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Flashcards in Power Distribution Deck (15)
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1

For residential areas, substations reduce the voltage from 120,000 volts down to
A. 8400 volts
B. 4800 volts
C. 5200 volts
D. 2500 volts

B. 4800 volts

2

For commercial areas, substations reduce the voltage from 120,000 volts down to
A. 34,000 volts
B. 43,000 volts
C. 52,000 volts
D. 25,000 volts

A. 34,000 volts

3

A step down transformer will reduce the voltage to a common low voltage residential application of
A. 240 volts, single phase, 60 Hz
B. 240 volts, three phase, 60 Hz
C. 480 volts, single phase, 60 Hz
D. 460 volts, three phase, 60 Hz

A. 240 volts, single phase, 60 Hz

4

Using a delta transformer, commercial applications will step the voltage down to
A. 240 volts, single phase, 60 Hz
B. 240 volts, three phase, 60 Hz
C. 480 volts, single phase, 60 Hz
D.208 volts, three phase, 60 Hz

B. 240 volts, three phase, 60 Hz

5

Using a wye transformer, commercial applications will step the voltage down to
A. 240 volts, single phase, 60 Hz
B. 240 volts, three phase, 60 Hz
C. 480 volts, single phase, 60 Hz
D. 208 volts, three phase, 60 Hz

D. 208 volts, three phase, 60 Hz

6

When measuring voltage using a voltmeter, across any two hot legs of a low voltage wye transformer should read
A. 120 volts
B. 240 volts
C. 208 volts
D. 460 volts

C. 208 volts

7

When measuring the voltage on a low voltage delta system, what reading would be obtained across any two hot legs?
A. 120 volts
B. 240 volts
C. 208 volts
D. 480 volts

B. 240 volts

8

Which three phase system, when measuring from L1, L2, and L3 to ground will read 120 volts?
A. A 120 volt, three phase delta system
B. A 208 volt, three phase delta system
C. A 480 volt, three phase wye system
D. A 208 volt, three phase wye system

D. A 208 volt, three phase wye system

9

Which three phase electrical system will measure 120 volts when testing two of the hot leads to ground and 208 volts on the third hot leg to ground?
A. 460 volt, three phase delta system
B. A 240 volt, three phase delta system
C. A 480 volt, three phase wye system
D. A 208 volt, three phase wye system

B. A 240 volt, three phase delta system

10

On a wye transformer, what voltage reading should be from L1 to L2?
A. 240 volts
B. 120 volts
C. 208 volts
D. 277 volts

C. 208 volts

11

On a wye transformer, what voltage reading should be from L1 to ground?
A. 240 volts
B. 120 volts
C. 208 volts
D. 480 volts

B. 120 volts

12

On the delta transformer, what voltage reading should be from L1 to L2?
A. 240 volts
B. 120 volts
C. 208 volts
D. 277 volts

A. 240 volts

13

On the delta transformer, what voltage reading should be from L1 to ground?
A. 240 volts
B. 120 volts
C. 208 volts
D. 480 volts

C. 208 volts

14

When placing a voltmeter across any two legs on a 480 volt three phase system, what voltage reading should be obtained?
A. 240 volts
B. 208 volts
C. 480 volts
D. 277 volts

C. 480 volts

15

What is the maximum voltage output of a 240 volt single phase power supply?
A. 250 volts
B. 240 volts
C. 277 volts
D. 264 volts

D. 264 volts