A lap-connected dc generator with 480 conductors has armature resistan...
Given Data:
- Lap-connected dc generator with 480 conductors has armature resistance of 0.06 Ω.
- When conductors are reconnected to form a wave winding, armature resistance becomes 0.54 Ω.
Calculations:
- In a lap winding, the number of parallel paths is equal to the number of poles.
- Let the number of poles in the original lap-connected dc generator be P.
- In lap winding, armature resistance (R) is given by: R = P^2 * ρ / A, where ρ is resistivity of the material and A is the cross-sectional area of the conductor.
- Given that R = 0.06 Ω, P = ? (let's assume P1).
- In a wave winding, the number of parallel paths is 2.
- In a wave winding, armature resistance (R') is given by: R' = 2^2 * ρ / A = 4 * ρ / A.
- Given that R' = 0.54 Ω.
- From the above equations: 4 * ρ / A = 0.54 Ω.
- Therefore, ρ / A = 0.135 Ω.
- Now, let's assume the number of poles in the wave winding is P2.
Solution:
- From the given data, we have:
- P1^2 * 0.135 = 0.06.
- P2^2 * 0.135 = 0.54.
- Solving the above equations, we get:
- P1^2 = 0.06 / 0.135 = 0.4444.
- P2^2 = 0.54 / 0.135 = 4.
- Therefore, the number of poles in the original lap-connected dc generator is √0.4444 ≈ 2.
- And the number of poles in the wave winding connected dc generator is √4 = 2.
Conclusion:
- The number of poles of the dc generator is 2 in the lap-connected configuration and 2 in the wave winding configuration. Hence, the correct answer is option 'C' (6 poles).
A lap-connected dc generator with 480 conductors has armature resistan...
Given that:
Number of conductors (Z) = 480
For lap winding armature resistance Ra
= 0.06 Ω When the generator is connected as lap winding then
(Parallel path = m.p and m = 1)
For Wave winding armature resistance Rwave = 0.54 Ω
When the generator is connected as wave winding.
In wave winding, the no. of parallel paths = A = 2
No. of conductors in each parallel path (A
P
) =
⇒
⇒ P2 = 36
⇒ Number of poles P = 6
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