The ability of engine-powered generators to start and supply standby power of acceptable frequency and voltage within 10 seconds of a utility outage has made these generators the standby power system of choice for a wide variety of facilities including mission critical.
Reactors for AC drives are available as either AC reactors or DC reactors (DC link chokes). Both serve the same main purpose: to smooth the current flow to the AC drive, and reduce damaging harmonics produced on the power line.
The available LEED credits and most obvious energy-saving possibilities are one thing. The potential for a ripple effect of system-wide savings by deploying VFDs as part of better overall monitoring are another.