Electrical motor power velocity and torque equations.
Electric motor rpm formula.
Calculating the rpm resulting from a motor and speed reducer assembly requires only basic mathematical knowledge.
At 1800 rpm a motor develops a 3 lb ft.
Hence motor torque t p ω.
T inlb p hp 63025 n 1.
For dc motor torque formula.
Per hp at 575 volts a 3 phase motor draws 1 amp per hp at 460 volts a 3 phase motor draws 1 25 amp per hp at 230 volts a 3 phase motor draws 2 5 amp per hp at 230 volts a single phase motor draws 5 amp per hp.
Motor torque changes with the speed.
Acthree phase induction motorrpmis determined by the formula.
Poles number of poles of your motor.
1750 rpm 1000 rpm 3 5 inches d 2 d 2 6 125 inches.
In our example input electrical power of the motor is 0 22 a x 6 v 1 32 w output mechanical power is 1000 rpm x 2 x 3 14 x 0 00126 n m 60 0 132 w.
Using this formula you can see that a four pole motor operating on the bench under no load conditions runs at 1 800 rpm 7 200 ã 4 poles.
Dc controls adjust speed by varying the voltage sent to the motor this differs from ac motor controls which adjust the line frequency to the motor.
50 x 60 x 2 6 000 no load rpm ã number of poles.
N revolution per minute rpm alternatively.
P hp horsepower delivered by the electric motor hp.
Typical no load or synchronous speeds for an ac fractional horsepower motor are 1800 or 3600 rpm and 1000 5000 rpm for dc fractional hp motors.
Hz frequency or cycles sec.
At no load you have maximum speed and zero torque.
1 ft lb f 1 356 nm.
The speed of the motor can be found by using speed measurement devices.
Rpm shaft rotation speed or revolutions per minute.
For a 50 hz system the formula would be.
Below is a small calculator that will solve the ratio for you.
So for example if you have a 4 pole motor on 60 hz then rpm 60 2 4 60 1800 rpm.
Since the number of poles of athree phaseinduction motoris established when it is manufactured the only way to change the speed of the motor is to change thefrequency.
Here omega ω is equal to 2 x pi x n rpm 60.
Torque in imperial units can be calculated as.
Pulley and speed calculator.
I input dc current.
V input dc voltage.
T v x i 2 x pi x n rpm 60 n rpm is the speed of the motor.
T inlb torque in lb f.
Motors run at a specific revolutions per minute rpm and a speed reducer is needed if you want to keep that motor but have a lower rpm.
50hz is the most common frequency outside the us.
For calculating torque for dc motor.
T ftlb torque lb f ft.
Note that when an ac motor is loaded the spinning magnetic field in the stator does not change speed.
60hz is the most common frequency in the us.
T ftlb p hp 5252 n 1b.
