Motor Torque calculations
Motor Torque calculations is very easy for anyone if you know the basic idea and formula related to it.
The 3 factors that determine the type of work A motor can produce
1.speed
2.Torque
3.Horsepower
But here we will know about how to calculate Torque for motors.
Work:- Work is defined as Force applied over a distance but, In the case of Flywheel wenches and motors , The work is called Torque.
Torque :- Torque is a measure of how much a force acting on an object causes that object to rotate.
Or,
Torque is a rotating force produced or available at a motor’s crankshaft.
Simply,Torque is a special type of work that produces rotations.
Torque occurs when a Force acts on a radius
Torque = F×r , typical unit for measurements of Torque is N-m or pound feet.
Why ,I am saying Torque is a type of work.When you will see the unit of both you will understand.
So,to calculate Torque we need two things
1.Force Applied
2.Distance of force from centre of rotation.
Power :- Rate of doing work. Unit of power is watts (J/s) or horse power.
P = E/t
P = F·v
P = V·I
P = F.s ( For linear Motion )
P = τ·ω ( For Rotary Motion )
For Rotary motion, we are finding power so that it is easy for you to understand.
Power = (Force × Distance ) / Time
Power = [Force × Distance (Per Revolution) ] / Time ( in min. )
Distance per revolution = 2π × Radius
Distance per revolution per time = 2 π × Radius × RPM
We know that Torque = Force × Perpendicular Distance ( Radius )
Now, Force = Torque / Radius
As we know Power = [ Force × Distance (Per Revolution ) ] / Time (in min. )
Now,putting the value of force and Distance
We get, Power = {Torque/Radius} × { 2 π × Radius × RPM }
Finally, Power ( in Watt ) = Torque × 2π × RPM. Or,
Power (in watt ) = (Torque × 2π × RPS )/60
Now,we get
Torque = (Power × 60)/(2π ×Rps)
Or, (Power )/(2π ×Rpm)
Must read :- Calculating brake horsepower
This is the basic formula for calculations of Torque but only problem you face is unit conversion.
Note :-For calculations of Torque if motor you need to know power ( in watt or horsepower)
Now, I am writting directly formula with unit.
Torque in Imperial units can be calculated as
Tinlb = Php 63025 / n
where
Tinlb = torque (in lbf)
Php = horsepower delivered by the electric motor (hp)
n = revolution per minute (rpm)
Alternatively
Tftlb = Php 5252 / n
where
Tftlb = torque (lbf ft)
1 ft lbf = 1.356 Nm
Torque in SI units can be calculated as
TNm = PW 9.549 / n
where
TNm = torque (Nm)
PW = power (watts)
n = revolution per minute (rpm)
DC Motor Torque Calculations
the total torque developed of a DC machine is,
This torque equation of DC motor can be further simplified as:
Gear motor Torque calculations
Gear box output :- Multiply the gear ratio by the input torque
The torque unit is N.m (Newton · meters) or kilogram. meters (Kg · m).
Gear Reducer Torque = 9550 * Motor power / Rated Power motor’s input revolution*Ratio* gear reducer efficiency.
The above calculation is the torque equation.
Motor power = torque ÷ 9550 × Rated power‘s motor input speed /Ratio /service factor.
Here useful converted relationship to Output torque’s unit :
100 N.m = 885.07457 9349 Ibs in
100N.m = 885.07458 ibf.in
100 N/m = 0.5710147 ib/in
Servo motor Torque calculations
Torque Required By a Servo Motor = (Torque Due to Force of Gravity on Links and Payload) + (Torque Due to Angular Acceleration of Links and Payload)
This torque due to angular acceleration is calculated using the following equation:
τ = Iα
where I is the rotational inertia (or moment of inertia), and α is the angular acceleration around an axis.
Check Out Other Important Topics
Home IC Engine Electrical Important PDFs Boilers Synergy Maritime Exam Naval Arch Interview Questions Difference Between Types of Pumps Types of Valves MEO Class 4 Auxiliary Machines
