--- Content provided by FirstRanker.com --- State Kirchhoff’s laws. Define RMS value and Average value of an AC signal. Define Power factor. What are the causes of low power factor? What are the applications of DC motors? Write the EMF equation of a DC generator. Define transformation ratio of a transformer. What are the losses in the transformer? Define slip and write its expression. What are the advantages of rotating field type alternator?
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PART-B (5 x 10 = 50 Marks)
Note: Answer any five questions. Each question carries 10 marks
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- a) State and explain Thevenin’s theorem.
b) For the circuit shown below, find the current through 6 Ω resistor using nodal analysis.
- For the circuit shown below, find the current through 5 Ω resistor using superposition theorem.
- a) Derive the RMS value and Average value of a sinusoidal alternating quantity.
b) A 50 Hz sinusoidal voltage has a maximum value of 200 V. Find its
(i) RMS value (ii) Average value (iii) Instantaneous value at t = 0.002 sec - Explain the working of a single phase energy meter with a neat diagram.
- a) Explain the working principle of a DC generator with a neat diagram.
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b) A 4-pole, lap-wound DC shunt generator has 720 conductors and flux per pole is 40 mWb. Calculate the EMF generated when running at 1000 rpm. - a) Explain the constructional details of a transformer.
b) A 200 kVA, 3300/400 V, 50 Hz single-phase transformer has 80 turns on the secondary winding. Assuming an ideal transformer, calculate
(i) Primary and secondary currents
(ii) The number of primary turns - a) Explain the working principle of a three-phase induction motor with a neat diagram.
b) A 6-pole, 50 Hz, 3-phase induction motor running on full load develops a useful torque of 150 Nm when the rotor EMF makes 120 complete cycles per minute. Calculate the rotor input power and mechanical power developed. - Explain the construction and working principle of an alternator with a neat diagram.
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