Final answer:
The fuse size required for a 100HP DC motor at 220V with 90% efficiency is approximately 384.29 amps.
Step-by-step explanation:
The fuse size required for a 100HP DC motor at 220V with 90% efficiency can be calculated using the formula:
Fuse Size = (Power/ Voltage) * (1/Efficiency)
First, convert the power from horsepower to watts, where 1HP = 746 watts. So, the power of the motor is 100HP * 746 watts/HP = 74600 watts. Now, substitute the values into the formula to find the fuse size: Fuse Size = (74600 watts / 220V) * (1/0.90) = 384.29 amps. Therefore, the fuse size required for the motor is approximately 384.29 amps.