VFD heat dissipation 2

[ZDR1985]

Hi to all,
I am no electrical guy so I need your help.
We have pumps with 14MW motor power each (9 nos) and this are VFD controlled. How much would be the heat dissipation on the VFD controller for this size? Any rough estimate or calculation would be much appreciated. As I need to determine the cooling required for this.

Thanks!

 

[Power0020]

I understand you are after the heating load to get the HVAC requirements for electrical room.
to get the head dissipation, you should know the VFD losses from its datasheet, or (1-eta)*rated power ((~14 MW).

I guess a figure of eta around 98% should be a high level estimate but actual eta is best needed as it is a high power

if so, a heating load of 14*0.02 = 280 kW per VFD.

 

[ZDR1985]

Thanks Power0020 for that quick response. By the way, is motor power the same with the drive?

 

[dpc]

I'd guess a little lower than 98% efficiency, but with a 14 MW drive, the manufacturer should be able to give you accurate data specific to this installation. But also, many drives this size are water-cooled, so that will have a big impact on the amount of heat that is rejected into the surrounding space.

For a large drive like this, you need detailed engineering data for this specific drive - not something from an Internet forum.

 

[mikekilroy]

agree with dpc. one will need to know where the heat is going to properply mitigate it.

I think your saying I am no electrical guy so I need your help. says you have no business calculating this, if reason is more than just your idle curiousity.

http://www.KilroyWasHere<dot>com

 

[jraef]

I use 97% efficiency for calculating heat rejection for determining HVAC load. The efficiency is going to be lower at lower speeds, but at the same time so is the kW. So the worst case scenario is the VFD running at full speed, full kW output, 97% efficiency. There are a few brands that claim 98%, my personal belief is that this is marketing fluff, as in the Eff is 97.5% and responsible engineering types say use 97%, marketing people say it can be rounded up to 98%.

That said, if the VFD is going to include Line and/or Load reactors and/or sine wave filters and/or EMI/CE filters, all of those devices reject additional heat.



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