VFD used with a condenser pumps 1

[maxgolder]

Dear Friends,

I wish control a condenser pump by a VFD, because the motor is oversized. 250 kw for the motor and 230 kw for the pump.
Also, we dont use the sensor there to maintain a constant flow and the valve is controlled manually.

Some engineers proposed me to program the VFD with a limited speed, so I mean that we integrated a minimum speed and a maximum speed to maintain a constant flow with a valve full open.

Please, someone can help me or propose me a good idea concerning this application.

Regards
maxximo

 

[MintJulep]

Why?

Assuming that this is an AC induction motor.

Motor ratings are maximum continuous.

Pumps too for that matter.


If you connect a pump that requires 230 kW input to a motor capable of producing 250 kW output then the motor will produce only 230 kW.

If you are controlling flow rate manually with a throttling valve then the pump will respond according to its pressure vs. flow characteristic, and the motor will happily follow.

My good idea is that the seems to be no reason at all to introduce a VFD into this arrangement.

 

[maxgolder]

Thank you for your answer,

Why?
I want use a VFD because if you check this company

http://www.astorlabs.com

They provide a smart vfd with a harmonic supression system included in the panel.

So, they explain me for example in the Grand hyatt in Beigijng, they installed 4 vfd for 4 condensers pumps(200 kw size) and they programed each VFD with a minimum and maximum speed, with this speed limitation, they can maintain a constant flow with a variable speed and save 25% up 30%.I dont know if the valve is controled manually or if the valve becomes full open or 60% open.

But I think, it is great if I save 25%.

 

[ScottyUK]

You can only save energy which is being wasted, and even then you can't save everything that is wasted. So first you need to establish what you are wasting and where, then you can make a meaningful decision whether a VFD is a worthwhile investment for your system.


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If we learn from our mistakes I'm getting a great education!

 

[Pumpsonly]

Another victim of typical VFD sales talk. You use VFD in condenser pumps not to maintain constant flow but to change the flow due to changes in load demand. You typically use VFD to maintain constant pressure.

See attached article for some explanation of VFD effect on the system hydraulic.