Explain working principle of transformer in detail and also derive E.M.F. Equation of transformer.
[7 marks]Develop equivalent circuit of a 1-phase transformer. Draw the phasor diagrams for no-load and load conditions.
[7 marks]Why 1-phase induction is not self-start? Explain starting methods of 1-phase induction motor.
[7 marks]Explain 3-point starter use to start DC motor.
[7 marks]Obtain the equivalent circuit of a 200/400 –V, 50 Hz, 1 Phase Transformer from the following test data, O.C.Test: 200 V, 0.7 A, 70 W - on L.V. side S.C. Test: 15 V, 10 A, 85 W - on H.V. side. Calculate the secondary voltage when delivering 5 KW at 0.8 p.f. lagging, the primary voltage being 200V.
[7 marks]What is armature reaction? What are the methods to improve armature reaction?
[7 marks]Explain Equivalent circuit of three phase induction motor.
[7 marks]Draw and explain the internal and external characteristics of d.c. shunt generators.
[7 marks]Explain different speed control methods for 3 phase induction motor.
[7 marks]Explain Parallel operation of two three phase transformers with necessary conditions.
[7 marks]A 4-pole, lap-wound, d.c. shunt generator has a useful flux per pole of 0.07 Wb. The armature winding consists of 220 turns each of 0.004 Ω resistance. Calculate the terminal voltage when running at 900 r.p.m. if the armature current is 50 A.
[7 marks]What is voltage regulation? Explain synchronous impedance method for finding voltage regulation of alternator.
[7 marks]What is hunting? Why damper winding use to reduce hunting? What are the applications of synchronous motor?
[7 marks]State and explain condition of synchronizing alternator with infinite bus bar.
[7 marks]Explain the Swinburne’s test of a d.c. machine for finding losses with necessary Diagram.1
[7 marks]Derive the condition for Maximum torque for induction motor and explain Torque - Slip characteristics.
[7 marks]An 18.65-kW, 4-pole, 50-Hz, 3-phase induction motor has friction and windage Losses of 2.5 per cent of the output. The full-load slip is 4%. Compute for full load (a) the rotor Cu loss (b) the rotor input (c) the shaft torque (d) the gross electromagnetic torque.
[7 marks]