Electric Motor Rpm Formula

60hz is the most common frequency in the us.

Electric motor rpm formula.

Ac 1 hp single phase ac motor has an input voltage of 230v the input current of 3 8 amps and working at 2500 rpm 0 8 pf 100 load. Output rpm formula input rpm times number of driving gear teeth divided by number of driven gear teeth. Rpm 120 frequency of poles in the 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.

Rpm shaft rotation speed or revolutions per minute. Hz frequency or cycles sec. Apply our formula 1. 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.

Note that when an ac motor is loaded the spinning magnetic field in the stator does not change speed. So for example if you have a 4 pole motor on 60 hz then rpm 60 2 4 60 1800 rpm. At 1800 rpm a motor develops a 3 lb ft. For a 50 hz system the formula would be.

Per hp at 1200 rpm a motor develops a 4 5 lb ft. A small transmission in a mixer has a 12 tooth gear on the motor shaft driving a 72 tooth gear on the mixer blade. 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. Acthree phase induction motorrpmis determined by the formula.

50hz is the most common frequency outside the us. The motor is turning at 1 800 rpm. Calculate the torque of the motor. Calculating the rpm resulting from a motor and speed reducer assembly requires only basic mathematical knowledge.

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. 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. 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.

Poles number of poles of your motor. Motor torque changes with the speed.