178B3300 by Danfoss

The 178B3300 is an AC variable-frequency drive produced by Danfoss and used in the VLT 6000 HVAC Drives series. As a stand-alone controller, it modulates the speed of three-phase induction motors used in supply fans, return fans, pumps, and other ventilation equipment. This allows building automation systems to match airflow or water flow to real-time demand while reducing energy use and mechanical stress. In typical air-handling systems, changing motor speed instead of repeatedly cycling motors on and off can help maintain steadier operating conditions and quieter performance.

Its sealed housing has a Compact IP54 rating, which helps protect the drive from dust and water splashes without requiring an added cabinet in many indoor installations. The power section accepts three-phase mains from 380-460 VAC, so it can connect directly to common commercial distribution panels. A front-mounted control panel is included with an LCP, giving the operator local access to start, stop, and parameter navigation functions through a two-line display. Internally, the controller is delivered as a standard unit, so it does not use special heat-sink extenders or reinforced components. The printed circuit boards come with no coating, which makes the unit better suited to clean electrical rooms with controlled humidity and limited airborne contamination.

The drive is supplied with no options in the application slot and no fieldbus card, so remote commands are handled through hardwired terminals instead of a network connection. It is also shipped without an RFI filter, so any needed electromagnetic interference suppression must be added externally. That layout suits installations where start, stop, speed reference, and status signals are exchanged through discrete building-control wiring. The control package is focused on basic speed control for standard ventilation and pump duties where advanced expansion features are not required.