Electric Motor Rpm Formula

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.

Electric motor rpm formula.

T ftlb torque lb f ft. Rpm 120 frequency of poles in the motor. I input dc current. For dc motor torque formula.

Torque in imperial units can be calculated as. Hence motor torque t p ω. The speed of the motor can be found by using speed measurement devices. Motor torque changes with the speed.

60hz is the most common frequency in the us. For a 50 hz system the formula would be. So for example if you have a 4 pole motor on 60 hz then rpm 60 2 4 60 1800 rpm. Poles number of poles of your motor.

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. Electrical motor power velocity and torque equations. 1 ft lb f 1 356 nm. 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 calculating torque for dc motor. 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. Acthree phase induction motorrpmis determined by the formula.

T v x i 2 x pi x n rpm 60 n rpm is the speed of the motor. 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. Check the circle next to the item you are solving for and enter the remain three items in the spaces provided. Per hp at 1200 rpm a motor develops a 4 5 lb ft.

Note that when an ac motor is loaded the spinning magnetic field in the stator does not change speed. Here omega ω is equal to 2 x pi x n rpm 60. At no load you have maximum speed and zero torque. At 1800 rpm a motor develops a 3 lb ft.

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. Rpm shaft rotation speed or revolutions per minute. Hz frequency or cycles sec. 50hz is the most common frequency outside the us.

Below is a small calculator that will solve the ratio for you. T inlb torque in lb f. N revolution per minute rpm alternatively. Pulley and speed calculator.

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. 50 x 60 x 2 6 000 no load rpm ã number of poles. 1750 rpm 1000 rpm 3 5 inches d 2 d 2 6 125 inches. T inlb p hp 63025 n 1.