VFD in Class II Div 1 Area
VFD in Class II Div 1 Area
(OP)
Hello,
I have a design for which it has been requested that the VFD be placed near the equipment. The equipment area is class II, division 1, grain dust. NEC only says that the enclosures have to be dust tight, which I can achieve with a Nema 12 panel and filtering fans (also rated for 12). Is there are reason not to place the VFD in this area?
EE
I have a design for which it has been requested that the VFD be placed near the equipment. The equipment area is class II, division 1, grain dust. NEC only says that the enclosures have to be dust tight, which I can achieve with a Nema 12 panel and filtering fans (also rated for 12). Is there are reason not to place the VFD in this area?
EE





RE: VFD in Class II Div 1 Area
I would go with a single bottom vent and thermostatically controlled filtered air providing positive pressure to the enclosure. I'd include a temp switch to shutdown the drive if the enclosure temperature exceeded a normally expected temperature.
Keith Cress
kcress - http://www.flaminsystems.com
RE: VFD in Class II Div 1 Area
RE: VFD in Class II Div 1 Area
RE: VFD in Class II Div 1 Area
What size VFD are we discussing here? Smaller HP VFDs can be fully enclosed and in some cases, different mfrs offer a "fins out" or "flange mount" option wherein the VFD has the heat sinks designed to be shoved out of the back of the enclosure, no air exchange needed.
"You measure the size of the accomplishment by the obstacles you had to overcome to reach your goals" -- Booker T. Washington
RE: VFD in Class II Div 1 Area
RE: VFD in Class II Div 1 Area
Sorry about responding so late to your inquiry above, but I was away.
What is the size of this VFD? Is the VFD and motor supplied by the same Vendor?
I'm curious as to why anyone would 'requested that the VFD be placed near the equipment', especially if the location is classified. To me this sounds like this request originated from a Vendor who does not fully appreciate what he is requesting.
Is the requestor concerned about the cable length from the drive O/P to the motor? If so there are solutions for that (ie a dv/dt filter on the drive O/P).
Is there no space in the local electrical room to place this VFD?
I always try to avoid installing non-rated electrical in a classified area if at all possible.
It's been a few years (ie decades) since I have done any work in a Class 2 area, but in a Class 1 area, where I routinely work know, there is a requirement that the motor OEM state that the T-code for the motor will not exceed the AIT of the gas involved. A special CSA NP is required as well, on any VFD-driven motor installed in Class 1 area. I do not know if this is a requirement with your AHJ, but I would suggest that motor OEM be made aware of the fact that his motor will be located in a Class 2 area and be VFD driven. Even more so if the load is constant-torque.
Good luck, but I would push back on the requirement that the VFD be located in a classified area.
RE: VFD in Class II Div 1 Area
When you say " class II, division 1, grain dust" .
Then I assumed that it is a hazardous location ( Class II locations are those that are hazardous because of the presence of combustible dust. Note that the dust must be present in sufficient quantities for a fire or explosion hazard to exist. The fact that there is some combustible dust present does not mean a Class II hazardous location exists. To be considered a “dust”, the combustible material must exist as a finely divided solid of 420 microns (0.420 mm) or less. )
So if it is a hazardous location , then you fit in as shown below , in red color.
Had it been a Non Hazardous area then you fit in as shown below , in red color .
Since , we use IEC , thus I am more accustomed to "Zone System" instead of Class / division .
So if you think I am not correct , then please correct me , and help me to increase my knowledge.
Thanks
RE: VFD in Class II Div 1 Area
"You measure the size of the accomplishment by the obstacles you had to overcome to reach your goals" -- Booker T. Washington
RE: VFD in Class II Div 1 Area
RE: VFD in Class II Div 1 Area
RE: VFD in Class II Div 1 Area
RE: VFD in Class II Div 1 Area
There is no need to play each others advocate.
RE: VFD in Class II Div 1 Area
RE: VFD in Class II Div 1 Area
"You measure the size of the accomplishment by the obstacles you had to overcome to reach your goals" -- Booker T. Washington
RE: VFD in Class II Div 1 Area