- #1

SuperPat

- 4

- 4

I am Belgian and I have difficulty with english formulas.

I'm trying to calculate the power and torque required of a motor to rotate a load.

Here is the problem:

I have a motor (axis up) on which is fixed a cylindrical load of 15Kg. The diameter of this load is 400mm

Calculate the power and torque of the motor to reach a rotation of 15RPM in 2 seconds?

Here is how I calculated:

I calculate the inertia of my load: J = 1/2 m r²

J = 1/2 x 15 x 0.2 x 0.2 = 0.3 Kg.m²

Angular velocity: omega = (pi x RPM) / 30

omega = (3.14 x 15) / 30 = 1.57 rad/s

acceleration: a = omega / t

a = 1.57 / 2 = 0.785 rad/s²

torque: c = J x a

c = 0.3 x 0.785 = 0.24 Nm

Power : P = c x omega

P = 0.24 x 1.57 = 0.38 watts

I don't believe a 0.38w motor with 0.24Nm torque

can rotate a mass of 15Kg at 15 rpm in 2s

I've searched, but I can't find the error.

Thanks for your help.

Patrick