I am new to trying to model VFD Pumps. I have a single pump running on a single type 3 curve without controls besides on-off levels. Looking at the pump operation curve, the purple diamond indicates that the pump is operating on the curve most of the time but at various time steps the red line of the curve changes so that the purple indicator is no longer riding along it. It looks like the pump is operating at the same flowrate but the curve changes. Is this a graphical error or is there something going on? I've attached screenshots fr reference.
Also, what is the best way to ensure that the pump and forcemain are operating correctly according to the system curve?
Thanks for any insight.