Question

A 200 V shunt motor takes 10 A when running on no load. At higher loads the brush drop is 2 V and at light loads it is negligible. The stray load loss at a line current of 100 A is 50% of no load loss. If armature and field resistance is 0.2 $\Omega$ and 100 $\Omega$ respectively, then the power loss in the motor is ____kW

• A. 5.1

Answer 1

The correct option is A 5.1
$\text{No load loss = 200 x 10 = 2000 W}$

$I_f=\frac{200}{100}=2A$

$\text{Core loss}=(200\times 8)+(8^2\times 0.2)$

$=1587.2W$



$\text{At load :}$
$\text{Stray load loss = 0.5 x 2000 = 1000 W}$


$P_L=(I_a^2{R}_a+V_{brush}{I}_a+P_{stray})+(P_{core}+P_{shuntfield})$

$P_L=({98}^2\times 0.2)+(2\times 98)+1000+1587.2+(200\times 2)$

$P_L=5.104kW$