True/False
Indicate whether the
statement is true or false.
|
|
|
1.
|
Changing frequency causes a corresponding change in the inductive reactance of
the windings.
|
|
|
2.
|
Alternators are often used to control the speed of several induction motors that
require different changes in speed.
|
|
|
3.
|
The Insulated Gate Bipolar Transistor (IGBT) is a current controlled device, not
a voltage controlled device.
|
|
|
4.
|
Inverter rated motors are specifically designed to be operated by variable
frequency drives.
|
|
|
5.
|
Ramping permits the motor to bring the load up to speed slowly as opposed to
simply connecting the motor directly to the line.
|
Completion
Complete each
statement.
|
|
|
6.
|
The output frequency of the alternator is determined by the speed of the
____________________.
|
|
|
7.
|
Variable frequency drives intended to control the speed of motors up to
500 hp generally use ____________________.
|
|
|
8.
|
When bipolar junction transistors are employed as switches, they are generally
driven into ____________________ by supplying them with an excessive amount of base-emitter
current.
|
|
|
9.
|
Many transistor controlled variable frequency drives now employ a special type
of transistor called a(n) ______________________________.
|
|
|
10.
|
Drives using Insulated Gate Bipolar Transistors (IGBTs) generally used
____________________ to rectify the AC voltage into DC.
|
Short Answer
|
|
|
11.
|
How can the speed on a three phase induction motor be controlled?
|
|
|
12.
|
What are two basic methods of achieving variable frequency?
|
|
|
13.
|
How do most variable frequency drives operate?
|
|
|
14.
|
What is an advantage of using Insulated Gate Bipolar Transistors (IGBTs) for
drives?
|
|
|
15.
|
What are thyristors?
|