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D1803 Pages: 3

Using Mesh Analysis determine the currents 1, 1) and 1; in the circuit shown in
figure.

A circular iron ring has a cross-sectional area of 0.01m? and a mean circumference
of 1.5m. A saw cut of 4mm wide is made in the ring. Calculate the magnetising
current required to produce a flux of 0.8mWb in the air gap if the ring is wound
with a coil of 175 turns. Assume relativepermeabilityof iron as 400 and leakage
factor as 1.25.

Define the terms flux, permeability and m.m.f with respect to magnetic circuits.
Find the form factor of the waveform shown in figure.

t
0 ) 4 6
A coil of resistance 8Q and inductance 0.03H is connected to an a.c supply of

240V, 50Hz. Calculate:

i) The current, power and power factor of the circuit.

ii) The value of capacitance which when connected in series with the above coil
causes no change in the value of current and power taken from the supply.

(4)

(6)

(3)

(3)
(5)

(5)

A non-inductive resistor of 10Q is connected in series with a choke coil having (10)

internalresistance of 1.2Q and is fed from a 200V, 50 Hz supply. Current flowing
through the circuit is 8A. Calculate:

i) Inductance of the choke coil ii) Voltage across the choke coil

iti) Power absorbed by the choke coil iv) Power absorbed by non-inductive
resistor v) Total power absorbed. vi) Phasor diagram of the voltages in the

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