A laboratory alternator is to supply rms at

PHYSICS · Subjective · CBSE · Physics · Electromagnetic Induction · Electromagnetic Induction

Problem

A laboratory alternator is to supply

110\,\text{V}

rms at

60\,\text{Hz}

. The available driving motor can maintain a steady speed of

1800\,\text{r.p.m.}

. The maximum magnetic flux density obtainable with the chosen core material is

0.30\,\text{T}

, and the rectangular armature slots restrict each turn to an effective area of

80\,\text{cm}^2

. (a) Show that, under these constraints, there is an upper limit to the turns per phase,

N_{\text{max}}

, beyond which the required rms voltage cannot be reached. (b) Determine this maximum permissible value of

N

. (c) If only

75\%

of the computed

N_{\text{max}}

is wound on the armature, find the rms voltage actually obtained at

1800\,\text{r.p.m.}

and state whether the design goal is met.