Question

A 6-pole, wave-wound armature has 600 conductors and is driven at 700 rpm. Determine the generated EMF in the armature if the flux per pole is 10 mWb.
1. 420 V
2. 230 V
3. 500 V
4. 210 V

Answer 1

Correct Answer - Option 4 : 210 V

Concept:

EMF equation of a DC Generator:

As the armature rotates, a voltage is generated in its coils, which is called Generated EMF or Armature EMF and is denoted by Eg.

\({E_g} = \frac{{ϕ ZNP}}{{60A}}\)

Where,

Eg = Generated EMF

P = Number of poles of the machine

ϕ = flux per pole in weber

Z = total number of armature conductors

N = speed of armature in revolution per minute (rpm)

A = number of parallel paths in the armature winding

Also,

A = P × m

Where,

m = multiplexity (simplex/duplex)

In wave winding, multiplexity is always 2 (two)

Therefore, A = 2

While in lap winding, there are two types:

1. Simplex Lap winding: m = 1

      ∴ A = P

2. Duplex Lap winding: m = 2 

      ∴ A = 2P

Calculation:

Given that,

Number poles P = 6

Conductors Z = 600

Speed N = 700 rpm

The flux per pole (ϕ) = 0.01 Wb

As winding is wave type 

Number of parallel paths A = 2

\(E_g = {(0.01)(600)(700)(6) \over 60(2)}\) = 210 V