Calculating Required Torque for Clutch Attachment to Electric Motor Shaft

What is the required torque rating for a clutch to be attached to an electric motor shaft running at 1150 rpm?

a. 0.22 Nm

b. 0.136 Nm

c. 0.34 Nm

The required torque rating for the clutch should be at least 0.136 Nm to ensure that the motor can drive the fan effectively.

When determining the required torque rating for a clutch to be attached to an electric motor shaft running at 1150 rpm, it is essential to consider the motor's power rating and the load it is driving. In this scenario, the motor is rated at 0.50 hp, which is equivalent to 373 watts. Assuming a typical efficiency of 80%, the motor can produce a maximum output torque of 0.22 Nm.

However, since the motor is driving a light fan, the torque requirement may be lower. To estimate the torque required to drive the fan, factors such as the fan's rotational speed and the size and shape of its blades need to be taken into account. Assuming the fan has four blades and rotates at 1000 rpm, with each blade having a length of 20 cm and a width of 5 cm, the force of air resistance on each blade can be calculated.

By considering a coefficient of drag (Cd) of 1 for a flat plate, the total force of air resistance on all four blades is determined to be 1.36 N. To convert this force into torque, it must be multiplied by the radius of the fan, resulting in a required torque of 0.136 Nm to effectively drive the fan.