A 10-pole, three-phase, 50 Hz alternator has 180 slots. If the armature coils are short-pitched by two slots, what is the pitch factor?

Question

Question

This question was previously asked in

MPPGCL JE Electrical 28 April 2023 Shift 3 Official Paper

Answer 1

Concept

The pitch factor is given by:

\(K_p=cos({α \over 2})\)

where, K_P = Pitch factor

α = Short pitching angle

Calculation

Given, No. of slots = 180

Poles = 10

The armature coils are short-pitched by two slots. The angle contributed by one slot:

\(\theta={180\over slot/pole}\)

\(\theta={180\over 180/10}=10\)

The short pitched angle (α) = 2 × 10° = 20°

\(K_p=cos({20 \over 2})\)

K_P = cos (10)°