Product Description:

The 178B7799 is an AC variable-frequency drive manufactured by Danfoss as part of the VLT 6000 HVAC Drives series. It is used in building automation air-handling systems to regulate the speed of three-phase induction motors that move conditioned air. By varying motor frequency instead of relying on mechanical dampers, the drive lowers electrical demand and soft-starts fans, which reduces mechanical stress and energy consumption. This method also helps match airflow to changing demand instead of running the motor at full speed continuously. It can therefore support smoother motor operation during startup and speed changes.

Its input window of 380-460 VAC allows direct connection to common 400 V and 460 V distributions without external transformers. The unit supplies up to 1.5/2.0 kW/HP, which suits small supply or exhaust fans in zone boxes and terminal units. A compact NEMA 1 enclosure shields internal parts from incidental contact and settled dust while keeping the footprint suitable for panel mounting. Local interaction is provided through a Local Control Panel (LCP), so operators can start, stop, and adjust setpoints at the drive without a remote workstation. To limit conducted emissions, an integrated Class A1 and B filter suppresses high-frequency switching noise for industrial and commercial environments.

The electronics are supplied in a standard unit configuration for general HVAC duty. The circuit boards have no protective coating, so the drive should be installed away from corrosive gases or heavy condensation. The unit is supplied without communication options, so control is handled through analog inputs and relay logic. That arrangement suits applications that rely on simple hardwired control rather than networked fieldbus communication. In Danfoss selection software, this model is identified as Graham.