Applies To Product(s): Bentley WaterGEMS, Bentley WaterCAD Version(s): 08.11.xx.xx Environment: N\A Area: Modeling Subarea: N\A Original Author: Scott Kampa, Bentley Technical Support Group Problem Is there a way to set up the pump controls so that a pair of pumps are controlled by the hydraulic grade of the tank, but only one pump will be on at a time? In other words, the pumps will cycle back and forth. When the tank reaches a minimum elevation, the first pump will turn on. However, the next time the tank reaches the minimum elevation, the second one will turn on instead. Solution There is a way of modeling cycling pumps using control. Please review the attached model. Please note that this model was created in build 08.11.02.31. You will need this build or later for the model to run. In order for the cycling to work, you will need a dummy pipe. This pipe will open and closed based on the controls and will help govern which pump is open to supply the tank. Assume that the tank is called T-1, the pumps are called PMP-1 and PMP-2, and the dummy pipes are called Control Pipe and Fake Pipe. Fake Pipe is only there to help clean up user notifications. Keep this pipe Open. See the image below for the general setup. If you want the Pump-1 to supply the tank first, Pump-2 will be off and Control Pipe will be closed. Then set up the controls to say: IF (T-1 HGL xxx) and (Control Pipe Status = Closed), THEN (PMP-1 status = On) To turn off Pump-1: IF (T-1 HGL xxx) and (PMP-1 Status = On), THEN (PMP-1 status = Off) and (Control Pipe Status = Open) Then for Pump-2 to supply the tank: IF (T-1 HGL xxx) and (Control Pipe Status = Open), THEN (PMP-2 status = On) To turn off Pump-2: IF (T-1 HGL xxx) and (PMP-2 status = On), THEN (PMP-2 status = Off) and (control Pipe Status = Closed) This work flow could be used with the SewerCAD solver as well. Model Files Cycling between Pumps - WaterGEMS model
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