How much power must a 24-volt generator furnish to a system which contains the following loads? One motor (75% efficient) 1/5 hp; Three position lights 20 watts each; One heating element 5 amp; One anti-collision light 3 amp.

• A. 450 watts
• B. 385 watts
• C. 402 watts
• D. 500 watts

Answer: (A)

The main idea is to sum the electrical input power required by all loads, including the motor’s inefficiency, since the generator must supply that input power at 24 V.

Compute the motor’s input power: its mechanical output is 0.2 hp, which is 0.2 × 746 ≈ 149.2 W. With 75% efficiency, the electrical power needed by the motor is 149.2 / 0.75 ≈ 199 W.

Lights consume 3 × 20 W = 60 W.

Heating element uses P = V × I = 24 × 5 = 120 W.

Anti-collision light uses P = 24 × 3 = 72 W.

Total required power ≈ 199 + 60 + 120 + 72 = 451 W, which is about 450 W when rounded.

So a 24-volt generator rated around 450 W is appropriate.