G.PULLAIAH COLLEGE OF ENGINEERING & TECHNOLOGY (AT)

II.B.Tech, II- Sem. Objective – MID TERM-I Exam SET-1 Branch: EEE(A & B Sections)

Sub: ELECTRICAL MACHINES-II Date: 03/03/2018

Time: 20 min Max.Marks:10

Regd.No…………………………………….

================================================================

Note: Answer the ALL Questions. 1. Transformer core is made of

(a) Silicon sheet steel (b) chromium steel (c) low carbon steel (d) stainless steel( )

2. Open circuit test on a transformer is conducted to obtain ( )

(a) The leakage impedances (b) The ohmic loss(c) Hysteresis loss only (d) Core loss

3. Transformer action requires a ( )

(a) Constant magnetic flux (b) Increasing magnetic flux

(c) Alternating magnetic flux (d) Alternating electric flux.

4. The voltage regulation of transformer not depends on the following parameters ( )

(a) Resistance (b) Reactance (c) Power factor (d) Losses.

5. Power input to a transformer on no load at rated voltage comprises predominantly ( )

(a) Copper loss (b) Hysteresis loss (c) Core loss (d) Eddy current loss.

6. The oil selected for transformer cooling should be free from ( )

(a) Alkalies (b) Acids (c) Sulphur (d) All of the above.

7. The no load current of the transformer is _____ percentage of the full load current ( )

(a) 10% (b) 3% (c) 40% (d) none of the above

8. In transformer, the supply frequency is increased with constant voltage then the eddy current

losses and hysteresis losses are respectively ( )

(a) Increases, decreases (b) constant, decreases

(c) decreases, constant (d) decreases,increases

9. The cu and iron losses are 80 w and 50w respectively, at full load, and then the cu loss and

iron loss are ___ at ¼ of the full load respectively, are ( )

(a) 10w, 15w (b) 80w, 2.6w (c) 5W, 50w (d) 50w, 205w

10. The flux which has low reluctance path has ф, at full load, then at half load the flux will be

(a) Doubled (b) half (c) Remain constant (d) None ( )

11. The efficiency of the auto transformer is_____ than the ordinary transformers

(a) Higher (b) Lower (c) Equal (d) None ( )

12. Two transformers are operating in parallel; their load sharing will depend upon( )

(a) Cooling methods (b) all day efficiency (c) max efficiency (d) per unit impedance

G.PULLAIAH COLLEGE OF ENGINEERING & TECHNOLOGY (AT)

II.B.Tech, II- Sem. Objective – MID TERM-I Exam SET-1 Branch: EEE(A & B Sections)

Sub: ELECTRICAL MACHINES-II Date: 03/03/2018

Time: 20 min Max.Marks:10

Regd.No…………………………………….

================================================================

Note: Answer the ALL Questions. 1. Transformer core is made of

(a) Silicon sheet steel (b) chromium steel (c) low carbon steel (d) stainless steel( )

2. Open circuit test on a transformer is conducted to obtain ( )

(a) The leakage impedances (b) The ohmic loss(c) Hysteresis loss only (d) Core loss

3. Transformer action requires a ( )

(a) Constant magnetic flux (b) Increasing magnetic flux

(c) Alternating magnetic flux (d) Alternating electric flux.

4. The voltage regulation of transformer not depends on the following parameters ( )

(a) Resistance (b) Reactance (c) Power factor (d) Losses

5. Power input to a transformer on no load at rated voltage comprises predominantly ( )

(a) Copper loss (b) Hysteresis loss (c) Core loss (d) Eddy current loss.

6. The oil selected for transformer cooling should be free from ( )

(a) Alkalies (b) Acids (c) Sulphur (d) All of the above.

7. The no load current of the transformer is _____ percentage of the full load current ( )

(a) 10% (b) 3% (c) 40% (d) none of the above

8. In transformer, the supply frequency is increased with constant voltage then the eddy current

losses and hysteresis losses are respectively ( )

(a) Increases, decreases (b) constant, decreases

c) decreases, constant (d) decreases,increases

9. The cu and iron losses are 80 w and 50w respectively, at full load, and then the cu loss and

iron loss are ___ at ¼ of the full load respectively, are

(a) 10w, 15w (b) 80w, 2.6w (c) 5W, 50w (d) 50w, 205w ( )

10. The flux which has low reluctance path has ф, at full load, then at half load the flux will be

(a) Doubled (b) half (c) Remain constant (d) None ( )

11. The efficiency of the auto transformer is_____ than the ordinary transformers

(a) Higher (b) Lower (c) Equal (d) None ( )

12. Two transformers are operating in parallel; their load sharing will depend upon ( )

(a) Cooling methods (b) all day efficiency (c) max efficiency (d) per unit impedance

13. Short circuit test on a transformer can be used to determine ( )

(a) Cu loss (b) iron loss (c) regulation (d) Equivalent resistance & reactance

14. At 50 Hz operation, a single phase transformer has hysteresis loss of 200W and eddy current

loss of 100W, its core loss at 60 Hz operation will be ( )

(a) 432W (B) 408W (C) 384W (D) 360W

15. Scott connections are used for

(a) 1-ф to 3-ф transformation (b) 3-ф to 1-ф transformation ( )

(c) 3-ф to 2-ф transformation (d) none

16. In two parallel connected transformers, if the ratio of Xa/Ra > Xb/Rb, then transformer A

and transformer B are operates at a

(a) More p.f & poor p.f respectively (b) poor p.f & More p.f respectively ( )

(c) Both are operates More p.f s (d) Both are operates poor p.fs

17. What is the advantage of three single phase transformers over the single three phase

transformer?

Ans:

18. Which of the following connections is best suited for 3-phase, 4-wire service?

(a) delta-delta (b) star-star (c) delta-star (d) star-delta ( )

19. In a three phase Y-Y transformer connection, neutral is fundamental to the ( )

(a) Suppression of harmonics (b) passage of unbalanced currents due to unbalanced loads

(c) Provision of dual electric service (d) None

20. A 200KVA transformer has an iron loss of 1 KW and full load cu loss of 2 KW. Its load

KVA corresponding to maximum efficiency is ______KVA. ( )

(a) 100 (b) 141.4 (c) 50 (d) 200

Signature of the Faulty Signature of the HOD

13. Short circuit test on a transformer can be used to determine ( )

(a) Cu loss (b) iron loss (c) regulation (d) Equivalent resistance & reactance

14. At 50 Hz operation, a single phase transformer has hysteresis loss of 200W and eddy current

loss of 100W, its core loss at 60 Hz operation will be ( )

(a) 432W (B) 408W (C) 384W (D) 360W

15. In two parallel connected transformers, if the ratio of Xa/Ra > Xb/Rb, then transformer A

and transformer B are operates at a

(a) More p.f & poor p.f respectively (b) poor p.f & More p.f respectively ( )

(c) Both are operates More p.f s (d) Both are operates poor p.fs

16. Scott connections are used for

(a) 1-ф to 3-ф transformation (b) 3-ф to 1-ф transformation ( )

(c) 3-ф to 2-ф transformation (d) none

17. What is the advantage of three single phase transformers over the single three phase

transformer?

Ans:

18. Which of the following connections is best suited for 3-phase, 4-wire service?

(a) delta-delta (b) star-star (c) delta-star (d) star-delta ( )

19. In a three phase Y-Y transformer connection, neutral is fundamental to the ( )

(a) Suppression of harmonics (b) passage of unbalanced currents due to unbalanced loads

(c) Provision of dual electric service (d) None

20. A 200KVA transformer has an iron loss of 1 KW and full load cu loss of 2 KW. Its load

KVA corresponding to maximum efficiency is ______KVA. ( )

(a) 100 (b) 141.4 (c) 50 (d) 200

Signature of the Faulty Signature of the HOD

G.PULLAIAH COLLEGE OF ENGINEERING & TECHNOLOGY (AT)

II.B.Tech, II- Sem. Objective – MID TERM-I Exam SET-2

Branch: EEE

Sub: ELECTRICAL MACHINES-II Date: 03 /03/2018

Time: 20 min Max.Marks:10

Regd.No…………………………………….

================================================================

Note: Answer the ALL Questions.

1. The efficiency of an auto transformer is_____ than the ordinary transformers

(a) Higher (b) Lower (c) Equal (d) None ( )

2. Two transformers are operating in parallel; their load sharing will depend upon ( )

(a) Cooling methods (b) all day efficiency (c) max efficiency (d) per unit impedance

3. Short circuit test on a transformer can be used to determine ( )

(a) Cu loss (b) iron loss (c) regulation (d) Equivalent resistance & reactance

4. At 50 Hz operation, a single phase transformer has hysteresis loss of 200W and eddy current

loss of 100W, its core loss at 60 Hz operation will be ( )

(a) 432W (B) 408W (C) 384W (D) 360W

5. In two parallel connected transformers, if the ratio of Xa/Ra > Xb/Rb, then transformer A and

transformer B are operates at a

(a) More p.f & poor p.f respectively (b) poor p.f & More p.f respectively ( )

(c) Both are operates More p.f s (d) Both are operates poor p.fs

6. The oil selected for transformer cooling should be free from ( )

(a) Alkalies (b) Acids (c) Sulphur (d) All of the above.

7. The no load current of the transformer is _____ percentage of the full load current ( )

(a) 10% (b) 3% (c) 40% (d) none of the above

8. In transformer, the supply frequency is increased with constant voltage then the eddy current

losses and hysteresis losses are respectively ( )

(a) Increases, decreases (b) constant, decreases

(c) Decreases, constant (d) decreases, increases

9. The cu and iron losses are 80 w and 50w respectively, at full load, and then the cu loss and

iron loss are ___ at ¼ of the full load respectively, are ( )

(a) 10w, 15w (b) 80w, 2.6w (c) 5W, 50w (d) 50w, 205w

10. The flux which has low reluctance path has ф, at full load, then at half load the flux will be

(a) Doubled (b) half (c) Remain constant (d) None ( )

11. Scott connections are used for

(a) 1-ф to 3-ф transformation (b) 3-ф to 1-ф transformation ( )

(c) 3-ф to 2-ф transformation (d) none

G.PULLAIAH COLLEGE OF ENGINEERING & TECHNOLOGY (AT)

II.B.Tech, II- Sem. Objective – MID TERM-I Exam SET-2

Branch: EEE(A & B Sections)

Sub: ELECTRICAL MACHINES-II Date: 03 /03/2018

Time: 20 min Max.Marks:10

Regd.No…………………………………….

================================================================

Note: Answer the ALL Questions.

1. The efficiency of the auto transformer is_____ than the ordinary transformers

(a) Higher (b) Lower (c) Equal (d) None ( )

2. Two transformers are operating in parallel; their load sharing will depend upon ( )

(a) Cooling methods (b) all day efficiency (c) max efficiency (d) per unit impedance

3. Short circuit test on a transformer can be used to determine ( )

(a) Cu loss (b) iron loss (c) regulation (d) Equivalent resistance & reactance

4. At 50 Hz operation, a single phase transformer has hysteresis loss of 200W and eddy current

loss of 100W, its core loss at 60 Hz operation will be ( )

(a) 432W (B) 408W (C) 384W (D) 360W

5. In two parallel connected transformers, if the ratio of Xa/Ra > Xb/Rb, then transformer A and

transformer B are operates at a

(a) More p.f & poor p.f respectively (b) poor p.f & More p.f respectively ( )

(c) Both are operates More p.f s (d) Both are operates poor p.fs

6. The oil selected for transformer cooling should be free from ( )

(a) Alkalies (b) Acids (c) Sulphur (d) All of the above.

7. The no load current of the transformer is _____ percentage of the full load current ( )

(a) 10% (b) 3% (c) 40% (d) none of the above

8. In transformer, the supply frequency is increased with constant voltage then the eddy current

losses and hysteresis losses are respectively ( )

(a) Increases, decreases (b) constant, decreases

(c) Decreases, constant (d) decreases, increases

9. The cu and iron losses are 80 w and 50w respectively, at full load, and then the cu loss and

iron loss are ___ at ¼ of the full load respectively, are ( )

(a) 10w, 15w (b) 80w, 2.6w (c) 5W, 50w (d) 50w, 205w

10. The flux which has low reluctance path has ф, at full load, then at half load the flux will be

(a) Doubled (b) half (c) Remain constant (d) None ( )

11. Scott connections are used for

(a) 1-ф to 3-ф transformation (b) 3-ф to 1-ф transformation ( )

(c) 3-ф to 2-ф transformation (d) none

12. What is the advantage of three single phase transformer over the single three phase

transformer?

Ans:

13. Which of the following connections is best suited for 3-phase, 4-wire service?

(a) delta-delta (b) star-star (c) delta-star (d) star-delta ( )

14. In a three phase Y-Y transformer connection, neutral is fundamental to the ( )

(a) Suppression of harmonics (b) passage of unbalanced currents due to unbalanced loads

(c) Provision of dual electric service (d) None

15. A 200KVA transformer has an iron loss of 1 KW and full load cu loss of 2 KW. Its load

KVA corresponding to maximum efficiency is ______KVA. ( )

(a) 100 (b) 141.4 (c) 50 (d) 200

16. Transformer core is made of

(a) Silicon sheet steel (b) chromium steel (c) low carbon steel (d) stainless steel ( )

17. Open circuit test on a transformer is conducted to obtain ( )

(a) The leakage impedances (b) The ohmic loss (c) Hysteresis loss only (d) Core loss

18. Transformer action requires a ( )

(a) Constant magnetic flux (b) Increasing magnetic flux

(c) Alternating magnetic flux (d) Alternating electric flux.

19. The voltage regulation of transformer not depends on the following parameters ( )

(a) Resistance (b) Reactance (c) Power factor (d) Losses.

20. Power input to a transformer on no load at rated voltage comprises predominantly ( )

(a) copper loss (b) hysteresis loss (c) core loss (d) eddy current loss.

Signature of the Faulty Signature of the HOD

12. What is the advantage of three single phase transformers over the single three phase

transformer?

Ans:

13. Which of the following connections is best suited for 3-phase, 4-wire service?

(a) delta-delta (b) star-star (c) delta-star (d) star-delta ( )

14. In a three phase Y-Y transformer connection, neutral is fundamental to the ( )

(a) Suppression of harmonics (b) passage of unbalanced currents due to unbalanced loads

(c) Provision of dual electric service (d) None

15. A 200KVA transformer has an iron loss of 1 KW and full load cu loss of 2 KW. Its load

KVA corresponding to maximum efficiency is ______KVA. ( )

(a) 100 (b) 141.4 (c) 50 (d) 200

16. Transformer core is made of

(a) Silicon sheet steel (b) chromium steel (c) low carbon steel (d) stainless steel ( )

17. Open circuit test on a transformer is conducted to obtain ( )

(a) The leakage impedances (b) The ohmic loss (c) Hysteresis loss only (d) Core loss

18. Transformer action requires a ( )

(a) Constant magnetic flux (b) Increasing magnetic flux

(c) Alternating magnetic flux (d) Alternating electric flux.

19. The voltage regulation of transformer not depends on the following parameters ( )

(a) Resistance (b) Reactance (c) Power factor (d) Losses

20. Power input to a transformer on no load at rated voltage comprises predominantly ( )

(a) Copper loss (b) hysteresis loss (c) core loss (d) eddy current loss.

Signature of the Faulty Signature of the HOD

G.PULLAIAH COLLEGE OF ENGINEERING & TECHNOLOGY (AT)

II.B.Tech, II- Sem. Objective – MID TERM-I Exam SET-3

Branch: EEE(A & B Sections)

Sub: ELECTRICAL MACHINES-II Date: 03/03/2018

Time: 20 min Max.Marks:10

Regd.No…………………………………….

================================================================

Note: Answer the ALL Questions.

1. Scott connections are used for

(a) 1-ф to 3-ф transformation (b) 3-ф to 1-ф transformation ( )

(c) 3-ф to 2-ф transformation (d) none

2. What is the advantage of three single phase transformers over the single three phase

transformer?

Ans:

3. Which of the following connections is best suited for 3-phase, 4-wire service?

(a) delta-delta (b) star-star (c) delta-star (d) star-delta ( )

4. In a three phase Y-Y transformer connection, neutral is fundamental to the ( )

(a) Suppression of harmonics (b) passage of unbalanced currents due to unbalanced loads

(c) Provision of dual electric service (d) None

5. A 200KVA transformer has an iron loss of 1 KW and full load cu loss of 2 KW. Its load KVA

corresponding to maximum efficiency is ______KVA. ( )

(a) 100 (b) 141.4 (c) 50 (d) 200

6. The efficiency of the auto transformer is_____ than the ordinary transformers

(a) Higher (b) Lower (c) Equal (d) None ( )

7. Two transformers are operating in parallel; their load sharing will depend upon ( )

(a) Cooling methods (b) all day efficiency (c) max efficiency (d) per unit impedance

8. Short circuit test on a transformer can be used to determine ( )

(a) Cu loss (b) iron loss (c) regulation (d) Equivalent resistance & reactance

9. At 50 Hz operation, a single phase transformer has hysteresis loss of 200W and eddy current

loss of 100W, its core loss at 60 Hz operation will be ( )

(a) 432W (B) 408W (C) 384W (D) 360W

10. In two parallel connected transformers, if the ratio of Xa/Ra > Xb/Rb, then transformer A

and transformer B are operates at a

(a) More p.f & poor p.f respectively (b) poor p.f & More p.f respectively ( )

(c) Both are operates More p.f s (d) Both are operates poor p.fs

11. Transformer core is made of ( )

(a) Silicon sheet steel (b) chromium steel (c) low carbon steel (d) stainless teel

G.PULLAIAH COLLEGE OF ENGINEERING & TECHNOLOGY (AT)

II.B.Tech, II- Sem. Objective – MID TERM-I Exam SET-3

Branch: EEE(A & B Sections)

Sub: ELECTRICAL MACHINES-II Date: 03/03/2018

Time: 20 min Max.Marks:10

Regd.No…………………………………….

================================================================

Note: Answer the ALL Questions.

1. Scott connections are used for

(a) 1-ф to 3-ф transformation (b) 3-ф to 1-ф transformation ( )

(c) 3-ф to 2-ф transformation (d) none

2. What is the advantage of three single phase transformers over the single three phase

transformer?

Ans:

3. Which of the following connections is best suited for 3-phase, 4-wire service?

(a) delta-delta (b) star-star (c) delta-star (d) star-delta ( )

4. In a three phase Y-Y transformer connection, neutral is fundamental to the ( )

(a) Suppression of harmonics (b) passage of unbalanced currents due to unbalanced loads

(c) Provision of dual electric service (d) None

5. A 200KVA transformer has an iron loss of 1 KW and full load cu loss of 2 KW. Its load KVA

corresponding to maximum efficiency is ______KVA. ( )

(a) 100 (b) 141.4 (c) 50 (d) 200

6. The efficiency of the auto transformer is_____ than the ordinary transformers

(a) Higher (b) Lower (c) Equal (d) None ( )

7. Two transformers are operating in parallel; their load sharing will depend upon ( )

(a) Cooling methods (b) all day efficiency (c) max efficiency (d) per unit impedance

8. Short circuit test on a transformer can be used to determine ( )

(a) Cu loss (b) iron loss (c) regulation (d) Equivalent resistance & reactance

9. At 50 Hz operation, a single phase transformer has hysteresis loss of 200W and eddy current

loss of 100W, its core loss at 60 Hz operation will be ( )

(a) 432W (B) 408W (C) 384W (D) 360W

10. In two parallel connected transformers, if the ratio of Xa/Ra > Xb/Rb, then transformer A

and transformer B are operates at a

(a) More p.f & poor p.f respectively (b) poor p.f & More p.f respectively ( )

(c) Both are operates More p.f s (d) Both are operates poor p.fs

11. Transformer core is made of ( )

(a) Silicon sheet steel (b) chromium steel (c) low carbon steel (d) stainless teel

12. Open circuit test on a transformer is conducted to obtain ( )

(a) The leakage impedances (b) The ohmic loss (c) Hysteresis loss only (d) Core loss

13. Transformer action requires a ( )

(a) Constant magnetic flux (b) Increasing magnetic flux

(c) Alternating magnetic flux (d) Alternating electric flux.

14. The voltage regulation of transformer not depends on the following parameter ( )

(a) Resistance (b) Reactance (c) Power factor (d) Losses

15. Power input to a transformer on no load at rated voltage comprises predominantly ( )

(a) copper loss (b) hysteresis loss (c) core loss (d) eddy current loss.

16. The oil selected for transformer cooling should be free from ( )

(a) Alkalies (b) Acids (c) Sulphur (d) All of the above.

17. The no load current of the transformer is ___ percentage of the full load current ( )

(a) 10% (b) 3% (c) 40% (d) none of the above

18. In transformer, the supply frequency is increased with constant voltage then the eddy current

losses and hysteresis losses are respectively ( )

(a) Increases, decreases (b) constant,decreases

(c) decreases,constant (d) decreases, increases

19. The cu and iron losses are 80 w and 50w respectively, at full load, and then the cu loss and

iron loss are ___ at ¼ of the full load respectively, are ( )

(a) 10w, 15w (b) 80w, 2.6w (c) 5W, 50w (d) 50w, 205w

20. The flux which has low reluctance path has ф, at full load, then at half load the flux will be

(a) Doubled (b) half (c) Remain constant (d) None ( )

Signature of the Faulty Signature of the HOD

12. Open circuit test on a transformer is conducted to obtain ( )

(a) The leakage impedances (b) The ohmic loss (c) Hysteresis loss only (d) Core loss

13. Transformer action requires a ( )

(a) Constant magnetic flux (b) Increasing magnetic flux

(c) Alternating magnetic flux (d) Alternating electric flux.

14. The voltage regulation of transformer not depends on the following parameters ( )

(a) Resistance (b) Reactance (c) Power factor (d) Losses.

15. Power input to a transformer on no load at rated voltage comprises predominantly ( )

(a) copper loss (b) hysteresis loss (c) core loss (d) eddy current loss.

16. The oil selected for transformer cooling should be free from ( )

(a) Alkalies (b) Acids (c) Sulphur (d) All of the above.

17. The no load current of the transformer is ___ percentage of the full load current ( )

(a) 10% (b) 3% (c) 40% (d) none of the above

18. In transformer, the supply frequency is increased with constant voltage then the eddy current

losses and hysteresis losses are respectively ( )

(a) Increases, decreases (b) constant,decreases

(c) decreases,constant (d) decreases, increases

19. The cu and iron losses are 80 w and 50w respectively, at full load, and then the cu loss and

iron loss are ___ at ¼ of the full load respectively, are ( )

(a) 10w, 15w (b) 80w, 2.6w (c) 5W, 50w (d) 50w, 205w

20. The flux which has low reluctance path has ф, at full load, then at half load the flux will be

(a) Doubled (b) half (c) Remain constant (d) None ( )

Signature of the Faulty Signature of the HOD

G.PULLAIAH COLLEGE OF ENGINEERING & TECHNOLOGY (AT)

II.B.Tech, II- Sem. Objective – MID TERM-I Exam SET-4

Branch: EEE

Sub: ELECTRICAL MACHINES-II Date:03/03/2018

Time: 20 min Max.Marks:10

Regd.No…………………………………….

================================================================

Note: Answer the ALL Questions. 1. The oil selected for transformer cooling should be free from ( )

(a) Alkalies (b) Acids (c) Sulphur (d) All of the above.

2. The no load current of the transformer is _____ percentage of the full load current( )

(a) 10% (b) 3% (c) 40% (d) none of the above

3. In transformer, the supply frequency is increased with constant voltage then the eddy current

losses and hysteresis losses are respectively ( )

(a) Increases, decreases (b) constant, decreases

(c) Decreases, constant (d) decreases, increases

4. The cu and iron losses are 80 w and 50w respectively, at full load, and then the cu loss and

iron loss are ___ at ¼ of the full load respectively, are ( )

(a) 10w, 15w (b) 80w, 2.6w (c) 5W, 50w (d) 50w, 205w

5. The flux which has low reluctance path has ф, at full load, then at half load the flux will be

(a) Doubled (b) half (c) Remain constant (d) None ( )

6. Scott connections are used for

(a) 1-ф to 3-ф transformation (b) 3-ф to 1-ф transformation ( )

(c) 3-ф to 2-ф transformation (d) none

7. What is the advantage of three single phase transformers over the single three phase

transformer?

Ans:

8. Which of the following connections is best suited for 3-phase, 4-wire service?

(a) delta-delta (b) star-star (c) delta-star (d) star-delta ( )

9. In a three phase Y-Y transformer connection, neutral is fundamental to the ( )

(a) Suppression of harmonics (b) passage of unbalanced currents due to unbalanced loads

(c) Provision of dual electric service (d) None

10. A 200KVA transformer has an iron loss of 1 KW and full load cu loss of 2 KW. Its load

KVA corresponding to maximum efficiency is ______KVA. ( )

(a) 100 (b) 141.4 (c) 50 (d) 200

G.PULLAIAH COLLEGE OF ENGINEERING & TECHNOLOGY (AT)

II.B.Tech, II- Sem. Objective – MID TERM-I Exam SET-4

Branch: EEE(A & B Sections)

Sub: ELECTRICAL MACHINES-II Date:03/03/18

Time: 20 min Max.Marks:10

Regd.No…………………………………….

================================================================

Note: Answer the ALL Questions. 1. The oil selected for transformer cooling should be free from ( )

(a) Alkalies (b) Acids (c) Sulphur (d) All of the above.

2. The no load current of the transformer is _____ percentage of the full load current( )

(a) 10% (b) 3% (c) 40% (d) none of the above

3. In transformer, the supply frequency is increased with constant voltage then the eddy current

losses and hysteresis losses are respectively ( )

(a) Increases, decreases (b) constant, decreases

(c) Decreases, constant (d) decreases, increases

4. The cu and iron losses are 80 w and 50w respectively, at full load, and then the cu loss and

iron loss are ___ at ¼ of the full load respectively, are ( )

(a) 10w, 15w (b) 80w, 2.6w (c) 5W, 50w (d) 50w, 205w

5. The flux which has low reluctance path has ф, at full load, then at half load the flux will be

(a) Doubled (b) half (c) Remain constant (d) None ( )

6. Scott connections are used for

(a) 1-ф to 3-ф transformation (b) 3-ф to 1-ф transformation ( )

(c) 3-ф to 2-ф transformation (d) none

7. What is the advantage of three single phase transformers over the single three phase

transformer?

Ans:

8. Which of the following connections is best suited for 3-phase, 4-wire service?

(a) delta-delta (b) star-star (c) delta-star (d) star-delta ( )

9. In a three phase Y-Y transformer connection, neutral is fundamental to the ( )

(a) Suppression of harmonics (b) passage of unbalanced currents due to unbalanced loads

(c) Provision of dual electric service (d) None

10. A 200KVA transformer has an iron loss of 1 KW and full load cu loss of 2 KW. Its load

KVA corresponding to maximum efficiency is ______KVA. ( )

(a) 100 (b) 141.4 (c) 50 (d) 200

11. Scott connections are used for

(a) 1-ф to 3-ф transformation (b) 3-ф to 1-ф transformation ( )

(c) 3-ф to 2-ф transformation (d) none

12. In two parallel connected transformers, if the ratio of Xa/Ra > Xb/Rb, then transformer A

and transformer B are operates at a

(a) More p.f & poor p.f respectively (b) poor p.f & More p.f respectively ( )

(c) Both are operates More p.f s (d) Both are operates poor p.fs

13. Which of the following connections is best suited for 3-phase, 4-wire service?

(a) delta-delta (b) star-star (c) delta-star (d) delta-star ( )

14. In a three phase Y-Y transformer connection, neutral is fundamental to the ( )

(a) Suppression of harmonics (b) passage of unbalanced currents due to unbalanced loads

(c) Provision of dual electric service (d) none

15. A 200KVA transformer has an iron loss of 1 KW and full load cu loss of 2 KW. Its load

KVA corresponding to maximum efficiency is ______KVA. ( )

(a) 100 (b) 141.4 (c) 50 (d) 200

16. Transformer core is made of ( )

(a) Silicon sheet steel (b) chromium steel (c) low carbon steel(d) stainless steel

17. Open circuit test on a transformer is conducted to obtain ( )

(a) The leakage impedances (b) The ohmic loss (c) Hysteresis loss only (d) Core loss

18. Transformer action requires a ( )

(a) Constant magnetic flux (b) Increasing magnetic flux

(c) Alternating magnetic flux (d) Alternating electric flux.

19. The voltage regulation of transformer not depends on the following parameters( )

(a) Resistance (b) Reactance (c) Power factor (d) Losses

20. Power input to a transformer on no load at rated voltage comprises predominantly

(a) copper loss (b) hysteresis loss (c) core loss (d) eddy current loss. ( )

Signature of the Faulty Signature of the HOD

11. Scott connections are used for

(a) 1-ф to 3-ф transformation (b) 3-ф to 1-ф transformation ( )

(c) 3-ф to 2-ф transformation (d) none

12. In two parallel connected transformers, if the ratio of Xa/Ra > Xb/Rb, then transformer A

and transformer B are operates at a

(a) More p.f & poor p.f respectively (b) poor p.f & More p.f respectively ( )

(c) Both are operates More p.f s (d) Both are operates poor p.fs

13. Which of the following connections is best suited for 3-phase, 4-wire service?

(a) delta-delta (b) star-star (c) delta-star (d) delta-star ( )

14. In a three phase Y-Y transformer connection, neutral is fundamental to the ( )

(a) Suppression of harmonics (b) passage of unbalanced currents due to unbalanced loads

(c) Provision of dual electric service (d) none

15. A 200KVA transformer has an iron loss of 1 KW and full load cu loss of 2 KW. Its load

KVA corresponding to maximum efficiency is ______KVA. ( )

(a) 100 (b) 141.4 (c) 50 (d) 200

16. Transformer core is made of ( )

(a) Silicon sheet steel (b) chromium steel (c) low carbon steel(d) stainless steel

17. Open circuit test on a transformer is conducted to obtain ( )

(a) The leakage impedances (b) The ohmic loss (c) Hysteresis loss only (d) Core loss

18. Transformer action requires a ( )

(a) Constant magnetic flux (b) Increasing magnetic flux

(c) Alternating magnetic flux (d) Alternating electric flux.

19. The voltage regulation of transformer not depends on the following parameters ( )

(a) Resistance (b) Reactance (c) Power factor (d) Losses

20. Power input to a transformer on no load at rated voltage comprises predominantly

(a) copper loss (b) hysteresis loss (c) core loss (d) eddy current loss. ( )

Signature of the Faulty Signature of the HOD