Conveyor Motor Power Calculator

How is conveyor motor power found?

The motor driving a conveyor does two jobs. It lifts the load, and it overcomes the friction that resists the movement of belt, rollers and load. The sum of these resistances is the effective pull, and power is that force times belt speed: P = F × v.

Lift resistance is F_k = M × g × sin θ, where M is the mass of the load on the belt and θ is the slope. Friction resistance is proportional to the weight of everything that moves: F_s = f × (M + M_h) × g × cos θ. M_h is the mass of the belt and the rotating roller parts, and f is the resistance coefficient.

For bulk material the load on the belt follows from capacity: q = Q / v gives the load on one metre of belt.

Example

Take a belt carrying 100 tonnes per hour, 50 metres long, rising 5 metres and running at 1.5 m/s. It carries 18.5 kg per metre, 926 kg in total. Lift resistance is 908 N. With moving parts of 30 kg per metre and a resistance coefficient of 0.03, friction resistance is 710 N. Power at the pulley is (908 + 710) × 1.5 = 2.43 kW, and with a 90 percent drive efficiency the motor power is 2.70 kW.

You can check the lift power on its own: 27.8 kg/s × 9.81 × 5 m = 1.36 kW.

What does this leave out?

This is a preliminary calculation. You supply the resistance coefficient and the mass of moving parts, and the tool does not suggest values for them. The detailed methods in the standards add pulley, scraper, skirt and feed resistances one by one. A loaded start often decides the motor size. Make the final selection with the conveyor manufacturer's calculation and the applicable standard.