepower Manual Motor Starters

Magnetic Starters

Symbols

Interpretation and Application of Simple Wiring and Elementary Diagrams

Push Buttons and Control Stations

Relays

Contactors

Timing Relays

Pressure Switches and Regulators

Float Switches

Flow Switches

Limit Switches and Proximity Control

Phase Failure Relays

Solenoid Valves

Temperature Switches

Two-Wire Controls

Three-Wire and Separate Controls

Hand-Off Automatic Controls

Multiple Push-Button Stations

Interlocking Methods for Reversing Control

Sequence Control

Jogging Inching Control Circuits

Time-Delay Low-Voltage Release Relay

The Motor and Starting Methods

Primary Resistor-Type Starters

Autotransformer Starters

Part Winding Motor Starters

Automatic Starters for Star-Delta Motors

Ac Solid-State Reduced Voltage Controller

Controllers for Two-Speed Two-Winding 28separate Winding29 Motors

Two-Speed One-Winding 28consequent Pole29 Motor Controller

Four-Speed Two-Winding 28consequent Pole29 Motor Controller

Wound Rotor Motors and Manual Speed Control

Push-Button Speed Selection

Automatic Acceleration for Wound Rotor Motors

Automatic Speed Control for Wound Rotor Motors

Solid-State Adjustable Speed Controller for Ac Wound Rotor Motors

Synchronous Motor Operation

Push-Button Synchronizing

Timed Semiautomatic Synchronizing

Synchronous Automatic Motor Starter

About Dc Motors

Use of Reduced Voltage for Starting

Across-The-Line Starting

Compensating and Definite Time Control Starting

Solid-State Adjustable Speed Control

Plugging

Electric Brakes

Dynamic and Regenerative Braking

Electric and Electronic Braking

Direct Drives and Pulley Drives

Gear Motors

Variable-Frequency Mechanical Drives

Magnetic Clutch and Magnetic Drive

Dc Variable-Speed Control 14motor Drives

Programmable and Motion Control

Motor Startup and Troubleshooting Basics

Troubleshooting Techniques

Filters