5 MARKS QUESTIONS :
1. Derive the EMF equation of a dc generator ?
2. Explain with proper diagram the working principle of dc motor ?
3. A 4500/16000v,1500kvA.50Hz transformer has the following parameters : R1=0.03 ohm R2=0.44 ohm R0=1688 ohm X1=0.092 ohm X2=1.34 ohm X0=256 ohm The transformer is supplying full-load at a power factor of 0.8 lagging. Using exact equivalent circuit, find the input current.
4. Explain the working principle of a single phase auto transformer ?
5. Discuss briefly the essential and desirable conditions to be fulfilled for operating two 3 phase transformers in parallel ?
6. A 75kW dc shunt generator is operated at 230v.The stray losses are 1810W and shunt field circuit draws 5.35A.The armature circuit has a resistance of 0.035 ohm and brush drop is 2.2 V. Calculate i)total losses ii)output of prime mover iii)efficiency at rated load.
7. Explain the construction of a single phase transformer ?
8. Explain working principle of commutator ?
9. Write down the types of DC generator ?
10. Describe armature reaction in dc generator ?
11. Describe classification of a DC motor ?
12. What is the significance of back EMF ?
13. Derive the EMF equation of a transformer ?
14. Explain speed control of DC motor ?
15. Explain transformer Test ?
16. Distinguish between lap winding and wave winding ?
17. A 4-pole generator having wave wound armature winding has 51 slots, each slot containing 20 conductors. What will be the voltage generated in the machine when driven at 1500 rpm assuming the flux per pole to be 7.0m wb ?
18. Explain iron loss in armature ?
19. Explain constructional feature DC generator ?
20. Explain characteristics of DC generator ?
21. Explain speed control of DC motor ?
22. Explain the EMF equation of a transformer ?
23. Explain field control method of DC shunt motor for regulating the speed ?
24. Derive EMF equation of DC generator ?
25. Explain speed control of DC shunt motors by flux control method .
26. Write down the maintenance schedule of power transformer ?
27. Explain uses of auto transformer ?
28. Explain armature reaction in DC generator ?
29. Efficiency of DC motor by break test method .
30. Derive the condition for maximum efficiency of a transformer ?
31. Explain the torque speed characteristics of DC series motor ?
7 MARKS QUESTIONS:-
1. A 30kW,300V dc shunt generator has armature and field resistance of 0.05 ohm 100 ohm respectively. Calculate the total power developed by the armature when it delivers full load output.
2. A 220V dc shunt motor having an armature resistance of 0.25 ohm carries an armature current of 50A and runs at 600 rpm. If the flux is reduced by 10% by field regulator, find the speed assuming load torque remains the same.
3. Discuss about the open circuit and short-circuit test of a single phase transformer ?
4. Derive an expression for saving in conductor material in an auto transformer over a two-winding transformer of equal rating ?
5. Explain with suitable diagram the delta star connection for a three phase transformer ?
6. Explain in detail the different methods of speed control of a dc motor ?
7. A 40kvA distribution transformer has iron loss of 500W and full-load copper loss of 500W.The transformer is supplying a lighting load(unity p.f.). The load cycle is as under : Full load for 4 hours; half full-load for 8 hours ;and no-load for 12 hours. Calculate the all day efficiency of the transformer.
8. Write short notes on any two :- a)Swinburne’s Test b)On-load phasor diagram of single phase transformer. c)Types of dc machines.
9. A shunt generator delivers 450A at 230V and the resistance of the shunt field and armature are 50 ohm and 0.03 ohm respectively. Calculate the generated EMF .
10. A 4 pole, lap wound dc shunt generator has a useful per pole of 0.07 wb. The armature winding consists of 220 turns each of 0.004 ohm resistance. Calculate the terminal voltage when running at 900 rpm. If the armature current is 50 A.
11. A 10kW, 250V6-pole dc shunt generator runs 1000 rpm. When delivering full-load the armature has 534 lap-connected conductors .Full-load cu loss is 0.64kW. The total brush drop is 1 volt. Determine the flux per pole. Neglect shunt current.
12. A 440V, shunt motor has armature resistance of 0.8 ohm and field resistance of 200 ohm. Determine the back EMF when giving an output of 7.46kW at 85% efficiency .
13. A 220V dc shunt motor runs at 500 rpm when the armature current is 50A. Calculate the speed if the torque is doubled. Given that Ra=0.2 ohm .
14. Write down the necessity of a starter and explain the 3-point starter ?
15. The maximum flux density in the core of a 250/3000 volts, 50Hz single phase transformer is 1.2 wb/m2. If the EMF per turn is 8 volts, Determine
i)primary and secondary turns
ii)area of core.
16. Describe the efficiency of a transformer ?
17. Write down the short note on pole pitch, coil span, back pitch and front pitch.
18. A 4-pole DC generator runs at 750 rpm and generates an EMF of 240V. The armature is wave wound and has 792 conductors. Find out the flux/pole.
1. Derive the EMF equation of a dc generator ?
2. Explain with proper diagram the working principle of dc motor ?
3. A 4500/16000v,1500kvA.50Hz transformer has the following parameters : R1=0.03 ohm R2=0.44 ohm R0=1688 ohm X1=0.092 ohm X2=1.34 ohm X0=256 ohm The transformer is supplying full-load at a power factor of 0.8 lagging. Using exact equivalent circuit, find the input current.
4. Explain the working principle of a single phase auto transformer ?
5. Discuss briefly the essential and desirable conditions to be fulfilled for operating two 3 phase transformers in parallel ?
6. A 75kW dc shunt generator is operated at 230v.The stray losses are 1810W and shunt field circuit draws 5.35A.The armature circuit has a resistance of 0.035 ohm and brush drop is 2.2 V. Calculate i)total losses ii)output of prime mover iii)efficiency at rated load.
7. Explain the construction of a single phase transformer ?
8. Explain working principle of commutator ?
9. Write down the types of DC generator ?
10. Describe armature reaction in dc generator ?
11. Describe classification of a DC motor ?
12. What is the significance of back EMF ?
13. Derive the EMF equation of a transformer ?
14. Explain speed control of DC motor ?
15. Explain transformer Test ?
16. Distinguish between lap winding and wave winding ?
17. A 4-pole generator having wave wound armature winding has 51 slots, each slot containing 20 conductors. What will be the voltage generated in the machine when driven at 1500 rpm assuming the flux per pole to be 7.0m wb ?
18. Explain iron loss in armature ?
19. Explain constructional feature DC generator ?
20. Explain characteristics of DC generator ?
21. Explain speed control of DC motor ?
22. Explain the EMF equation of a transformer ?
23. Explain field control method of DC shunt motor for regulating the speed ?
24. Derive EMF equation of DC generator ?
25. Explain speed control of DC shunt motors by flux control method .
26. Write down the maintenance schedule of power transformer ?
27. Explain uses of auto transformer ?
28. Explain armature reaction in DC generator ?
29. Efficiency of DC motor by break test method .
30. Derive the condition for maximum efficiency of a transformer ?
31. Explain the torque speed characteristics of DC series motor ?
7 MARKS QUESTIONS:-
1. A 30kW,300V dc shunt generator has armature and field resistance of 0.05 ohm 100 ohm respectively. Calculate the total power developed by the armature when it delivers full load output.
2. A 220V dc shunt motor having an armature resistance of 0.25 ohm carries an armature current of 50A and runs at 600 rpm. If the flux is reduced by 10% by field regulator, find the speed assuming load torque remains the same.
3. Discuss about the open circuit and short-circuit test of a single phase transformer ?
4. Derive an expression for saving in conductor material in an auto transformer over a two-winding transformer of equal rating ?
5. Explain with suitable diagram the delta star connection for a three phase transformer ?
6. Explain in detail the different methods of speed control of a dc motor ?
7. A 40kvA distribution transformer has iron loss of 500W and full-load copper loss of 500W.The transformer is supplying a lighting load(unity p.f.). The load cycle is as under : Full load for 4 hours; half full-load for 8 hours ;and no-load for 12 hours. Calculate the all day efficiency of the transformer.
8. Write short notes on any two :- a)Swinburne’s Test b)On-load phasor diagram of single phase transformer. c)Types of dc machines.
9. A shunt generator delivers 450A at 230V and the resistance of the shunt field and armature are 50 ohm and 0.03 ohm respectively. Calculate the generated EMF .
10. A 4 pole, lap wound dc shunt generator has a useful per pole of 0.07 wb. The armature winding consists of 220 turns each of 0.004 ohm resistance. Calculate the terminal voltage when running at 900 rpm. If the armature current is 50 A.
11. A 10kW, 250V6-pole dc shunt generator runs 1000 rpm. When delivering full-load the armature has 534 lap-connected conductors .Full-load cu loss is 0.64kW. The total brush drop is 1 volt. Determine the flux per pole. Neglect shunt current.
12. A 440V, shunt motor has armature resistance of 0.8 ohm and field resistance of 200 ohm. Determine the back EMF when giving an output of 7.46kW at 85% efficiency .
13. A 220V dc shunt motor runs at 500 rpm when the armature current is 50A. Calculate the speed if the torque is doubled. Given that Ra=0.2 ohm .
14. Write down the necessity of a starter and explain the 3-point starter ?
15. The maximum flux density in the core of a 250/3000 volts, 50Hz single phase transformer is 1.2 wb/m2. If the EMF per turn is 8 volts, Determine
i)primary and secondary turns
ii)area of core.
16. Describe the efficiency of a transformer ?
17. Write down the short note on pole pitch, coil span, back pitch and front pitch.
18. A 4-pole DC generator runs at 750 rpm and generates an EMF of 240V. The armature is wave wound and has 792 conductors. Find out the flux/pole.
19. *A 10kW , 250V,6-pole DC shunt generator has 3600 rpm when delivering full-load. The armature has 53 lap-connected conductors. Full-load cu loss is 0.60kW. The total brush drop is 1 volt. Determine the flux per pole. Neglect shunt current.
20. Write the EMF equation of DC generator?
21. A 440V shunt motor has armature resistance of 0.8 ohm and field resistance 0f 200 ohm. Determine EMF when giving an output of 7.4kW at 85% efficiency .
22. Write down the necessity of a starter and explain the 4-point starter ?
23. The maximum flux density in the core of a250/3000 volts,50Hz single phase transformer is 1.2wb/m2. If the EMF per turn is 8 volts ,Determine : i)primary and secondary turns ii)area of core
24. Describe the efficiency of a transformer ?
25. A 4-pole lap wound armature has 144 slots with two coil slides per slot each coil having two turns .If the flux per pole is 25mwb and the armature rotates at 650 rpm, What is induced voltage ?
26. A 50kW, 250 volt DC shunt generator has armature and field resistance of 0.08 ohm and 100 ohm respectively. Determine the armature power if (a)As generator delivering 50kW output (b)As a motor taking 50kW input power.
27. Explain role of inter poles and compensating winding in DC generator ?
28. An auto transformer is used to step down voltage level from 230V 200V while the load is 20kW at unit p.f. Neglecting losses and magnetising current. Find the current in different section of the winding.
29. Explain 3-point starter with neat sketch .
30. OC and SC test in transformer .
31. Explain commutation in DC generator ?
32. Explain the speed control method of a DC motor .
The end.
Best of luck
1 comments:
There is something wrong in the solution of problem no.10
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