Question

A 20 kW, 200 V short shunt dc generator is supplying rated load at terminal voltage. The armature, series field winding and shunt field winding resistance are $0.02\Omega ,0,05\Omega and100\Omega$ respectively. Considering brush drop as 2 V, generated emf is______V.

• A. 209.041

Answer 1

The correct option is A 209.041


$\text{Rated load at rated terminal voltage,}$

$I_L=\frac{20000}{200}=100A$

$\text{Using dc generator equation,}$

$E=V+I_a{R}_a+I_L{R}_{se}+V_{BD}$

$E=I_a{R}_a+I_L{R}_{se}+V_{BD}+200$ ...(i)

$I_a=I_f+I_L$ ...(ii)

$I_f=\frac{200+I_L\times R_{se}}{100}$

$I_f=\frac{200+100\times 0.05}{100}$

$I_f=2.05A$

$\text{From equation (ii),}$

$I_a=2.05+100=102.05$

$\text{From equations (i),}$

$E_a=102.05\times 0.02+100\times 0.05+200+2$

$=209.041V$