True/False
Indicate whether the
statement is true or false.
|
|
|
1.
|
A step-up transformer has more turns in its secondary winding than in its
primary winding.
|
|
|
2.
|
The turns ratio for a step-up transformer is always greater than 1.
|
|
|
3.
|
The turns ratio of a step-down transformer is always less than 1.
|
|
|
4.
|
Transformers are reliable devices when operated within their specified
range.
|
Completion
Complete each
statement.
|
|
|
5.
|
When two coils are placed close to each other, a changing ____________ field
produced by the current in one coil will cause an induced voltage in the second coil because of the
mutaul inductance between the two coils.
|
|
|
6.
|
When two coils are magnetically coupled, they provide electrical __________
because there is no electrical connection between them, only magnetic link.
|
|
|
7.
|
The amount of voltage induced in the second coil as a result of the current in
the first coil is dependent on the mutual ____________, Lm.
|
|
|
8.
|
The coefficient of coupling, k, depends on the physical __________ of the coils
and the type of core material on which they are wound.
|
|
|
9.
|
A transformer is an electrical device constructed of two or more coils of wire
electromagnetically coupled to each other so that there is a mutual inductance for the transfer of
_________ from one winding to the other.
|
|
|
10.
|
One coil is called the primary winding and the other coil is called the
___________ winding.
|
|
|
11.
|
The windings of a transformer are formed around the _________.
|
|
|
12.
|
Iron-core transformers generally are used for __________ frequency and power
applications.
|
|
|
13.
|
The amount of magnetic coupling between the primary winding and the secondary
winding is set by the type of _________ material and by the relative positions of the
windings.
|
|
|
14.
|
A transformer parameter that is useful in understanding how a transformer
operates is the ________ ratio.
|
|
|
15.
|
Another important transformer parameter is the _________ in which the windings
are placed around the core.
|
|
|
16.
|
A transformer in which the secondary voltage is greater than the primary voltage
is called a __________ transformer.
|
|
|
17.
|
A transformer in which the secondary voltage is less than the primary voltage is
called a ___________ transformer.
|
|
|
18.
|
A transformer that is used strictly for _________ has a turns ratio of 1.
|
|
|
19.
|
Coupling transformers are also used for audio frequencies, but primarily to
couple a signal from an __________ to a speaker.
|
|
|
20.
|
If a transformer is operated with no load, the primary acts like an
___________.
|
|
|
21.
|
In ac circuits, the total opposition to current is referred to as impedance and
the term ____________ matching is used to show that the source and load impedances are equal.
|
|
|
22.
|
A special type of transformer called a __________ is used to convert the
unbalanced signal from the transmitter to a balanced signal at the antenna.
|
|
|
23.
|
The center tap is equivalent to two secondary windings with half the total
___________ across each.
|
|
|
24.
|
Utility companies use many tapped _________________ in distribution
systems.
|
|
|
25.
|
Applications of the ______________ include starting industrial induction motors
and regulating transmission line voltages.
|
|
|
26.
|
Three-phase power is generally not used in ____________ applications.
|
|
|
27.
|
Normally, when a transformer fails, it is very difficult to repair, and
therefore the simplest procedure is to ______ it.
|
|
|
28.
|
When there is an open secondary winding, there is no _________ in the secondary
circuit and, as a result, no voltage load across it.
|
|
|
29.
|
A completely shorted primary winding will draw excessive ________ from the
source.
|