Page 127 - Electrician - TT (Volume 2)
P. 127
ELECTRICIAN - CITS
where
B is the flux density in weber per square metre,
L is the length of the conductors in metres,
V is the velocity of the loop rotation in metres per second and
q is the angle at which the conductor cuts the line of force.
As sin q = 0
E at 0 position is equal to zero. As the loop turns in a clockwise direction at position 30° as shown in Fig 2c, the
loop cuts the lines of force and an emf is induced (E ) in the loop whose magnitude will be equal to BLV Sinq
30
where q is equal to 30°.
Applying the above formula, we find the emf induced in the loop at 90° position will be maximum as shown in
Fig 2c.
As the loop turns further towards 180° it is found the number of lines of force which are cut will be reduced to zero
value. If the quantity of emf induced at each position is marked by a point and a curve is drawn along the points,
the curve will be having a shape as shown in Fig 3b.
During the turn of the loop, from 0 to 180°, the slip ring S1 will be positive and S2 will be negative.
However, at 180° position, the loop moves parallel to the lines of force, and hence there is no cutting of flux by the
loop and there is no emf induced in the loop as shown in Fig 3b.
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CITS : Power - Electrician & Wireman - Lesson 76-85 CITS : Power - Electrician & Wireman - Lesson 76-85
