Minimum Relative Speed Setting

Question

Hi, I have a pretty simple question. Is there a setting to control the minimum relative speed factor for a variable speed pump? Currently the pump drops down to about 0.36 relative speed factor with a flow of 0 gpm. This is not realistic and would like the pump to stop decreasing speed when it reaches .67 relative speed ( i.e. 40hz/60hz = 0.67). 
 Thanks in advance.

Tom Walski · Accepted Answer

You should run the model at a speed of bout 0.67 and determine what the flow is at that speed. Then if the flow drops below that you'd have a control that say IF (Q<x, THEN PMP is off). Of course, you'll to come up with some other rule to turn the pump back on. 
 
You may want to look at Scenario energy cost and calculate $/MG and wire-to-water efficiency at a range of speeds, to determine the speed where the cost to run it is not worth while.