Centralized or Decentralized AC Drives

Over the last decade, there has been a significant increase in the number of industrial motors controlled by variable frequency drives, or VFDs as they are commonly referred to. VFD use greatly improves system performance, efficiency and flexibility on machinery, fans, pumps conveyors or other types of equipment, whether complex multi-motor networked control systems or simple standalone speed controls operating a single three phase AC motor. These systems and controls are typically enclosed in a panel and mounted on a wall or floor within the facility near the equipment they are operating.  When  upgrading existing machinery to improve efficiency or reduce bottlenecks, we also find that wall and floor space tends to be limited or reserved for future capacity expansion.

The centralized motor control enclosure is usually custom designed, engineered and built for the task at hand for both complex and simple speed control operations. The panel contains all necessary components to operate the system as intended. Cost to design, build, and install the centralized system is a significant factor in total system expenditure.

When simple standalone motor control is required, the decentralized option may be an option worth considering. Decentralized motor speed control consists of a VFD designed to be mounted on or near the machine with integrated operators providing the necessary functionality to operate the equipment. Start, stop, run, forward, reverse and a speed potentiometer are integral to the drive. In addition, an onboard disconnect switch is provided with lock out and tag out capability to safely remove power to the motor.  The decentralized drive enclosure by Transpower brand is rated IP66 NEMA4X indoor use. When using the decentralized option, significant space and cost can be reduced.  Drive foot print is considerably smaller than centralized systems due to its heat dissipating ability, while cost is reduced by eliminating the custom panel and the labor required to assemble the system.  Expensive wiring is also reduced, cutting labor and material cost.

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Mike Polo

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