PowerFlex 400 HVAC AC Drives Expand Commercial Application Opportunities


To help HVAC contractors and engineers efficiently apply variable frequency motor control to a broader set of motor-driven applications, Rockwell Automation has expanded its Allen-Bradley PowerFlex 400 HVAC drives offering to include increased power ratings up to 350 horsepower. Optimized for commercial fan and pump applications, PowerFlex 400 AC drives feature built-in network connectivity for seamless integration into building automation systems, as well as flexible packaging options for easy installation and startup. “Applications involving large centrifugal loads and changing flow rates, such as air handlers, cooling towers and chillers, are prime targets for significant energy savings,” said David Mantey, product marketing manager, Rockwell Automation. “PowerFlex 400 variable frequency drives deliver optimum speed control to help users improve air handling efficiency, optimize energy consumption and reduce overall energy costs.” Ease of Integration. An integral RS485 communications interface provides support for most standard building automation networks, including Modbus RTU, N2 and Siemens P1-FLN. These protocols are parameter selectable and require no additional hardware or software. For expanded communication capability, optional add-on modules provide connectivity to LonWorks and BACnet networks. Built-In Intelligence. PowerFlex 400 HVAC drives feature an embedded PID controller that automatically adjusts the output frequency to maintain a process variable. Three programmable skip frequencies and bands prevent the drive from running continuously at resonant speeds, which could cause mechanical breakdowns. Selectable fan and pump curves provide reduced voltage patterns for centrifugal fan and pump loads. A sleep function allows the drives to be cycled off when the system demand drops below a preset level, and restarted automatically when the demand increases. For applications that require unattended operation, a “Start At Power Up” function allows the drives to resume running once power is restored after a power outage. Users also can connect the drives to fire and safety systems via freeze/fire and purge inputs. Disconnect and contactor bypass packages simplify installation and startup by combining operator interface, control, communications and power options in preconfigured assemblies. Contactor bypass packages come with three contactors, allowing drive test functionality and drive isolation when in bypass mode. Users can easily program, monitor and control the drives using Allen-Bradley DriveExplorer and DriveTools SP software. A UL 508C plenum rating gives PowerFlex 400 drives further installation flexibility by allowing them to be mounted directly inside an air handling system, such as ventilation ductwork. The drives also meet seismic requirements of the 2003 International Building Code as specified by AC156. NEMA/UL packaging options include enclosures to meet both indoor and outdoor application requirements.
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