Correct Answer - Option 3 : 80 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.
\({E_g} = \frac{{\phi ZNP}}{{60A}}\)
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 (r.p.m)
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:
- Simplex Lap winding: m = 1
∴ A = P
- Duplex Lap winding: m = 2
∴ A = 2P
NOTE:
If multiplexity is not mentioned, then always take simplex lap winding i.e. m = 1
Application:
P = 4
Z = 800
ϕ = 10 mWb = 10 × 10-3 Wb
N = 600 rpm
A = P = 4
\({E_g} = \frac{{\phi ZNP}}{{60A}} = \frac{{10 \times 10^{-3}\;\times \;800\; \times\;600\; \times \;4}}{{60\;\times\;4}}=80\;V\)
∴ The EMF generated is 80 V.