Anna University Previous Years Question Papers

Question paper code: 77128

B.E./ B. TECH DEGREE EXAMINATION,APRIL/MAY-2015

Third semester

Electronics and communication Engineering

EE 6352- ELECRICAL ENGINEERING AND INSTRUMENTATION

(Regulation 2013)

Time- Three hour

Maximum mark-100

Answer all questions

PART A-10X2=20marks

1. Mention the advantages of star and delta system?

2. A 20V DC motor has an armature resistance of 0.06Ω and serious field resistance of 0.04Ω. If the motor input is 20 kw, Find the back emf of the motor and power developed in armature.

3. Distinguish between core and shell type transformer.

4. What is an deal transformer and how does it differ from a practical transformer.

5. Mention the characteristic features of synchronous motor?

6. Compare slip ring and squirrel cage type rotor.

7. A thermistor has a resistance tamperature coefficient ß of -5%/0c . If the resistance of the thermistor is 100Ω at 250c,what is the resistance as at 350c?

8. What is piezoelectric effect?

9. Compare analog and digital instruments.

10. Write the advantages and disadvantages of Anderson bridge?

Part B-5X16=80 marks

11.(a)(i) Explain the internal and external characteristics of DC generator.

(ii) A 10kw 250v, DC shunt generator is driven at 1000rpm. Armature circuit resistance is 0.15 Ω and the field current is 1.64 A when the terminal voltage is 250V. Rotational losses are to be 540W. Find at rated load armature induced emf, developed torque and efficiency.

(or)

(b)(i) Explain the characteristics of DC shunt and serious motor.

(ii) A 250V DC shunt motor has an armature resistance of 0.5Ω and a field resistance of 250Ω. When driving a constant load at 600rpm of the motor draws 21A. What will be the new speed of the motor if an additional 250Ω resistance is inserted in the field circuit?

12.(a)(i)A 20 KVA single phase transformer designed for 2000/200 V has the following constant: R1=2.5Ω,X1=8 Ω,R2=0.04 Ω and X2=0.07 Ω.Calculate the approximate value of the secondary terminal voltages and % regulation at full load and 0.8.p.f. lagging When primary applied voltage is 2000V.

(ii) Find “all day”efficiency of a transformer having maximum efficiency of 98% at 15KVA at unity power factor and loaded as follow:

12 hours- 2kw at 0.5p.f lag

6 hours- 12kw at 0.8p.f lag

6 hours- at no load

(or)

(b)(i) Deduced the equivalent circuit of transformer.

(ii)A 1100/110V,22KVA single phase transformer has primary resistance and reactance 2 Ω and 5Ω respectively. The secondary resistance and reactance are 0.02Ω and 0.045Ω respectively. Calculate:

1. Equation resistance and reactance of secondary referred to primary.

2. Total resistance and reactance referred to primary.

3. Equation resistance and reactance of primary referred to secondary.

4. Total resistance and reactance referred to secondary.

5. Total copper loss.

13. (a)(i) Give the constructional details of rotor of both salient pole and cylindrical rotor synchronous machines.

(ii) Explain the working principle of synchronous motor and also explain any two method of starting of synchronous motor.

(or)

(b)(i)Explain double field revolving theory of single phase induction motor.

(ii) Explain the working of split phase capacitor start motor.

(iii) A 3 phase induction motro runs at 1140rpm at full load when supplied with power from a 60 Hz , 3 phase line calculate the number of poles and full load of speed, Frequency of rotor voltage.

14.(a)(i) Explain the construction and principle of working of a LVDT. Explain how the magnitude and direction of the displacement of core of LVDT detected?

(ii) Describe the working and construction of RTD. Describe the material used for RTD along with their properties.

(or)

(b)(i)Define the following static characteristics:

1. Static sensitivity

2. Linearity

3. precision

4. Accuracy

5. Threshold

(ii) Discuss the error in measurement.

15.(a)(i) Explain the construction and working of digital mulitmeter with all the self diagnostic features.

(ii) Explain the working of ramp type digital voltmeter.

(or)

(b)(i) Derive the bridge balance equation of Schering bridge.

(ii) How is low resistance measured using Kelvin double bridge?

Question paper code: 77128

B.E./ B. TECH DEGREE EXAMINATION,APRIL/MAY-2015

Third semester

Electronics and communication Engineering

EE 6352- ELECRICAL ENGINEERING AND INSTRUMENTATION

(Regulation 2013)

Time- Three hour

Maximum mark-100

Answer all questions

PART A-10X2=20marks

1. Mention the advantages of star and delta system?

2. A 20V DC motor has an armature resistance of 0.06Ω and serious field resistance of 0.04Ω. If the motor input is 20 kw, Find the back emf of the motor and power developed in armature.

3. Distinguish between core and shell type transformer.

4. What is an deal transformer and how does it differ from a practical transformer.

5. Mention the characteristic features of synchronous motor?

6. Compare slip ring and squirrel cage type rotor.

7. A thermistor has a resistance tamperature coefficient ß of -5%/0c . If the resistance of the thermistor is 100Ω at 250c,what is the resistance as at 350c?

8. What is piezoelectric effect?

9. Compare analog and digital instruments.

10. Write the advantages and disadvantages of Anderson bridge?

Part B-5X16=80 marks

11.(a)(i) Explain the internal and external characteristics of DC generator.

(ii) A 10kw 250v, DC shunt generator is driven at 1000rpm. Armature circuit resistance is 0.15 Ω and the field current is 1.64 A when the terminal voltage is 250V. Rotational losses are to be 540W. Find at rated load armature induced emf, developed torque and efficiency.

(or)

(b)(i) Explain the characteristics of DC shunt and serious motor.

(ii) A 250V DC shunt motor has an armature resistance of 0.5Ω and a field resistance of 250Ω. When driving a constant load at 600rpm of the motor draws 21A. What will be the new speed of the motor if an additional 250Ω resistance is inserted in the field circuit?

12.(a)(i)A 20 KVA single phase transformer designed for 2000/200 V has the following constant: R1=2.5Ω,X1=8 Ω,R2=0.04 Ω and X2=0.07 Ω.Calculate the approximate value of the secondary terminal voltages and % regulation at full load and 0.8.p.f. lagging When primary applied voltage is 2000V.

(ii) Find “all day”efficiency of a transformer having maximum efficiency of 98% at 15KVA at unity power factor and loaded as follow:

12 hours- 2kw at 0.5p.f lag

6 hours- 12kw at 0.8p.f lag

6 hours- at no load

(or)

(b)(i) Deduced the equivalent circuit of transformer.

(ii)A 1100/110V,22KVA single phase transformer has primary resistance and reactance 2 Ω and 5Ω respectively. The secondary resistance and reactance are 0.02Ω and 0.045Ω respectively. Calculate:

1. Equation resistance and reactance of secondary referred to primary.

2. Total resistance and reactance referred to primary.

3. Equation resistance and reactance of primary referred to secondary.

4. Total resistance and reactance referred to secondary.

5. Total copper loss.

13. (a)(i) Give the constructional details of rotor of both salient pole and cylindrical rotor synchronous machines.

(ii) Explain the working principle of synchronous motor and also explain any two method of starting of synchronous motor.

(or)

(b)(i)Explain double field revolving theory of single phase induction motor.

(ii) Explain the working of split phase capacitor start motor.

(iii) A 3 phase induction motro runs at 1140rpm at full load when supplied with power from a 60 Hz , 3 phase line calculate the number of poles and full load of speed, Frequency of rotor voltage.

14.(a)(i) Explain the construction and principle of working of a LVDT. Explain how the magnitude and direction of the displacement of core of LVDT detected?

(ii) Describe the working and construction of RTD. Describe the material used for RTD along with their properties.

(or)

(b)(i)Define the following static characteristics:

1. Static sensitivity

2. Linearity

3. precision

4. Accuracy

5. Threshold

(ii) Discuss the error in measurement.

15.(a)(i) Explain the construction and working of digital mulitmeter with all the self diagnostic features.

(ii) Explain the working of ramp type digital voltmeter.

(or)

(b)(i) Derive the bridge balance equation of Schering bridge.

(ii) How is low resistance measured using Kelvin double bridge?