VCC vs VSD (Variable Capacity Control vs Variable Speed Drive)

It’s a fact: in most cases the cost of electricity to run an air compressor continuously for one year is often greater than the initial purchase price of the unit its The Sullair Variable Capacity Control System (VCC), using its patented Spiral Valve system has unmatched full-load and part-load efficiencies that provide superior  power economy with a payback that is often less than two years.

On the variable capacity compressor, the compression volume (stroke), varies to suit the air demand by progressively opening or closing an internal by-pass port on the air end. This allows the compressor to actually reduce to as low as 37% of its rated capacity in a very efficient manner.

Compressor displacement is matched to the output required. The VCC technology assures precise operation for virtually all part load points. It provides significant power savings at these part-load conditions when compared to compressors that utilize suction throttling or load/no-load controls.

When the compressor is operating under a partial load the Spiral Valve only allows the compression for what the demand requires, thus increasing the efficiency of the compression process. The ultimate result is greater compression efficiency and reduced power consumption.

When compared to Variable Speed Drives offerings the VCC system offers long term low maintenance savings. Whereas the Variable Speed Drive with its electronic capacity controls offers significant savings in the first five years of its running life, but there is a large cost associated with maintaining the drive control unit. In the case of the VCC, it utilizes pneumatic controls which are not only more rugged but have proven to have a longer service life between repairs. Another interesting point is that should the drive unit on a variable speed drive unit ever fail, the compressor cannot be operated until it is either fixed or replaced. In the case of Variable capacity, if the Spiral Valve System ceases to operate properly, the compressor can still be operated until the Spiral Valve is fixed. As well, the cost of spiral valve repair/replacement versus Variable speed drive repair or replacement is night and day with the average repair kit for a spiral valve being less than 1/10th of the cost of a variable speed drive controller.

Useful Links

Sullube by Sullair (website)

Two-stage (also known as tandem) rotary screw air compressors (PDF)

Oil Free Products (PDF)

Sullair RFE series - 50 Hz Refrigerated Dryers (PDF)

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