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The VTAC 9 variable frequency drives offer horsepower ratings ranging from 1 to 200 Hp at 480V, and from 1 to 100 Hp at 208V. The drives feature an economizer mode allowing the drive to automatically adjust output voltage during changes in load conditions. The economizing feature minimizes current supplied to the motor for energy savings. A sleep/wake function allows the drives to be cycled off when the system demand drops below a preset level, and restart automatically when the demand increases.
The drives include an intelligent thermal management system that monitors drive temperature and can automatically change operating conditions to avoid drive shutdown during over-temperature conditions. In the event of a power-dip condition, the drive automatically decelerates into a regenerative mode for energy recovery to avoid a low DC bus fault. It then returns to the preset speed reference when AC line power returns to normal. 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.
A three-contactor bypass design features a drive test mode, enabling programming, troubleshooting and maintenance while operating in bypass mode. All modes can be controlled in either Hand (local) or Auto (network or terminal block) state. The bypass interface control board enables easy diagnostics and control via six visible status indicators. The design is rated for 100kA short circuit interrupting currents meeting the highest demands of local and national electrical codes.
The drives are available with an internally mounted communication interface, providing simple connectivity to building automation networks, including Johnson Controls Metasys N2, Siemens P1-FLN, Modbus RTU, LonWorks and BACnet. If system upgrades or changes in network communications are required, these communication modules can be easily added to existing installations.
A detachable five-line multilanguage LCD keypad is designed to simplify drives setup, control fault indication, diagnostics and metering. A Quick Start utility provides operators with a set of the most commonly programmed parameters. With Quick Start self-prompting screens, the drive can be quickly set up without in-depth knowledge of parameter structures.
A UL 508C plenum rating allows the drives to be mounted directly inside an air handling system, such as ventilation ductwork. A NEMA 3R design provides protection in outdoor environments against rain, sleet, snow and external ice formation. The drives and bypass packages also meet seismic requirements of the 2003 International Building Code as specified by AC156.
Content Category: HVAC