Chapter 2

Question 1

Internally, what are the 3 main components that make up a Transformer?

Answer 1

The core, the windings and the insulating fluid

Question 2

What else are Transformers equipped with?

Answer 2

Pressure relief valves

Question 3

What are CSP Transformer equipped with internally?

Answer 3

Fuses

Question 4

What does the core of a transformer provide?

Answer 4

A path for magnetic coupling of the two windings

Question 5

What does the core concentrate?

Answer 5

The magnet flux lines, which substantially improves effeciency

Question 6

What is the core made of?

Answer 6

Thin laminations of gran-oriented silicon steel rolled into layers, with each side coated with an insulating material.

Question 7

What does the core have a significant impact on?

Answer 7

The wat losses of the transformer

Question 8

What are the two configurations of a Transformer’s Core?

Answer 8

• Wound Type Core

- Shell Type Core

Question 9

What does the core type for distribution transformers depend upon?

Answer 9

Manufacturer and the type of transformer

Question 10

What is the type of steel that’s been recently utilized?

Answer 10

Amorphous Steel

Question 11

Why is Amorphous Steel utilized?

Answer 11

To further reduce the losses within the core

Question 12

What is the most popular material for the windings?

Answer 12

Copper

Question 13

Why is Copper the most popular used material?

Answer 13

Low resistance and superb conductivity

Question 14

Which typically has smaller sized wire used for the windings the primary or secondary windings?

Answer 14

Primary Windings

Question 15

What shape might the winding wire take?

Answer 15

Either round or in rectangular ribbon form

Question 16

What are the winding conductors coated with?

Answer 16

Insulation to to prevent the turns from shorting out

Question 17

Where are the ends of the windings attached?

Answer 17

To the primary and secondary terminals

Question 18

What are the secondary winding ends tagged with?

Answer 18

A-B-C-D

Question 19

Where are the ends of the windings brought out from when attaching them to the primary and secondary terminals?

Answer 19

Brought out of the core and coil assembly

Question 20

What is the role of the Insulating fluid?

Answer 20

Cooling and insulating the core and coil assembly

Question 21

How does it facilitate the cooling process?

Answer 21

By transferring the heat generated in the coil and core assembly to the tank or radiators, where it will be dissipated to the outside atmosphere

Question 22

What happens as the core heats?

Answer 22

The oil rises.

Question 23

What happens when the oil rises?

Answer 23

It’s forced against the case of the transformer where it radiates heat into the atmosphere and cools.

Question 24

What happens when the oil cools?

Answer 24

It circulates down to the bottom of the core.

Question 25

What is convection?

Answer 25

The circulation of the oil by heat

Question 26

What is the insulating fluid?

Answer 26

Mineral oil

Question 27

What is important to understand about Mineral oil?

Answer 27

It's flammable under certain conditions

Question 28

What does PCB stand for?

Answer 28

Polychlorinated Biphenyls

Question 29

What is askarel?

Answer 29

The term PCB relates to a substance that can be a part of an insulating fluid.

Question 30

What has PCB been determined as?

Answer 30

To be harmful to the environment and is prohibited in new transformers.

Question 31

What is important to know when working on older transformers?

Answer 31

Be alert to the type of insulating fluid

Question 32

What is the insulated fluid indicated by?

Answer 32

A non-PCB stag or sticker, or by the data on the nameplate

Question 33

What can build up inside a transformer?

Answer 33

Pressure in the form of gas can build up inside

Question 34

Why would pressure build up inside?

Answer 34

Short in the windings, which breaks down the impurities in the oil creating gas

Question 35

What can this pressure do?

Answer 35

Build up and blow off the lid

Question 36

What do manufacturer's now include to alleviate this potential?

Answer 36

A valve located just above the oil level, which allows internal pressure to escape to the atmosphere

Question 37

What does the valve do?

Answer 37

The valve will vent when the internal pressure reaches approx. 10lbs/sq inch.

Question 38

What is normally added when older transformers are built?

Answer 38

Pressure Relief Valve

Question 39

What do the internal fuses in CSP Transformers do?

Answer 39

Isolate and protect the transformer from internal faults.

Question 40

What must be done to replace this fuse?

Answer 40

The transformer must be de-energized and the lid removed

Question 41

What else does a CSP Transformer have?

Answer 41

An Internal Secondary Breaker

Question 42

What does the internal secondary breaker do?

Answer 42

Disconnect the hot legs in the event of an overload or a short circuit on the secondary side

Question 43

Where are the Pad-Mounted Transformers fuses?

Answer 43

Internal, but operated externally, located in the primary compartment and are under the oil level