The Variable speed compressors are being promoted as the best solution to energy savings on your compressor ! Is that really true ?

 Although I have been working on developing the variable speed drive myself, I must admit that it reduces the energy loss rather than save energy !

 How comes ? 

 When the energy at unload or off-load for a volumetric compressor is high (>30% of full power), you can of course save energy by speeding down and avoid unload. This is the reduction of the losses during the unload period.

 Additional losses by speeding down of the compressor air-end, risks of break-down of electronics and energy losses in the power electronics are introduced.

The compressor block has only one optimal operating point, the efficiency when changing the speed declines.

The electronics of the Frequency converter consumes 5-10% of the total power during the whole running cycle.   

And the lifetime of power electronics is not that long. The savings you have made can be lost to repair.