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Where to place VFD's best

Where to place VFD's best

Where to place VFD's best

We regulary install industrial fluid treatment systems with normally 3 VFD controlled pumps. Until now the VFD's have been placed in the PLC's electrical enclosure. Unfortunatly this often causes space problems inside the enclosure since the VFD's are really big serving pumps up to 90 kW.

A solution would be placing the VFD's outside the enclosure in front of the pumps, but we don't have any experience doing that and fear that this could compromise the VFD's reliablity and life span. In this context I have some question someone can hopefully help:

- which provisions have to made if VFD's are installed outside of the main electrical enclosure?
- are there limitiation regarding ambient temperature, humidity, oil dust or dust in general?
- are there VFD's types which are more convenient for this kind of installation than others (we normally use SIEMENS VFD's)?

RE: Where to place VFD's best

The only requirements I'm aware of are that the results have to be completely finger-safe.

You must mount them with the clearances they describe in every VFD manual ever written.

They must be environment proof. Outdoor ones have lots of restrictions, the sun can not land directly on them. Rain etc.

Is there a possibility a pump seal failure could hose the drive? Not allowable!

VFDs prefer to be closer to the motor they drive.

You want things labeled very clearly as to how you de-power the VFD.

You must have the drive oriented correctly, up/down.

OF course, there are limitations on the surrounding ambient conditions! Read them in the manual as that is a good check-list. Dusts, sprays, high temps, really low temps, will all be a problem. Often a drive mounted in an enclosure can have heat stroke if the enclosure is not force cooled. The fan or filter clogging can destroy the drives.

The wall-mounted drives take into account the finger-proof issues. Some drives while built finger proof are not really and should not be used since they leave a little bare wire touchable at the lugs. Make sure the drives have some plastic depth protection around line voltage connections.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Where to place VFD's best

Ok thanks a lot

RE: Where to place VFD's best

In IEC-land I'd recommend to consider the codes for ingress protection, where the numbers give information on protection against touching and dust as well as protection against water.

Within a cabinet usually IP23 is common, outside a cabinet (but within a building) IP54 or IP65. Detailed requirements of course depending on industry.

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