There is no doubt that the variable frequency drive is more expensive than fixed speed drive.VSD type air compressor and Fixed speed type air compressor are applied in any industry, such as sand blasting, chemistry, painting, etc. Why there are many customer want to purchase the Variable frequency drive? Because it can save more money in the long term. Now let me introduce differences of VSD type air compressor and Fixed speed type air compressor.

We call VSD type with VSD inverter as energy saving model if there is air consumption fluctuation from end user pneumatic machinery, here is one formula to calculate how many electricity power VFD rotary screw air compressor will save compared with fixed speed air compressor.

Rated motor power 45kw*30% unloading time*45% current loss during unloading time*total 4000 working hours/year=24300KW.H.

Explanation:

A. 30% unloading time. Unloading and loading is normal compressor working status. At loading status the compressor is generating compressed air, but at unloading status, air compressor is running but generating no compressed air, the working status is influenced by end user pneumatic machinery's air consumption, maybe sometimes 80% 0r 100% machinery is consuming the compressed air, but sometimes only 40% or 50% machine is consuming the compressed air, and sometimes it consumes no air compressed air

B. 45% current loss during unloading time. At unloading status compressor is running but generating no compressed air, at this moment the power is almost 45% of full loading status.