Comments on: Will a VSD compressor save me money?

By: Danny Gillis

Danny Gillis — Tue, 10 Apr 2018 19:56:07 +0000

There is a big difference in the compressor system. For example, with oil-injected compressors, the specific power is rather the same on different speeds.
At oil-free rotaries, the internal leakages are much higher if the speed is going down. I believe it’s difficult to save energy at any oil-free compressor with a VSD.
Don’t forget that their drive-line consumes about 5% more to the VSD (converting frequency & higher losses in the engine),
On reciprocating compressors you can efficient regulate with the inlet valves, The slow running piston compressors are also about 15% more efficient at full load.
Why make it difficult if you can count on reliable and sustainable technology?

By: Ron Marshall

Ron Marshall — Tue, 06 Feb 2018 15:15:53 +0000

Tony, I suspect you have problems with the words “usually less efficient”. That was my opinion too, until I started looking at the Compressed Air and Gas (CAGI) ratings of VSD compressors and comparing then to fixed speed units. Not all VSD compressors are less efficient than similar sized fixed speed units, for example, if you take a low cost single stage compressor and compare it with a premium brand unit, like a two stage unit, you might find the VSD beats the fixed speed even at full load. It always pays to check the specifications.

By: Mary Gannon

Mary Gannon — Tue, 06 Feb 2018 14:09:49 +0000

Hi Tony - I'm sure Ron would love a chance to discuss this with you - he can reply here or better yet, you can create an account at our forums and log your discussion there - he is one of our pneumatics moderators. https://forums.fluidpowerworld.com/.