Code No: RR211001
RR
Set No. 2
in
II B.Tech I Semester Supplementary Examinations,June 2010 ELECTRICAL TECHNOLOGY Common to Bio-Medical Engineering, Electronics And Control Engineering, Electronics And Instrumentation Engineering Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ?????
ld .
1. (a) Define regulation of a transformer. Derive the expression for the regulation. [2+4]
(b) Explain with neat circuit diagrams, the open circuit and short circuit tests to be carried out in the laboratory on a 1.5 kVA, 230 V / 40 V, 50 Hz, 1-phase transformer, for the determination of the parameters of the equivalent circuit. [10]
or
2. (a) Discuss the function of an ac tacho meter. Explain its construction and operations.
(b) What are the applications of stepper motor and synchros?
[10+6]
3. (a) Explain how a.c. voltage generated is converted to D.C. voltage in a generator?
uW
(b) What is the main purpose of laminating the armature core of a D.C. Generator. (c) A 4-pole, long shunt, lap wound generator supplies 25kw at a terminal voltage of 500 V. The armature resistance is 0.03Ω, series field resistance is 0.04Ω and shunt field resistance is 200Ω. The brush drop may be taken as 1 V. Determine the e m f generated. [5+3+8] 4. (a) What is the significance of the back e.m.f. of a D.C. Motor? (b) Deduce the condition for maximum power for a D.C. Motor?
nt
(c) A 220V shunt motor with an armature resistance of 0.5Ω is excited to give constant main field. At full load the motor runs at 500 rpm and takes an armature current of 30A. If a resistance of 1.0Ω is placed in the armature circuit, find the speed at
Aj
i. full-load torque ii. double full-load torque.
[4+4+8]
5. (a) Compare between core type and shell type transformers. (b) Derive the emf equation of a 1-Phase transformer and calculate the emf / turn, if the flux is 0.015 wb at a frequency of 50 Hz. [8+8]
6. (a) Explain the constructional details of a synchronous machine giving the reasons for making two different types of rotors.
1
Code No: RR211001
RR
Set No. 2
(b) A 100KVA, 3000V, 50 Hz,3-phase star connected alternator has effective armature resistance of 0.2 ohm. A field current of 40 A produces short circuit current of 200A and on open circuit e.m.f of 1100V(line value). calculate the full load percentage regulation at a power factor of 0.8 lagging. [8+8] 7. (a) Explain the principle of working of synchronous motor.
in
(b) A 3 phase, 1385 V star connected synchronous motor having synchronous reactance of 2 ohm per phase and negligible resistance takes an input of 207.8 kW with an induced e.m.f of 916.5V per phase. Calculate the motor line current and its power factor. [8+8]
ld .
8. (a) With a neat sketch, explain the construction of a 3-phase induction motor.
(b) 3-phase, 4-pole, 1440 rpm, 50 Hz induction motor has star-connected rotor winding, having a resistance of 0.2Ω per phase and a standstill leakage reactance of 1Ω per phase. When the stator is energised at rated voltage and frequency, the rotor-induced e.m.f at standstill is 120 V per phase.
uW
or
i. calculate the rotor current, rotor power factor and torque both at starting and at full load and compare these results ii. If an external resistance of 1 ohm per phase is inserted in rotor circuit, calculate rotor current, rotor power factor and torque at the time of starting. [8+8]
Aj
nt
?????
2
Code No: RR211001
RR
Set No. 4
in
II B.Tech I Semester Supplementary Examinations,June 2010 ELECTRICAL TECHNOLOGY Common to Bio-Medical Engineering, Electronics And Control Engineering, Electronics And Instrumentation Engineering Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ?????
1. (a) Explain how a.c. voltage generated is converted to D.C. voltage in a generator?
ld .
(b) What is the main purpose of laminating the armature core of a D.C. Generator. (c) A 4-pole, long shunt, lap wound generator supplies 25kw at a terminal voltage of 500 V. The armature resistance is 0.03Ω, series field resistance is 0.04Ω and shunt field resistance is 200Ω. The brush drop may be taken as 1 V. Determine the e m f generated. [5+3+8]
or
2. (a) What is the significance of the back e.m.f. of a D.C. Motor?
(b) Deduce the condition for maximum power for a D.C. Motor?
uW
(c) A 220V shunt motor with an armature resistance of 0.5Ω is excited to give constant main field. At full load the motor runs at 500 rpm and takes an armature current of 30A. If a resistance of 1.0Ω is placed in the armature circuit, find the speed at i. full-load torque ii. double full-load torque.
[4+4+8]
3. (a) Discuss the function of an ac tacho meter.Explain its construction and operations.
(b) What are the applications of stepper motor and synchros?
[10+6]
nt
4. (a) Define regulation of a transformer. Derive the expression for the regulation. [2+4]
Aj
(b) Explain with neat circuit diagrams, the open circuit and short circuit tests to be carried out in the laboratory on a 1.5 kVA, 230 V / 40 V, 50 Hz, 1-phase transformer, for the determination of the parameters of the equivalent circuit. [10]
5. (a) With a neat sketch, explain the construction of a 3-phase induction motor. (b) 3-phase, 4-pole, 1440 rpm, 50 Hz induction motor has star-connected rotor winding, having a resistance of 0.2Ω per phase and a standstill leakage reactance of 1Ω per phase. When the stator is energised at rated voltage and frequency, the rotor-induced e.m.f at standstill is 120 V per phase. i. calculate the rotor current, rotor power factor and torque both at starting and at full load and compare these results
3
Code No: RR211001
RR
Set No. 4
ii. If an external resistance of 1 ohm per phase is inserted in rotor circuit, calculate rotor current, rotor power factor and torque at the time of starting. [8+8] 6. (a) Explain the principle of working of synchronous motor.
ld .
7. (a) Compare between core type and shell type transformers.
in
(b) A 3 phase, 1385 V star connected synchronous motor having synchronous reactance of 2 ohm per phase and negligible resistance takes an input of 207.8 kW with an induced e.m.f of 916.5V per phase. Calculate the motor line current and its power factor. [8+8]
(b) Derive the emf equation of a 1-Phase transformer and calculate the emf / turn, if the flux is 0.015 wb at a frequency of 50 Hz. [8+8] 8. (a) Explain the constructional details of a synchronous machine giving the reasons for making two different types of rotors.
or
(b) A 100KVA, 3000V, 50 Hz,3-phase star connected alternator has effective armature resistance of 0.2 ohm. A field current of 40 A produces short circuit current of 200A and on open circuit e.m.f of 1100V(line value). calculate the full load percentage regulation at a power factor of 0.8 lagging. [8+8]
Aj
nt
uW
?????
4
Code No: RR211001
RR
Set No. 1
1. (a) What is the significance of the back e.m.f. of a D.C. Motor?
ld .
(b) Deduce the condition for maximum power for a D.C. Motor?
in
II B.Tech I Semester Supplementary Examinations,June 2010 ELECTRICAL TECHNOLOGY Common to Bio-Medical Engineering, Electronics And Control Engineering, Electronics And Instrumentation Engineering Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ?????
i. full-load torque ii. double full-load torque.
or
(c) A 220V shunt motor with an armature resistance of 0.5Ω is excited to give constant main field. At full load the motor runs at 500 rpm and takes an armature current of 30A. If a resistance of 1.0Ω is placed in the armature circuit, find the speed at [4+4+8]
2. (a) Compare between core type and shell type transformers.
uW
(b) Derive the emf equation of a 1-Phase transformer and calculate the emf / turn, if the flux is 0.015 wb at a frequency of 50 Hz. [8+8] 3. (a) Explain how a.c. voltage generated is converted to D.C. voltage in a generator? (b) What is the main purpose of laminating the armature core of a D.C. Generator. (c) A 4-pole, long shunt, lap wound generator supplies 25kw at a terminal voltage of 500 V. The armature resistance is 0.03Ω, series field resistance is 0.04Ω and shunt field resistance is 200Ω. The brush drop may be taken as 1 V. Determine the e m f generated. [5+3+8]
nt
4. (a) With a neat sketch, explain the construction of a 3-phase induction motor.
Aj
(b) 3-phase, 4-pole, 1440 rpm, 50 Hz induction motor has star-connected rotor winding, having a resistance of 0.2Ω per phase and a standstill leakage reactance of 1Ω per phase. When the stator is energised at rated voltage and frequency, the rotor-induced e.m.f at standstill is 120 V per phase. i. calculate the rotor current, rotor power factor and torque both at starting and at full load and compare these results ii. If an external resistance of 1 ohm per phase is inserted in rotor circuit, calculate rotor current, rotor power factor and torque at the time of starting. [8+8]
5. (a) Explain the constructional details of a synchronous machine giving the reasons for making two different types of rotors.
5
Code No: RR211001
RR
Set No. 1
(b) A 100KVA, 3000V, 50 Hz,3-phase star connected alternator has effective armature resistance of 0.2 ohm. A field current of 40 A produces short circuit current of 200A and on open circuit e.m.f of 1100V(line value). calculate the full load percentage regulation at a power factor of 0.8 lagging. [8+8] 6. (a) Explain the principle of working of synchronous motor.
in
(b) A 3 phase, 1385 V star connected synchronous motor having synchronous reactance of 2 ohm per phase and negligible resistance takes an input of 207.8 kW with an induced e.m.f of 916.5V per phase. Calculate the motor line current and its power factor. [8+8]
ld .
7. (a) Define regulation of a transformer. Derive the expression for the regulation. [2+4]
or
(b) Explain with neat circuit diagrams, the open circuit and short circuit tests to be carried out in the laboratory on a 1.5 kVA, 230 V / 40 V, 50 Hz, 1-phase transformer, for the determination of the parameters of the equivalent circuit. [10] 8. (a) Discuss the function of an ac tachometer. Explain its construction and operations. (b) What are the applications of stepper motor and synchros?
Aj
nt
uW
?????
6
[10+6]
Code No: RR211001
RR
Set No. 3
in
II B.Tech I Semester Supplementary Examinations,June 2010 ELECTRICAL TECHNOLOGY Common to Bio-Medical Engineering, Electronics And Control Engineering, Electronics And Instrumentation Engineering Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ?????
1. (a) Explain how a.c. voltage generated is converted to D.C. voltage in a generator?
ld .
(b) What is the main purpose of laminating the armature core of a D.C. Generator. (c) A 4-pole, long shunt, lap wound generator supplies 25kw at a terminal voltage of 500 V. The armature resistance is 0.03Ω, series field resistance is 0.04Ω and shunt field resistance is 200Ω. The brush drop may be taken as 1 V. Determine the e m f generated. [5+3+8]
or
2. (a) Compare between core type and shell type transformers.
(b) Derive the emf equation of a 1-Phase transformer and calculate the emf / turn, if the flux is 0.015 wb at a frequency of 50 Hz. [8+8] 3. (a) With a neat sketch, explain the construction of a 3-phase induction motor.
uW
(b) 3-phase, 4-pole, 1440 rpm, 50 Hz induction motor has star-connected rotor winding, having a resistance of 0.2Ω per phase and a standstill leakage reactance of 1Ω per phase. When the stator is energised at rated voltage and frequency, the rotor-induced e.m.f at standstill is 120 V per phase.
nt
i. calculate the rotor current, rotor power factor and torque both at starting and at full load and compare these results ii. If an external resistance of 1 ohm per phase is inserted in rotor circuit, calculate rotor current, rotor power factor and torque at the time of starting. [8+8]
4. (a) Discuss the function of an ac tachometer. Explain its construction and operations.
Aj
(b) What are the applications of stepper motor and synchros?
[10+6]
5. (a) Define regulation of a transformer. Derive the expression for the regulation. [2+4]
(b) Explain with neat circuit diagrams, the open circuit and short circuit tests to be carried out in the laboratory on a 1.5 kVA, 230 V / 40 V, 50 Hz, 1-phase transformer, for the determination of the parameters of the equivalent circuit. [10]
6. (a) What is the significance of the back e.m.f. of a D.C. Motor?
7
Code No: RR211001
RR
Set No. 3
(b) Deduce the condition for maximum power for a D.C. Motor? (c) A 220V shunt motor with an armature resistance of 0.5Ω is excited to give constant main field. At full load the motor runs at 500 rpm and takes an armature current of 30A. If a resistance of 1.0Ω is placed in the armature circuit, find the speed at i. full-load torque ii. double full-load torque.
in
[4+4+8]
7. (a) Explain the constructional details of a synchronous machine giving the reasons for making two different types of rotors.
ld .
(b) A 100KVA, 3000V, 50 Hz,3-phase star connected alternator has effective armature resistance of 0.2 ohm. A field current of 40 A produces short circuit current of 200A and on open circuit e.m.f of 1100V(line value). calculate the full load percentage regulation at a power factor of 0.8 lagging. [8+8] 8. (a) Explain the principle of working of synchronous motor.
or
(b) A 3 phase, 1385 V star connected synchronous motor having synchronous reactance of 2 ohm per phase and negligible resistance takes an input of 207.8 kW with an induced e.m.f of 916.5V per phase. Calculate the motor line current and its power factor. [8+8]
Aj
nt
uW
?????
8