How do I determine what size motor I need

[B110271]

Sorry for the non techie question here, just after some information and this forum seems to have the right brains to answer.

How do you determine the size/power of the motor required to perform the job.

As an example, say I wanted to fit an electric motor to move payload of say 1 ton, at speed to 15mph. Is there a basic way to determine this? I know I don't want the motor from a kids toy, but I also know i don't want to have a motor to launch a rocket...

Thanks for your help.

 

[BobM3]

You'll have to translate the load and linear speed to torque and RPM. Is this a 1 ton load on wheels that you want to have move at a velocity of 15 mph?

 

[jraef]

Start here. Engineer's Edge torque calculator for liner motion

Hint; You will need to determine the WK² (moment of inertia) of the load. There is a separate link on that page to calculate that if you don't already know.

Once you know the required load torque, then use that and the speed to get a rough determination of HP using;

HP = T (lb-ft) x RPM/5250

Then starting with that info and the WK² of the motor itself, make sure you can accelerate it fast enough for your needs using. If too slow, up the HP size and recalculate.

Sec. = WK² x speed change in RPM / 308 x AAT

Where;
AAT = Average Accelerating Torque

AAT = [(FLT + BDT)/2] + BDT + LRT / 3

Where;
BDT = Break Down Torque of the motor
FLT = Full Load Torque " " "
LRT = Locked Rotor Torque " " "

Or, go hire an engineer who already knows how to do this.