These Power Packs provide 24VDC operating voltage to all WattStopper 24VDC occupancy sensors and daylighting controllers. Auxiliary relay Packs are similar to power packs, but only have an isolated relay and no transformer power supply.WattStopper Power and Auxiliary Relay Packs are designed to be flexible enough to control almost any lighting or HVAC load. For example, B347D-P Power Packs can control lighting circuits, self contained air conditioners, pumps, fans, motors, VAV systems, motorized damper controls and setback thermostats. They are excellent for any application which requires high voltage switchingthrough low voltage controls. By linking power packs and sensors, an almost unlimited number of configurations can be obtained.