AC Motors by RPM

AC Motors
RPM (revolutions per minute) is a rating for AC motors that represents the motor’s speed at the system frequency stated on the nameplate. RPM is indicated on the motor’s nameplate as required by NEMA regulations.

Shop 600 RPM Motors
Shop 900 RPM Motors
Shop 1000 RPM Motors
Shop 1200 RPM Motors
Shop 1500 RPM Motors
Shop 1745 RPM Motors
Shop 1800 RPM Motors
Shop 3000 RPM Motors
Shop 3600 RPM Motors

 

 

 

 

 

 

 


We offer a wide range of RPM options to meet your AC motor needs. In addition to knowing the RPM you need, there are additional factors to understand when looking at AC motors. .

Range of Options
- Our selection of AC motors ranges from 600 RPM to 3600 nameplate RPM.



What is RPM?

Revolutions per minute (or RPM) describes the motor’s shaft speed and is a product of the line frequency and the number of poles in the motor’s construction. The motor’s Nameplate RPM directly corresponds to the rated frequency also listed on the nameplate.

Example:
An 1800 RPM, 60Hz motor will rotate 1800 RPM @ 60Hz input line frequency. The same motor will turn approximately 900 RPM @ 30Hz input line frequency. For 3 phase motors, the various input line frequencies can be achieved using a Variable Frequency Drive (VFD).



RPM on the Nameplate


Determining RPM


VFDs and RPM


Variable Frequency Drives (VFDs, AC Drives) are used to control the speed of a 3-phase motor. They do this by altering the line frequency. Because RPM is a function of frequency and poles, changing the line frequency also changes the motor’s RPM. Half the frequency leads to half the RPM.
Example: A motor listed as 1800 RPM @ 60Hz on the nameplate can be reduced to 900 RPM with a VFD by changing the frequency to 30 Hz. Your motor must be inverter-rated, inverter duty, vector duty for use with a VFD.


Motors intended for use with a VFD will have a published motor turndown ratio. This is the lowest speed the motor should be run in relation to the nameplate RPM. Examples of turn down ratio ratings include but are not limited to: 2:1, 4:1, 12:1, 20:1 or even 1000:1 (vector duty).
Example: 20:1 Inverter rating means the motor can be safely operated at a 20:1 reduction of the nameplate RPM. Use equation above to determine lowest continuous operation speed for a 20:1 turn down ratio for an 1800 RPM motor.


HP and RPM

The horsepower listed on the motor’s nameplate is achieved at the Nameplate RPM. Horsepower and RPM share a linear relationship. An 1800 RPM motor operating at half speed will produce half the horsepower.

Used to change voltage and are suitable for a wide variety of applications.
  • Primary Voltage Options: 120V to 600V
  • Capacity Options: 50VA to 750kVA
  • Designed for 60Hz operation
  • Encapsulated and Ventilated options



Other Considerations
Voltage
Your chosen motor’s voltage should match the supply voltage available to you. Motors typically have more than one possible voltage depending on how they are wired.
Horsepower (HP)
Horsepower is a measure of the rate at which mechanical energy is expended and corresponds to the motor’s RPM. For your application, this means how much work is completed by the motor (such as how much material it can move and at what speed).
Frame
The size of the actual frame of a given frame size may vary slightly between manufacturers, but a frame size notation is a universal reference to shaft diameter, shaft length, and mounting footprint. Given motors from two different manufacturers with the same state frame size, those three dimensions will remain consistent.