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Selection of Variable Frequency Drive (VFD)

asked Jun 28, 2016 in E&I by palagianomar (590 points) | edited Jun 28, 2016 by palagianomar
Hello, please educate me general aspect of a variable frequency drives (VFD)? Many thanks.

2 Answers

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answered Jun 30, 2016 by Kodi.Moretz (505 points)

The VFD should be located indoors in an unclassified area with ambient temperature range of 50°F to 104°F.  The VFD should have a minimum ingress protection of NEMA12 or IP21.

The VFD vendor should provide the minimum spacing required around the VFD essential to maintain proper ventilation and cooling, whether mounted alone in an enclosure, or as part of a multiple VFD installation within the same enclosure.

The VFD should be capable of withstanding the thermal and mechanical forces resulting from a short circuit.

An electrical by-pass should be provided.  The by-pass should be manually operated and provided with mechanical interlocks to prevent paralleling of the VFD and by-pass power supplies.

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answered Jul 6, 2016 by MattPalud (415 points)
VFD should be capable of 5 years run length between shutdowns.

VFD should operate over the entire operating speed range while motor is supplying rated torque.

The VFD should automatically ride through voltage dips of up to 20 percent lasting up to 0.5 seconds and automatically return (or re-accelerate) to set-point speed. VFD should be capable of automatically re-accelerating the driven equipment following voltage dips greater than 20 percent of rated in the input power supply, and up to 5 seconds duration, without the need to come to a complete stop.  Following the voltage dip or loss, the VFD should automatically re-accelerate when the input voltage has recovered to 90 percent or more of rated voltage.

VFD input protection should include incoming fuse and voltage protection features as required for overload, short circuit and ground fault, voltage transients, and be consistent with the power supply available short circuit.
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