| ELECTRICAL MACHINES |
| PAPER NO. 3 |
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IC-203 ELECTRICAL MACHINES (B.Tech 3rd Semester,2052) Time : 3 Hours Maximum Marks : 60 NOTE:- This paper consist of Three Sections. Section A is compulsory. Do any Four questions from Section B and any two questions from Section C Section-A Marks : 20 1(a) Explain the following terms as applied to d.c. armarure winding : (i) Front Pitch (ii) Back Pitch (b) In what type of d.c. machine wave winding is employed and why ? (c) Sketch the following types of d.c. generator : (i) Shunt (ii) Compound (d) What properties should a good transformer oil possess ? (e) Discuss briefly Crawling. (f) Explain starting of repulsion motor. (g) Write applications of a synchronous motor. (h) Draw connection diagram of a capacitor start and capacitor run single-phase induction motor. (i) Explain purpose of providing damper winding in synchronous machine ? (j) What is function of former in d.c. machine ? Section-B Marks:5 Each 2. What is difference between short shunt and long shunt compound generator ? 3. Write a note on Equilizer rings. 4. Explain plugging method of bracking d.c. motors. 5. Explain how T-T connections is made for 3-φ to 3-φ operation in transformer. 6. What is meant by equilent resistance of a transformer ? How may it be calculated in primary terms and secondary terms ? Section-C Marks : 10 Each 7. A 6 pole, 3-&phi, 50 Hz, induction motor develops maximum torque of 300 N-m at a speed of 960 rpm. Determine the torque exerted by the motor at 5% slip. The rotor resistance per phase is 0.6 ω 8. A 50 Hz, 1-φ transformer has a turn ratio of 5. The resistance are 0.8 ω and 0.02 ω and resistances are 4 ω and 0.12 ω for h.v. and l.v. winding respectively. Find : (a) The voltage to be applied to the h.v. side to obtain full load current of 180 A in the l.v. winding on short circuit. (b) The power factor on short circuit Draw the equilent circuit and vector diagram. 9. Write short notes on any two of the following : (a) Universal motor (b) Stepper motor (c) Blocked rotor test method of speed control of induction motor. |
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