torque required to stop a load

torque required to stop a load
			Engineering Forum

Posted by: Hitechelectomech ^®

12/26/2009, 01:15:33

Here is a question that i would like some advice on. I am an electrical engineer and i am selecting an electric motor that will use a 4Q VFD (regenerative drive) to control a load and i want to estimate how much torque (electric motor braking torque) is required to stop a moving load.

Electric motor driving a 12 inch winch or pulley. The gear ration is 9:1. The load attached to the line is hanging and will have the equivalant of 100 lbs of line pull against the winch. The load will be moving 50 feet per min.

How do I calculate the required torque that is seen on the winch to stop the load. I realize that this will depend on how quick i require it to stop. Let's use five seconds as an example.

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: torque required to stop a load

: torque required to stop a load -- Hitechelectomech Post Reply Top of thread Engineering Forum

Posted by: zekeman ^®

12/28/2009, 09:53:57

To stop a mass on winch moving at 50/60 ft/sec, 100lb in 5 seconds:
T=-I*@"
@'=W-T/I*t
w is initial angular velocity of output shaft, so when @' is 0
and t is 5 seconds the mass stops and the equation becomes
0=w-T/I*5;solve for T/I, the angular deceleration
T/I=w/5 and
T=w*I/5
I =m*r^2
m=100/32
r= radius of winch, ft
T = constant decelating torque at winch, lb-ft
@"= algebraic anglular acceleration (actually it decelerates) of winch
w= initial angular velocity of winch=V/r=50/60/r

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: torque required to stop a load
: torque required to stop a load -- Hitechelectomech	Post Reply	Top of thread	Engineering Forum