Electric Motor Rpm Formula

1 ft lb f 1 356 nm.

Electric motor rpm formula. T ftlb p hp 5252 n 1b. Note that when an ac motor is loaded the spinning magnetic field in the stator does not change speed. Pulley and speed calculator. Per hp at 1200 rpm a motor develops a 4 5 lb ft.

The speed of the motor can be found by using speed measurement devices. 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. So for example if you have a 4 pole motor on 60 hz then rpm 60 2 4 60 1800 rpm. Motor torque changes with the speed.

T inlb torque in lb f. 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. Calculating the rpm resulting from a motor and speed reducer assembly requires only basic mathematical knowledge. For dc motor torque formula.

V input dc voltage. N revolution per minute rpm alternatively. At 1800 rpm a motor develops a 3 lb ft. Acthree phase induction motorrpmis determined by the formula.

For calculating torque for dc motor. Hz frequency or cycles sec. T inlb p hp 63025 n 1. P hp horsepower delivered by the electric motor hp.

Hence motor torque t p ω. Electrical motor power velocity and torque equations. 60hz is the most common frequency in the us. 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.

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. Rpm 120 frequency of poles in the motor. 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. 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.

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. At no load you have maximum speed and zero torque. Here omega ω is equal to 2 x pi x n rpm 60. T v x i 2 x pi x n rpm 60 n rpm is the speed of the motor.

T ftlb torque lb f ft. Torque in imperial units can be calculated as. I input dc current. Rpm shaft rotation speed or revolutions per minute.

Below is a small calculator that will solve the ratio for you. Check the circle next to the item you are solving for and enter the remain three items in the spaces provided. 50 x 60 x 2 6 000 no load rpm ã number of poles. For a 50 hz system the formula would be.