Chapter 3 Flashcards

Theory

1
Q

What is a transformer in its simplest form referred to as?

A

Nothing more than two coils of wire placed very close to each other (but not touching)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What happens if you place the two coils of wire around an iron core?

A

Induction will be maximized, and higher voltages will be obtained

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What happens to a coil of wire that is placed next to another coil of wire that is attached to a source of AC Power?

A

It will become energized

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How can the amount of induced voltage be transformed?

A

By changing the number of turns in the secondary coil.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What do transformers directly out of the generating station do?

A

Step-Up Voltage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What do transformers located at distribution substations and on distribution poles?

A

Step-Down Voltage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is turns ratio?

A

A comparison of the number of turns of wire in each coil.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How is the turns ratio calculated?

A

By dividing the primary voltage rating by the secondary voltage rating

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is polarity?

A

The direction flow through the two coils.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Where is polarity set?

A

During the manufacturing process and cannot be changed in the field.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How is polarity determined?

A

By the direction the secondary coil is wrapped in relation to the direction the primary coil is wrapped

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What can the polarity of a transformer be?

A

Additive or Subtractive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

If it is additive, what side will the X1 Bushing be on?

A

Right-Hand Side

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

If it is subtractive, what side will the X1 Bushing be on?

A

Left-Hand Side

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is very important to know when banking and paralleling transformers?

A

Polarity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

By industry standards, what will transformers 200kVA and smaller, with a primary rating of 8660 volts and below be rated?

17
Q

What will all other transformers be rated?

A

Subtractive

18
Q

What are the two main losses of the transformer?

A

Iron and Copper Losses

19
Q

What is an Iron Loss known as?

A

No-Load Loss and they’re created by the oscillation of the magnetic field in respect to the core

20
Q

What is a Copper Loss known as?

A

Load Loss caused when a current flows in a conductor

21
Q

What does heat limit?

A

Current flow and is referred to as I2R loss

22
Q

If a transformer didn’t have these two losses how efficient would it be?

A

100% Efficient

23
Q

What is impedance?

A

Total opposition to current flow caused by the transformer

24
Q

What is impedance made up of?

A

Resistance and Inductive Reactance

25
Why is impedance important to lineworkers?
When transformers are to be banked or paralleled
26
What must transformers impedance be within to bank or parallel them?
+/- 10% of each other