Atlas Copco offers both VSD and fixed speed compressors because each type offers advantages in specific circumstances. For example, a fixed speed compressor is a smart choice when the demand for air is essentially constant. A factory running 24/7 with automated equipment that consumes compressed air at a predictable and uniform rate is a good application for a fixed-speed compressor. A VSD compressor is a smart choice when demand for air varies by process, time of day, shift or time of the year. When demand fluctuates, a VSD compressor that varies its speed is much more energy efficient than a fixed-speed compressor that can only run flat out. While vsd compressors cost more up front, they pay back the added investment through energy savings. The greater the variation in demand, the greater the potential savings. A VSD compressor can operate within a much tighter pressure band than a fixed-speed compressor can attain. A VSD compressor can operate at lower delivery pressures and still maintain the air system’s required minimum working pressure. VSD also delivers more consistent discharge pressure for all the compressed air applications throughout your facility. The net pressure on a VSD compressor can be set lower than the unloaded pressure on fixed speed compressor. Without no overpressure, each 1 bar results in 7 percent savings in energy.