VFD heat dissippation

[HamidEle]

I am working with VFD. The heat loss from VFD is 200KW.plus other heat loss. The total heat loss is about 230Kw. Does it mean the HVAC has to sized to be larger than 230Kw?

Thanks

 

[dpc]

It depends on what the HVAC system is supposed to do and what you mean by "sized larger than 230 kW" . Not enough data. As the EE, one would generally provide the heat loss data to the HVAC engineer and then let them design the HVAC system.

 

[sreid]

Is the VFD output power 200kW and the input power 230 kW?

 

[CJCPE]

If you have a VFD losses of 200kW including motor losses, the motor must be rated about 2500kW (3300 Hp), twice that it the 200kW is the losses for the VFD alone. Is that what you are asking about?

 

[itsmoked]

That! is a lot of loss.

I would think you save a bundle by just turning the air over instead of mechanically moving the heat. Yuck.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[HamidEle]

VFD is 3500HP. As a matter of fact, electrical power for HVAC won't be that much. I asked one of my friends, who is HVAC engineer, to size the HVAC. It turned out to be only 50kW, considering the building size and room temperature diferences.

 

[motorspert]

Hamid
8% losses in the VFD alone? That seems a poor dive efficiency to me. In fact, even if it included the motor losses I think it would be a lot. Is that the data from the manufacturer? Is the drive system continuously running?

 

[jraef]

A lot of MV drives now are 18 or 24 pulse so they have phase shifting transformers built-in. A lot of those losses are in the transformers.

 

[itsmoked]

Hey Jeff are these transformers 'real' isolation transformers? Or are they just 'I's? Are they strange in any way?

I am having a problem picturing a truckload of transformers gathered around some relatively small VFD.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[dpc]

Keith,

The one's I've seen use one special multi-winding transformer with multiple secondary windings.

 

[itsmoked]

Thanks dpc. That makes more sense to me now.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[jraef]

Lots of other stuff here, but scroll down to Figure 3 for a graphical representation.

Phase shifting transformer paper

And then to see how this translates to the real world of MV drives, go to page 9 of this brochure.
Robicon perfect harmony drive brochure

PS: They are not exactly "little" drives we are talking about here.

 

[itsmoked]

Most illuminating Jeff. Thanks.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com