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Help With setting up a VSP or VFD with 4 pumps.

Hi, Working with SewerGEMs, GVF-Convex solver. I need your assistance in setting up a VSP or VFD with the below on and off (elevations) controls. I want to use the fixed head VSP type and use my control node as the Wetwell. probably with a target HGL at midway of the lead pump. I have read around quite a bit about the VSP battery and does not seem to get me to where I need to be. Can the experts help me on this?? All my pump curves for the 4 pumps are set up already. Anybody??

LEAD LAG 1 LAG 2 LAG 3
OFF -8.35 -8.35 -6.85 -6.85
ON -6.35 -4.35 -2.35 -0.35
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  • The concept of a fixed head is fundamentally inconsistent with the idea of pumps coming on at different levels. Either you have a fixed head or you have pumps that come on at different heads.

    For this complicated of a case, you could either set a level that you will maintain and use the VSPB or you could set up individual pumps each with several control statements along the lines of

    IF(Level > x and Level < y) THEN Pump setting = 0.z

  • Good. So, if I decide to use option one which is the using the VSPB, what will be the optimum control level I need to use to accomodate all 4 pump settings? As you can see 4 pumps OFF and ON settings spanning from -8.35 and -0.35. It appears I would not be able to associate additional levels with the VSPB. Correct??

  • Thanks very much Scott. I have rectified the issues you raised and the model is running.

    I guess my question you is how to control pump off. Tom/Jesse/Scott - Can you elaborate specifically (with examples if any) how to can shut multiple pumps off at the same time  to mimic power failure at a LS and any ideas how to estimate the timing from failure to first overflow.  I am not sure I have much control over WHEN the LS shuts off with Implicit solvers. Anyone??

  • There are a couple of ways to approach this.

    With the implicit solver, the easiest is to set the wet wells at some level and start the run with all the pumps off. To study how the system will recover after power goes off, set some high wet well level where pumps come on.

    With the explicit solver, you can use time based controls. See the Help topics Control Sets Dialog Box and Control Set Formats for the syntax of these control statements.

    Answer Verified By: Sushma Choure 

  • Thanks Tom. I think you missed my second question: "and any ideas how to estimate the timing from failure to first overflow". I am currently using the impicit solver. Also, how do I know which manholes overflowed first.??

  • There are a variety of ways to do this as well.

    You can look at the manhole property "Time to maximum overflow" which shows you when overflows are at their worst.

    You can color code by the property "Flow (overflow)" and move the Time Browser until something turn red (or purple or whatever color and size you'd like).

    You can view profiles along suspect paths and watch for when the HGL reaches the rim using the Time Browser.

    You can color code, annotate or view the property "Is overflowing" or "Is even overflowing?".

    You can do a graph of HGL and rim elevation vs. time for suspect manholes.

    We give you so many ways of checking this, there is no one single "right" way.

    Answer Verified By: Sushma Choure 

  • Thanks a bunch Tom. Do you know why  "Is Flooded" and "Ever Flooded" columns in the manhole Flex Table is not checked(display True)  eventhough calculated max HGL for my manholes are way above the rim elevation (in some cases about 3 ft or more. No Flow (overflow) calculated either.

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  • Thanks a bunch Tom. Do you know why  "Is Flooded" and "Ever Flooded" columns in the manhole Flex Table is not checked(display True)  eventhough calculated max HGL for my manholes are way above the rim elevation (in some cases about 3 ft or more. No Flow (overflow) calculated either.

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