What is the difference between Fixed Speed and Variable Speed Drive Compressors?
Fixed Speed Compressors vs. Variable Speed Drive Compressors (VSD)
The basic difference between the two technologies can be found right in the name. Fixed speed compressors run at a continuous fixed speed and tend to be very efficient when operating at 100% of its capacity, meaning when the motor is running and compressed air is being manufactured. The inefficiency of a fixed speed compressor is very noticeable and can easily be measured when the unit unloads and stops making air. Before the motor comes to a complete stop, it will continue to run while no air is being produced, consequently wasting energy and money. Inefficiency and waste can especially be visible at facilities that operate multiple shifts and or have great flow demand fluctuation throughout the day.
Variable speed drive (VSD) technology works on a different principle, as it turns the motor at the appropriate speed in relation to the amount of air that is required within a given plant / facility. In simpler terms, as the need / demand for air increases, so does the speed of the motor, therefore supplying more flow / CFM. On the other hand, if the demand decreases, the motor will automatically slow down and only use the required energy to provide appropriate flow. VSD air compressors match the output to the demand that is needed and can sense how much flow is being used, while adjusting its speed accordingly. On slower production days, break throughout the day, or during second and third skeleton shifts, the VSD technology comes especially handy, as it eliminates the waste of electricity, therefore saving money.
Considering that compressed air usage is costly, as it accounts for over 70% of Total Cost of Ownership in electricity costs, utilizing VSD technology can help you achieve savings of 35-50%. Depending on size of the compressor, the savings can range from $100s to $10,000s annually or more, making it an ideal investment for any facility. VSD air compressors are becoming the norm rather than an exception, with many customer enjoying the annual energy savings and having the ability to reinvest the money into other assets.