CEA Transformers and Distribution Systems

Question 1

What is the turns ratio of a transformer with a primary winding of 480 turns and a secondary winding of 120 turns?

Accepted Answer

4:1

Answer

1:4

Answer

2:1

Answer

1:2

Question 2

A step-down transformer has a 2:1 turns ratio and a primary voltage of 240V. What is the secondary voltage?

Accepted Answer

120V

Answer

480V

Answer

240V

Answer

60V

Question 3

What operating principle allows a transformer to transfer electrical energy between two circuits?

Accepted Answer

Mutual electromagnetic induction

Answer

Electrostatic induction

Answer

Direct current amplification

Answer

Resistance heating

Question 4

Which transformer type has its secondary winding electrically isolated from the primary winding with no common connection?

Accepted Answer

Isolation transformer

Answer

Autotransformer

Answer

Current transformer

Answer

Potential transformer

Question 5

If an ideal transformer draws 5A at 240V on the primary, what is the secondary current when the secondary voltage is 120V?

Accepted Answer

10A

Answer

5A

Answer

2.5A

Answer

20A

Question 6

What core material is most commonly used in power transformers to reduce eddy current losses?

Accepted Answer

Silicon steel laminations

Answer

Solid copper

Answer

Solid aluminum

Answer

Ferrite powder

Question 7

A transformer nameplate shows a KVA rating of 75 KVA. What does this rating represent?

Accepted Answer

The apparent power capacity in kilovolt-amperes the transformer can handle continuously

Answer

The maximum kilowatts of real power the transformer can deliver

Answer

The transformer's efficiency at full load

Answer

The primary voltage multiplied by secondary current in amperes