Performance Curve Of a Pump.

Hi All

i am working with PCS 7, and asked to plot a graph representing the performance curve of pumps. I need to plot below 4 curves;

1: Total Developed head (THD)
2: Net positive Suction Head (NPSH)
3: Efficiency
4: Power input

Can anyone guide me how to implement this with PCS 7. What tools and features I must used and which parameters do I need to plot the performance curves.

Thanks in advance
Raheel

If you are using the PCS 7 APL, I would add a APL block like MonAnL or MonAnS for each analog value. Check that the output value is configured to go into the tag logging.

Then you can use the trend group button in the bottom navigation, and add a trend which contain the 4 values, or you create your own trend object with these 4 values inside a pdl.

If you have a pump using an APL motor block like MotL, you can link two of the four values to UserAna1 and UserAna2 of the motor block. Then these 2 values are shown inside the motor popup window. And you can configure the trend curve inside the pump-popup to show these two UserAna values. But as far as I know it's not possible to show all 4 values in that trend.

Don' know anything about PCS 7, but I know a little about pumps.

To develop these parameters you need:

- Barometric pressure (for NPSH, which is measured in absolute pressure). This may be measured or assumed from site elevation, depending on accuracy needed.

- Pressure at the pump suction flange. This will be below atmospheric.

- Pressure a the pump discharge flange

- Flow rate through the pump

- Specific gravity of the fluid. If water, it is approximately 1.0. However, depending on what you use the measurements for and the required accuracy, you may need to measure and correct for temperature.

- You don't identify which efficiency you want. If it is pump alone you will need to measure the torque and speed at the pump shaft or else know the motor efficiency accurately at actual power output (not just full load or nominal), and measure true power at the motor (not just amps and volts). If the motor is powered through a VFD you can probably rely on the drive's power output reading. If you want system efficiency then you need to measure power at the starter or VFD line side.

- Power input: see above

The hydraulic institute has some guidelines. www.pumps.org

A lot depends on what you need the curves for. If it is a performance guarantee wit a penalty the requirements are a lot more demanding than if you just want to use it for occasional reference for monitoring maintenance needs.

For PCS 7 there is also a special diagnostic function block for pumps available:

http://w3.siemens.com/mcms/process-...agnostics-of-mechanical-plant-components.aspx

Hi Thomas/ Tom

Thanks for your valuable information. I've also read much about performance curve.
I've got the formula's to calculate those parameters. Also I've all the required information which I need for calculation.
However can anybody tell me how shall I proceed from the software part to achieve the four different realtime curves.

Attached are the 4 curves which i need to plot with real time values.

Have you checked the link to the PCS7 library I've posted above? I think that's exactly what you need.

If you want to realize this by your own, then you cannot use the standard functions I've mentioned in my first post. You'll need another control to display static X-Y curves, like the WinCC function trend control.
If you want to get the standard PCS7 design and functionality (reusable faceplates, alarming, trending, etc.), this is a lot of work.

I'm curious as to your objective. Are you trying to create a "curve" by running the pump at different flows or are you trying to calculate actual performance and compare it to the manufacturer's curves?

I also wonder the purpose of the curve. Unless you are tracking the degrading efficiency of the pumps in service it seems a little of busy work.
If you want efficiency and have the flow and pressure just track pump power.
If you can change speed I assume a VFD and the ability to read power output and perhaps RPM.
Really power vs weight of water moved tells all in my opinion.