torque and power calculation
torque and power calculation
(OP)
Dear friends..
i was trying to figure out the required torque(NM)and power of motor(HP)to rotate a cylinder, placed vertically on a turn table.
cylider OD=2 meter , ID=1.5 meter. weight of the cylinder is 7500 kg. required constant RPM = 0.1 . any help please..
i was trying to figure out the required torque(NM)and power of motor(HP)to rotate a cylinder, placed vertically on a turn table.
cylider OD=2 meter , ID=1.5 meter. weight of the cylinder is 7500 kg. required constant RPM = 0.1 . any help please..





RE: torque and power calculation
Like is it on frictionless bearings, is in just sitting on the table (not a turn table)(I miss read), then there is the coefficient of friction etc etc.
Turn table? Same deal. Is there a gear reduction unit? How much power is required to turn it.
RE: torque and power calculation
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RE: torque and power calculation
RE: torque and power calculation
t = WK2 x rpm
308 x T av.
T = WK2 x rpm
308 x t
WK2 = inertia in lb.ft.2
t = accelerating time in sec.
T = Av. accelerating torque lb.ft..
Inertia reflected to motor = Load Inertia * (Motor rpm/Load rpm)2
"Dear future generations: Please accept our apologies. We were rolling drunk on petroleum."
— Kilgore Trout (via Kurt Vonnegut)
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RE: torque and power calculation
First of all, if the friction force of the cylinder on the table is negligible then the induction motor will reach the no-load velocity [close to synchronous speed].
As jraef said, the start time does matter here.
We have to calculate the inertia moment of the cylinder.
J=mass*dia^2/8
mass=weight/g [kg] g=the gravity acceleration=9.807 m/sec^2.
mass=7500/9.807= 764.76 kg
So J=764.76*2^2/8= 382.38 Kg.m^2
Let's say the synchronous speed of the motor [for 50 Hz] will be 750 rpm.
The inertia moment "seen" from the motor [the reduction ratio 750/0.1=7500] will be
382.38/7500^2= 6.8/10^8 kg.m^2 [of course, negligible].
The friction will be negligible also. See:
http://www
Let's take a SKF thrust ball bearing of for 16000 N load and 100 rpm. The losses power will be 0.0117 w [negligible].If there is not other force acting on the cylinder as a load you have a motor working on no-load[could be any motor].
RE: torque and power calculation
"Dear future generations: Please accept our apologies. We were rolling drunk on petroleum."
— Kilgore Trout (via Kurt Vonnegut)
For the best use of Eng-Tips, please click here -> FAQ731-376: Eng-Tips.com Forum Policies
RE: torque and power calculation
"The God stays in the details".