Answer:
The minimum current rating of the motor disconnecting means is 165 Amperes.
Explanation:
First convert the given power into units of watt. Since,
1 horsepower = 746 watts
Therefore,
40 horsepower = 40 x 746 watts
40 horsepower = 29840 watts
Since, we know that:
Power = Full Load Current (FLC) x Voltage
FLC = Power/Voltage
FLC = 29840 watts/208 volts
FLC = 143.46 Amperes
Now, the current for disconnecting means is at least 115% of the FLC, for the motors rated at 600 Volts or less.
Current for Disconnecting Means = (1.15)(143.46 A)
Current for Disconnecting Means = 165 Amperes
