A DC shunt motor draws 13 amperes from a 250 volt supply. The armature resistance is 0,3 ohms and the field resistance is 120 ohms. Calculate the efficiency of the motor

Answer 1

To calculate the efficiency of the DC shunt motor, we first need to calculate the input power and the output power.

Input power (Pin) = VI
Pin = 250V * 13A
Pin = 3250 W

Output power (Pout) = V * I - I^2 * Ra
Pout = 250V * 13A - (13A)^2 * 0.3 ohms
Pout = 3250W - 42.9W
Pout = 3207.1W

Efficiency = (Output power/Input power) * 100%
Efficiency = (3207.1W / 3250W) * 100%
Efficiency ≈ 98.69%

Therefore, the efficiency of the motor is approximately 98.69%.