0)

b)

17 a)

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A ring shaped electromagnet has an air gap of 6mm and cross sectional area of
12 cm’. The mean length of the core (excluding air gap) is 60cm. Calculate the
mmf required to produce a flux density of 0.4 Wb/m? in the gap. Take the
relative permeability of the material as 400.
Derive the expression for energy stored in a magnetic field.
A balanced three phase load consists of three coils each having resistance of 4Q
and inductance 0.02H. It is connected to a 415%, 50112, 3-phase ac supply.
Determine the phase voltage, phase current, power factor and active power when
the loads are connected in (i) star (ii) delta
A 22017, 50Hz single phase sinusoidal voltage produces a current of 2.24 in a
purely inductive coil. Determine (i) inductive reactance of the coil (ii) inductance
(111) power absorbed (iv) expression for applied voltage and current.
With the help of circuit diagram and phasor diagram derive the relation between
line and phase voltages, and line and phase currents in a balanced delta
connected system.
Draw a neat schematic diagram of a Thermal power plant and explain its
operation.
Explain about any two types of available Non-conventional energy sources.
MODULE 5

Answer any one full question, each carries 10 marks.
Explain the construction and working of DC generator.
A four pole wave connected armature has 1000 conductors and flux per pole is
0.05wb. Calculate the emf generated when the generator is running at a speed of
1200rpm.
A 40 kVA transformer has a core loss of 450W and a full load copper loss of
850W. If the power factor of the load is 0.8, calculate (i) full load efficiency
(ii) maximum efficiency (iii) the load at which maximum efficiency occurs.

MODULE 6
Answer any one full question, each carries 10 marks.

Explain the constructional details of squirrel cage and slip ring induction motor
With suitable diagrams explain the principle of operation of a capacitor-start

induction motor. Compare it with split-phase motor. Give one application.

KE

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