240V VFD substitute? 3

[TurbineGen]

I'm having a problem with a control system which requires speed control of 2 fans for coolers on a 25 MVA transformer. The fans are 5 hp and will be run at two frequencies: 45 hz and 60 HZ. The manufacturer has suggested using a VFD to achieve this. However, I really don't have the room in my control box. I'm already trying to fit 10 gallons into a 5 gallon bucket. Unfortunately I am unable to install and additional or larger control cabinet due to space constraints.

I was thinking of an saturable core reactor control or something to that effect. Does anyone forsee any problems with that? Are there any other possibilities?

I know it's seems ridiculous to run a cooler fan at reduced speed, but the reason for the dual speed is for noise limitations.

Any help or advice would be greatly appreciated.

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If it is broken, fix it. If it isn't broken, I'll soon fix that.

 

[TurbineGen]

Ozmosis, I'll definitely consider that.

Thank you all. You've been an incredible help.

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If it is broken, fix it. If it isn't broken, I'll soon fix that.

 

[sreid]

Good call, Ozmosis, I was not aware of the J1000.

TurbineGen, note that I chose a 10 HP model assuming you can drive the two motor/fans in parallel. Also I believe that the J1000 VFD does not require any air space on the sides of the VFD which also makes them more space efficient.