Principles of Star and Delta

Question 1

Question

Which of the above values shows the line voltage for a star connected load

Image:

Answer

Question 2

Question

Which of the following values would be the approximate value of line voltage for a delta connected load with a phase voltage of 900V

Answer

600V
519.6 V
1.56 kV
900V

Question 3

Question

A three phase delta connected load has a phase voltage of 230V what would be the approximate line voltage

Answer

230 V
400 V
133 V
240 V

Question 4

Question

In a star connected system what is the relationship between the line and phase voltage

Answer

V PHASE = V LINE x 1.732
V LINE = V PHASE x √3
V LINE = V PHASE/√3
V LINE = V PHASE

Question 5

Question

Which of the following values would be the approximate value of phase voltage for a delta connected load with a line voltage of 400V

Answer

693.2 V
231.2 V
400 V
692.8 V

Question 6

Question

Which of the above values shows the line current for a delta connected load

Image:

Slide2.JPG (image/JPG)

Answer

Question 7

Question

Which of the following values would be the approximate value of line current for a delta connected load with a phase current of 75A

Answer

34.7 A
60 A
129.90 A
104 A

Question 8

Question

Which of the following values would be the approximate value of line current for a delta connected load with a phase current of 60A

Answer

34.7 A
103.92 A
130 A
60.21 A

Question 9

Question

Which of the below values shows the phase voltage for a star connected load

Image:

Slide1.JPG (image/JPG)

Answer

Question 10

Question

Which of the above values shows the phase current for a delta connected load

Image:

Slide2.JPG (image/JPG)

Answer

Question 11

Question

Why is it important to balance three phase loads as evenly as possible across the three phases

Answer

to reduce the neutral current
to improve the power factor
to reduce the voltage
to reduce disconnection times

Question 12

Question

Which of the following would not require a neutral connection

Answer

single phase load
three phase unbalanced loads
three phase balanced loads
T.T system

Question 13

Question

Which of the following values is the approximate neutral current for a balanced star connected load drawing 12 A per phase

Answer

20.78 A
36 A
0 A
12 A

Question 14

Question

Which of the following values would be the approximate value of line current for a star connected load with a phase current of 110 A

Answer

75 A
110 A
43.3 A
130 A

Question 15

Question

Which of the following values would be the approximate value of phase current for a star connected load with a line current of 90 A

Answer

155.9 A
90 A
51.96 A
30 A

Question 16

Question

Which of the above meters shows the line voltage for a star connected load

Image:

Slide1.JPG (image/JPG)

Answer

Question 17

Question

Which of the above meters shows the phase voltage for a star connected load

Image:

Slide1.JPG (image/JPG)

Answer

Question 18

Question

Which of the above meters shows the phase current for a star connected load

Image:

Slide1.JPG (image/JPG)

Answer

1
none of the above
2
3

Question 19

Question

What is the approximate value of line current for the delta system shown?

Image:

Slide2.JPG (image/JPG)

Answer

20A
6.7A
11.5A
34.6A

Question 20

Question

What is the approximate value of phase current for the delta system shown?

Image:

Slide4.JPG (image/JPG)

Answer

34.6A
6.7A
11.5A
20A

Question 21

Question

Which of the following is the phase voltage for the star system shown

Image:

Slide3.JPG (image/JPG)

Answer

60V
11.55V
34.64V
20V

Question 22

Question

What is the approximate value of phase voltage for the delta system shown

Image:

Slide4.JPG (image/JPG)

Answer

87V
230V
260V
150V

Question 23

Question

What is the approximate value of phase current for the delta system shown?

Image:

Slide5.JPG (image/JPG)

Answer

20A
6.71A
11.54A
34.6A

Question 24

Question

What formula would you use to calculate the Line voltage

Answer

VLINE = 230 + √3
VLINE = 230/√3
VLINE = 230
VLINE = √3 x 230

Question 25

Question

Three phase Star connected system provided with a neutral can be used for

Answer

The connection of three phase loads
The connection of delta loads
The connection of an earth
The connection of single phase loads

Question 26

Question

In a star connected system what is the relationship between the line and phase current

Answer

I LINE = I PHASE /√3
V = I x R
I LINE = I PHASE x 1.732
I LINE = I PHASE

Question 27

Question

From the following diagram what number represents the Line Current

Image:

Slide6.JPG (image/JPG)

Answer

Question 28

Question

From the following diagram if number 1 is 11kV what would the value number 3 be

Image:

Slide6.JPG (image/JPG)

Answer

19kV
6.35kA
6.35kV
11kV

Question 29

Question

From the diagram below, what does the number 4 represent

Image:

Slide6.JPG (image/JPG)

Answer

Phase Voltage
Phase Current
Line Voltage
Line Current

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Principles of Star and Delta

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Resource summary

Question 1

Question 2

Question 3

Question 4

Question 5

Question 6

Question 7

Question 8

Question 9

Question 10

Question 11

Question 12

Question 13

Question 14

Question 15

Question 16

Question 17

Question 18

Question 19

Question 20

Question 21

Question 22

Question 23

Question 24

Question 25

Question 26

Question 27

Question 28

Question 29

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	Created by Vito Martino almost 10 years ago