Final Review

Question 1

What article of the NEC relates to transformers?

A. 250
B. 430
C. 450
D. 500

Answer 1

C. 450

Question 2

What is the main function of a transformer?

A. Convert electrical energy to mechanical energy
B. Step-up or step-down voltage
C. Generate electricity
D. control current flow

Answer 2

B. Step-up or step-down voltage

Question 3

What is the purpose of the taps in a transformer?

A. Change output current
B. Change output voltage
C. Serve as a ground
D. None of the above

Answer 3

B. Change output voltage

Question 4

The core of a transformer is made of which material to reduce energy loss?

A. Copper
B. Plastic
C. Iron or steel
D. Aluminum

Answer 4

C. Iron or steel

Question 5

What happens to current on the secondary side when voltage is stepped-down?

A. Increases
B. Decreases
C. Stays the same
D. Goes to zero

Answer 5

A. Increases

Question 6

The purpose of transformer oil is to

A. Reduce core losses
B. Provide insulation and cooling
C. Step-down voltage
D. Increase efficiency

Answer 6

B. Provide insulation and cooling

Question 7

Which of the following is a type of transformer used in 3-phase electrical systems?

A. Delta-Delta
B. Delta-Wye
C. Wye-Wye
D. All of the above

Answer 7

D. All of the above

Question 8

The kVA rating defines the capacity of the transformer.

True or False

Answer 8

True

Question 9

Where does the Grounding Electrode Conductor (GEC) land in a transformer?

A. Lug on can
B. X1
C. H1
D. X0

Answer 9

D. X0

Question 10

What is the minimum clearance needed around an indoor transformer for ventilation?

A. 3 inches
B. 6 inches
C. 9 inches
D. 12 inches

Answer 10

B. 6 inches

Question 11

What is the minimum clearance needed around an outdoor transformer for ventilation?

A. 6 feet
B. 1 foot
C. 3 feet
D. 9 feet

Answer 11

C. 3 feet

Question 12

When a motor starts, what can happen to the current?

A. Nothing
B. Goes Down
C. Spikes Up
D. Drops to Zero

Answer 12

C. Spikes Up

Question 13

What type of transformer is used to provide electrical isolation between two circuits?

A. Step-up
B. Step-down
C. Isolation
D. Autotransformer

Answer 13

C. Isolation

Question 14

All two-winding transformers are isolation transformers.

True or False

Answer 14

True

Question 15

What are the functions of a reactor?

A. Current limitation
B. Harmonic filtering
C. Voltage stabilization
D. All of the above

Answer 15

D. All of the above

Question 16

What is the range of a buck-boost transformer?

A. 5-10%
B. 10-15%
C. 10-20%
D. 15-25%

Answer 16

C. 10-20%

Question 17

A device designed to protect electrical equipment from high-voltage surges, such as those caused by lightning or switching events in a power system defines what?

A. Arrester
B. Isolator
C. Bushing
D. Core

Answer 17

A. Arrester

Question 18

Calculate the amount of amps on a 15 kVA, 3phase, 480-volt transformer.

Answer 18

18.06 A

(15 x 1000) ÷ (480 x 1.73) = 18.0636

Question 19

Using the answer from question 18, calculate the maximum OCPD permitted on the primary side of a 15 kVA, 3 phase, 480-volt transformer.

A. 20 amp
B. 25 amp
C. 30 amp
D. 40 amp

Answer 19

B. 25 amp

Question 20

Who is responsible for your safety?

A. Foreman
B. Journeyman
C. GC
D. You

Answer 20

D. You