Question

24-slot, 2-pole, lap-would dc machine has 18 turns per coil. The average flux density per pole is 1 Tesla. The effective length of the machine is 20 cm and the radius of the armature is 10 cm. The magnetic poles cover 80% of the armature periphery. For armature angular velocity (ω_m) of 183.2 rad/sec, the induced emf in the armature winding is nearly
1. 585 V
2. 1050 V
3. 1260 V
4. 1465 V

Answer 1

Correct Answer - Option 3 : 1260 V

Slots = 24

Poles = 2

Number of parallel paths, A = P = 2 (lap winding)

Number of conductors (Z) = 24 × 18 × 2 = 864

Effective area = πRℓ × η

= π 0.1 × 0.2 × 0.8

Effective area = 0.05 m²

∴ ϕ = B A

ϕ = 1 × 0.05 = 0.05 wb

\(E = \frac{{P\phi ZN}}{{60A}} = \frac{{2 \times 0.05 \times 864}}{{60 \times 2}} \times \frac{{60 \times 183.2}}{{2\pi }}\)

E = 1259.59 ≈ 1260 V