VFD Enclosures NEMA 3 or NEMA 4 rated enclosures

[airprep]

Hello Gentlemen,
I'm working on a DoD project in Romania, Deveselu, and need some help on a certain subject that has came up. We have a totaly enclosed and conditioned very large mechanical room and of course there are some motors and pumps controlled by VFD's, we have been posted a question as to what type of enclosures should be used in the mechanical room for the VFD's , NEMA 3 or NEMA 4 enclosures. As the area is conditioned and enclosed , I would expect that just a typical mounting apparatus could be applied in this scenario and nothing special would be needed but our client is requesting some more information. I am digging through code books and given our time difference it has been hard to get in contact with our supplier on the other side, any help would be great, thanks in advance.

[jraef]

Hello Gentlemen,
I'm working on a DoD project in Romania, Deveselu, and need some help on a certain subject that has came up. We have a totaly enclosed and conditioned very large mechanical room and of course there are some motors and pumps controlled by VFD's, we have been posted a question as to what type of enclosures should be used in the mechanical room for the VFD's , NEMA 3 or NEMA 4 enclosures. As the area is conditioned and enclosed , I would expect that just a typical mounting apparatus could be applied in this scenario and nothing special would be needed but our client is requesting some more information. I am digging through code books and given our time difference it has been hard to get in contact with our supplier on the other side, any help would be great, thanks in advance.

If you are still interested, this is sometimes an issue in mechanical rooms where there is a significant risk of water spray in the case of a broken pipe or flange seal, etc. In that case, the difference between Type 3 and Type 4 is somewhat moot, in that this is ONLY going to matter in a dire circumstances. Type 3 means that water is not specifically excluded from entering the enclosure, but will not collect in it and build up to any live components, meaning it's OK as long as it will drain out faster than it can get in. Type 4 means that NO water can enter. The problem with Type 4 and VFDs is that the VFDs need to cooled and the limits of cooling a VFD though isolated heat sinks will limit the HP size that can be used.

[airprep]

Yes that nails it on the head, we are dealing with some pressure drop issues in the MOV section of the CWP so the issue was drop from the top off the list, I actually mentioned that the nema 4 style enclosures would cause heat issues with the vfds, anyway great info ... thanks allot. ......