Variable Speed Drive (VSD) Screw Compressors

Choose a variable speed air compressor for superior part-load performance

VSD/VFD

SFC15 air system

Many of Kaeser's rotary screw compressors are available with variable speed drive using Siemens drive technology. Kaeser's engineers have optimized the airend design to accommodate a wide flow range with unmatched efficiency. The drive motor and Sigma Profile airend operate at low speeds, resulting in exceptional reliability and long life.

Advantages of variable frequency drives

  • Meet varying loads:
    Most compressed air systems have varying loads and it is often more effective and efficient to apply multiple compressors to meet changing demand. In cases where the demand profile changes rapidly and frequently, variable frequency drive compressors may be recommended. By varying the frequency of the input electricity to the motor, these compressors speed up and down to match their air output to your demand.
  • Precise pressure control:
    Kaeser's SFC design includes highly accurate sensors to maintain stable pressure (± 1.5 psig), without wasting air by over-pressurizing the system. This also increases reliability and product quality in your plant.
  • Superior part-load performance:
    Kaeser's SFC units have superior part-load performance and make great trim machines. They can be easily integrated into a multi-compressor system to provide faster response to variations in air consumption. At the same time, they can reduce electricity costs since their electrical consumption varies directly with air production.
  • Soft start:
    Kaeser's frequency drives are the ultimate soft starter for your motor using the lowest start-up current. They eliminate heat spikes in motor windings, allowing unlimited motor starts. Of course, frequency drives usually have fewer starts/stops, which means less frequent loading and unloading, for less wear and tear on important mechanical parts.

10 to 30 hp variable speed compressors with belt drive: SFC 8 - 22S models

Model Rated Motor Power [hp] Min. Capacity [cfm] Max. Capacity [cfm]
SFC 8 10 12 48
SFC 11 15 21 71
SFC 15 20 27 95
SFC 18S 25 33 119
SFC 22S 30 33 141


Flows at 125 psig

25 to 700 hp variable speed rotary screw compressors with direct drive: SFC 18 - 515 models

Model Rated Motor Power [hp] Min. Capacity [cfm] Max. Capacity [cfm]
SFC 18 25 32 132
SFC 22 30 36 154
SFC 30S 40 37 176
SFC 30 40 49 208
SFC 37 50 54 248
SFC 45S 60 69 276
SFC 45 60 69 316
SFC 55 75 81 385
SFC 75S 100 102 478
SFC 75M 100 129 547
SFC 90M 125 136 641
SFC 110M 150 119 700
SFC 75 100 130 564
SFC 90 125 129 672
SFC 110 150 155 751
SFC 132S 175 198 885
SFC 132 200 198 951
SFC 160 250 242 1105
SFC 200 270 300 1257
SFC 250 340 370 1439
SFC 315S 350 370 1742
SFC 315 450 465 2057
SFC 410* 590 363 2537
SFC 515 700 412 3116


Flows at 125 psig
* Not available in 460V

60 to 450 hp variable speed compressors, oil-free: CSG 75 SFC - FSG 500-2 SFC models

Model Rated Motor Power [hp] Min. Capacity [cfm] Max. Capacity [cfm]
CSG 75 SFC 60 142 267
CSG 95 SFC 75 167 334
CSG 125 SFC 100 184 464
CSG 150 SFC 125 184 531
DSG 180-2 SFC 150 312 665
DSG 220-2 SFC 175 320 773
DSG 260-2 SFC 200 346 911
DSG 290-2 SFC 250 418 1058
FSG 420-2 SFC 350 604 1430
FSG 500-2 SFC 450 663 1710


Flows at 125 psig