What is the total power drawn by a 24-volt system with the following loads: One motor (0.2 hp) at 75% efficiency, three 20-watt lights, a heating element drawing 5 A, and an anticollision light drawing 3 A?

What is the total power drawn by a 24-volt system with the following loads: One motor (0.2 hp) at 75% efficiency, three 20-watt lights, a heating element drawing 5 A, and an anticollision light drawing 3 A?

• A. 450 W
• B. 350 W
• C. 520 W
• D. 600 W

Answer: (A)

Total power in a 24-volt system is found by summing the electrical input power for each load. For the motor, a rating of 0.2 hp delivering that mechanical power with 75% efficiency means the electrical input is the mechanical output divided by efficiency. Convert horsepower to watts: 0.2 hp × 746 W/hp ≈ 149.2 W. Divide by 0.75 to get the electrical input: 149.2 W / 0.75 ≈ 199 W. The lights contribute 3 × 20 W = 60 W. The heating element draws 5 A at 24 V, so P = V × I = 24 × 5 = 120 W. The anticollision light draws 3 A at 24 V, so P = 24 × 3 = 72 W. Add them up: 199 W + 60 W + 120 W + 72 W ≈ 451 W, which rounds to about 450 W. So the total power drawn from the 24-volt system is about 450 W.

Total power in a 24-volt system is found by summing the electrical input power for each load.

For the motor, a rating of 0.2 hp delivering that mechanical power with 75% efficiency means the electrical input is the mechanical output divided by efficiency. Convert horsepower to watts: 0.2 hp × 746 W/hp ≈ 149.2 W. Divide by 0.75 to get the electrical input: 149.2 W / 0.75 ≈ 199 W.

The lights contribute 3 × 20 W = 60 W.

The heating element draws 5 A at 24 V, so P = V × I = 24 × 5 = 120 W.

The anticollision light draws 3 A at 24 V, so P = 24 × 3 = 72 W.

Add them up: 199 W + 60 W + 120 W + 72 W ≈ 451 W, which rounds to about 450 W.

So the total power drawn from the 24-volt system is about 450 W.