Dear
I am modelling a water distrubution system. The pump station is composed of 3 pumps and equipped with a variable speed. The pump curves at different speeds are the following:
Usually the pump is define by one curve using "pump definitions". My question is can I insert the 4 curves in one pump/pump station.
Thank you
There is no need to add curves. The curves are automatically adjusted as speed changes.
Thank you for your feed back
As I mentioned, in the software I can insert only one pump curve.So I inserted the lowest curve with 9 1/2" to the model
In low demand scenario, the operating point is (1600 GPM, 82 feet), the pump curve would be the lower curve with 9 1/2". the model runs smoothly without any error message
When the demand increases, the operating point is (3100 GPM, 140 feet), hence the pump curve would be the lower curve with 12 1/2". The model shows an error message stating that "pump station ca't deliver flow".
Hence I asked if there is a possibilty to insert the above curves at one pumping station and the model detects the suitable curve for each demand (high/low).
Adjustments to the pump curve based on speed and those based on impeller size are two entirely different things. The impeller size is essentially fixed once you install the pump. It doesn't change in real time. The speed can change continuously.
Determine what the actual impeller size is and use that.
Thank you for your explanation.
A pump with a fixed impeller diameter, can have different operating points depending on the speed.
So a pump equipped with a VFD, can have different curves, each curve is associated with a speed (rpm).
the different curves and operating points can be derived from the affinity law.
So my question is : can I insert the different curves (@ specific speed) in my model ?
You mentioned in your previous reply that water gmes change the speed automatically . So is there a possibility to see the speed
varation and the curve generated ?
You can use time based controls and set the speed you want based on time.
To view the resulting curves and operating points after a run, right click on the pump and pick Pump Curve.
This link has more information on using variable speed pumps in WterGEMS and WaterCAD.
Regards,
Scott