How Often Should You Start and Stop an Air Compressor Motor?

 

In industrial environments where compressed air demand fluctuates, it’s common to start and stop the air compressor motor based on process needs. While this is standard practice, excessive or unnecessary cycling can damage internal components, especially the motor windings, and reduce long-term system reliability. Understanding how often is too often is key to protecting your compressor investment.

 

Depending on the type of motor starter, motors can draw anywhere from 500 to 700% of the full-load amperage during acceleration. The motor windings experience a temperature rise due to this high in-rush amperage during start up. And keep in mind that the motor windings are subjected to this temperature rise during each motor start; therefore, an excessive number of motor starts can result in premature failure of the motor windings.

To minimize these risks, NEMA recommends limiting motor starts per hour based on design. To assist our compressor operators, FS-Elliott control systems provide protection from frequent starting of the motor. Our software allocates two starts within a 60-minute timeframe for the user to perform. If the compressor would need to be started for a third time within the 60-minute time frame, then a bypass would be required to override the safety feature. But doing so should be avoided as much as possible since these additional starts can wear on the machine over time.

 

Both starters and motors are heavily impacted by frequent starts and stops, so paying extra attention to these areas is important.  At FS-Elliott, we work to provide the best-in-class motors and starters with each of our Polaris^® and PAP Plus^® machines. However, if you select your own starter and motor, many factors should be considered. 

 

When sizing a starter for a compressor, it's important to consult an electrical engineer to check the location's power supply and understand the KWs needed to start the compressor. At FS-Elliott, we offer motors that are two-pole and typically run at 3600rpm, so they require slightly more power to start versus a slower four-pole, 1850rpm motor. 

 

Smart starters contain internal protection for how many times you can start your compressor per hour. This setting needs to be programmed in during the commissioning of your FS-Elliott compressor and is supplied in our technical manual under the motors and starters section. General starter types are listed below:

 

Numerous variations of motors can be installed within your air compressor. Every motor start raises the internal temperature of the windings, stators, and rotor inside the motor, regardless of your brand. Programming the time between the hot motor starts and stops per hour will allow the motor to cool down and reliably start again. Bypassing this option can lead to overheating of the parts within the motor, thus causing damage. This information is also included in our technical manual and should be checked during your compressor's commissioning and servicing.

 

Short cycling is a risk that operators take when turning an air compressor motor on and off too frequently. This creates inefficient energy spikes and increased thermal load, as motors draw much higher current at startup than during steady operation. Without time to dissipate heat, motor temperature compounds, leading to insulation breakdown and decreased lifespan. FS-Elliott control panels offer hot motor protection to prevent operators from dangerous frequent starts and stops.    

 

Although starting and stopping your compressor may sometimes be necessary, frequent cycling can significantly shorten motor life and reduce system reliability. Use manufacturer-recommended control settings, size your starter correctly, and rely on FS-Elliott’s built-in motor protections to ensure safe, efficient operation.

 

If you have any questions, please do not hesitate to contact your local FS-Elliott authorized channel partner to discuss your motor settings or any additional items on your FS-Elliott compressor.