Which are the main differences between fixed speed and variable speed screw compressors?

Variable speed rotary screw compressors

Variable speed compressors work to maintain a constant air pressure, while the motor speed adjusts to meet the production air demand. Indeed, variable speed machines reduce engine speed aligning it with the actual air demand, saving energy.

Fixed speed rotary screw compressors

Unlike variable speed compressors, fixed speed compressors either run at 100% or are switched off. They are ideal in applications when the compressed air demand is constant. The machine will run at the same engine speed at all times, unless it is switched off. Fixed speed compressors always run at full speed and, therefore, they produce more air than required with a waste of energy.

The benefits of variable speed:

  • Low power consumption, since the variable speed air compressor adapts the engine power to the air demand
  • The initial investment for variable speed air compressors is offset by the lower energy consumption
  • When the variable speed screw compressor is operating at a lower power speed, it is quieter than a fixed speed machine
  • Constant pressure system. Besides, lower pressure reduces the risk of leakage
  • Longer components' life-cycle
  • Lower starting current when the motor begins to work
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