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Adjustable Speed Drives, Part 2

Adjustable Speed Drives, Part 2Motors present power quality problems such as reduced power factor. So did the early variable frequency drives (VFDs). Why would you add a VFD to an already bad power situation?

Because, for most applications, manufacturers have solved the problems with the drive and with the motor. Today, you can specify a VFD that renders the motor and the drive essentially an impedance load to the power distribution system. They are power factor corrected and harmonics corrected. Power factor correction at the load reduces energy waste and improves equipment lifespan. PF capacitors at the service help the utility, but leave you with low PF at utilization equipment.

You don’t just buy a VFD, slap it in, and consider you’ve solved these problems. Your first step is to make sure you’re buying that VFD through a rock-solid electrical distributor who will help make sure you order the right one for your application. Typically, this means getting some basics from you such as the size and type of motor, the type of driven load (including the gearbox specs), and the nominal operating voltage. If you don’t have the motor, then you are usually ahead of the game by purchasing the motor and VFD as as matched set.

You want to do this work upfront, rather than late on a Saturday night when it finally becomes clear the drive you installed isn’t the right one for the application.

« Part 1 | Part 3 » | Source: Mark Lamendola | Mindconnection