New SFC 37 and 45S Variable Frequency Drive

SynRM synchronous reluctance motor boosts efficiency and service life

SFC 37 and SFC 45S screw compressors
New SFC 37 and SFC 45S models now with SynRM motors and IES2 classification.

Kaeser Compressors announces the new SFC 37 and SFC 45S. With the advanced SynRM motor-drive combination, these 50 and 60 hp units deliver flows from 54 to 275 cfm at 125 psig with superior part-load efficiency, longer service life, and reduced maintenance costs. The available pressure range is 80-217 psig.

Developed in partnership with Siemens and specifically designed to work with Kaeser’s SFC models, the SynRM motor-drive combination achieves top tier IES2 classification. This results in better specific performance, especially in the part-load conditions that call for variable speed compressors.

SynRM motors do not use aluminum, copper, or expensive rare earth metals in the rotors. Instead, they are made of electrical steel and feature a special profile. With this unique rotor design, the motors run cooler - resulting in lower bearing and winding temperatures and increased motor life. Because there are no magnets in the rotor, motor service is safer and easier.

To further enhance overall sustainability, SFC T models with the integrated refrigerated dryers have been upgraded with R-513A, a non-flammable, non-toxic advanced formulation refrigerant. R-513A has 56% lower global warming potential (GWP) compared to the current US standard (R-134a). This, combined with Kaeser’s advanced heat exchanger design, reduces refrigerant requirements without compromising dryer performance.

With these new additions, Kaeser has improved reliability and energy efficiency across its entire range of variable frequency drive units in the SFC 18-110S (25 - 150 hp) series.  For more information, visit or call (877) 417-3527 to be connected with your local authorized Kaeser representative.

04/23/20 , Free for publication, copy appreciated to

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SFC 37 and SFC 45S screw compressors

New SFC 37 and SFC 45S models now with SynRM motors and IES2 classification.

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SFC 37 screw compressor

SFC 37 with synchronous reluctance motor

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SFC 45S screw compressor

SFC 45S now with SynRM motor

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