VFD drives in a C1D2 area

[D!NNy]

My project has a couple of VFDs that are located in the C1D2 area as shown in the picture.

we want to explore all the options available to get these drives rated to be operated in the C1D2 area:

i. Moving the drives out of c1d2 is not possible
ii. Installing a purge system is not possible for the size drives we have (500kVA, 600kVA and 1200kVA toshiba drives)
iii. installing a new building around these drives. I am evaluating two options.
Option 1: Installing a enclosed building, adequately ventilated and move drives into it. And make sure building is vapor tight for the C1D2 radius only.
Option 2: Install a barrier vaportight similar to option 1 but it is not an enclosed building.

My question is as per API 500 provided a building adequately ventilated and vapor tight portion is a straight forward solution (option 1) , but instead of placing a enclosed building, why not put a barrier that is vapour tight for the C1D2 area (option 2) which is cheaper and easy to build?

How a adequately ventilated building is different to have a barrier ? see attached picture.

Thanks for the help in advance.

 

[rbalex]

Option 2 is fine. Just make sure that it cuts the entire classified envelope. That is, make sure that there is no 18 or 24” high classified envelope that commonly extends from the source beyond the edges of the barrier. See API RP 500, Figure 30 for example. Another option if an extended envelope exists is to raise the equipment above it.

 

[kwired]

I agree with Bob. You are essentially eliminating the classified location with whatever you build, may be some details involved in assuring you actually eliminated the need for classification in that particular space.

An advantage of a room instead of a smaller hazardous location rated enclosure is some enclosures can be quite expensive and you possibly get more bang for your buck if you have additional items that may need to be separated from the hazardous location and could be located in that room (now or down the road).

 

[Besoeker]

DINNy

One of the fairly critical aspects, as you are probably aware, is adequate cooling if the VFDs are to be located in a sealed building or enclosure, that can be a challenge. Especially with these quite big drives. I usually allowed for 2.5% losses.

We supplied some VFDs for use in coal mines also quite large. These were mounted in a finned cast iron enclosure which were generally described as explosion proof but actually they would let hot gasses escape if the pressure was great enough. The technique was to make the flanges on the enclosures wide enough to sufficiently cool the hot gasses.

 

[kwired]

DINNy

One of the fairly critical aspects, as you are probably aware, is adequate cooling if the VFDs are to be located in a sealed building or enclosure, that can be a challenge. Especially with these quite big drives. I usually allowed for 2.5% losses.

We supplied some VFDs for use in coal mines also quite large. These were mounted in a finned cast iron enclosure which were generally described as explosion proof but actually they would let hot gasses escape if the pressure was great enough. The technique was to make the flanges on the enclosures wide enough to sufficiently cool the hot gasses.

With the "room" concept one could have multiple units in the room instead of more limited space in an enclosure rated for the environment, then either duct fresh air into the room, install a HVAC system or both to handle excess heat.

 

[petersonra]

My project has a couple of VFDs that are located in the C1D2 area as shown in the picture.

we want to explore all the options available to get these drives rated to be operated in the C1D2 area:

i. Moving the drives out of c1d2 is not possible
ii. Installing a purge system is not possible for the size drives we have (500kVA, 600kVA and 1200kVA toshiba drives)

Not possible? All kinds of things are inconvenient but that does not make them impossible.

I sort of like the idea of just building a wall that cuts into the D2 area. From what you are saying I kind of envision some visqueen stapled to some studs ("barrier vaportight"). I would want something a little more substantial. I saw something similar once that was made from sheet metal roof panels. It looked pretty substantial and inexpensive as well. In that case it was to control splatter.

 

[Besoeker]

With the "room" concept one could have multiple units in the room instead of more limited space in an enclosure rated for the environment, then either duct fresh air into the room, install a HVAC system or both to handle excess heat.

Actually these enclosures were custom built, pretty large and had much kit in them than just the VSDs.
The VSDs themselves were sizable, up to 1,000 kW and 3.3 kV.

 

[kwired]

Actually these enclosures were custom built, pretty large and had much kit in them than just the VSDs.
The VSDs themselves were sizable, up to 1,000 kW and 3.3 kV.

I suppose one could have some sort of modular system that is somewhat able to be customized with optional components, or you have totally custom built that can be anything you want it to be.

Difference between them rating wise may be listing vs code governing the design of them.

 

[drktmplr12]

DINNy

One of the fairly critical aspects, as you are probably aware, is adequate cooling if the VFDs are to be located in a sealed building or enclosure, that can be a challenge. Especially with these quite big drives. I usually allowed for 2.5% losses.

about 16 tons required to dissipate the heat of those drives, not including any external factors such as ambient temperature or other thermal radiation sources.

forcing that much air through a small room might make it a wind tunnel

 

[kwired]

about 16 tons required to dissipate the heat of those drives, not including any external factors such as ambient temperature or other thermal radiation sources.

forcing that much air through a small room might make it a wind tunnel

You have same problem in a small room even if not built to get out of a classified area.

 

[D!NNy]

Option 2 is fine. Just make sure that it cuts the entire classified envelope. That is, make sure that there is no 18 or 24” high classified envelope that commonly extends from the source beyond the edges of the barrier. See API RP 500, Figure 30 for example. Another option if an extended envelope exists is to raise the equipment above it.

Much thanks for the response i was thinking in the same lines
But i missed the article Figure 30.

 

[D!NNy]

I agree with Bob. You are essentially eliminating the classified location with whatever you build, may be some details involved in assuring you actually eliminated the need for classification in that particular space.

An advantage of a room instead of a smaller hazardous location rated enclosure is some enclosures can be quite expensive and you possibly get more bang for your buck if you have additional items that may need to be separated from the hazardous location and could be located in that room (now or down the road).

Much thanks for the response.
Since few different locations on the platform, which makes the enclosed building even more harder, so barrier is a much better way to pursue.

 

[D!NNy]

DINNy

One of the fairly critical aspects, as you are probably aware, is adequate cooling if the VFDs are to be located in a sealed building or enclosure, that can be a challenge. Especially with these quite big drives. I usually allowed for 2.5% losses.

We supplied some VFDs for use in coal mines also quite large. These were mounted in a finned cast iron enclosure which were generally described as explosion proof but actually they would let hot gasses escape if the pressure was great enough. The technique was to make the flanges on the enclosures wide enough to sufficiently cool the hot gasses.

Thanks for the input, i understood this part, if we were going to put a enclosed building we were either going to specify a C1D2 rated AC or regular ac to be located in the unclassified area.