How Does a TYPE3 Variable Speed Pump Work in SWMM 5?

Subject:   How Does a TYPE3 Variable Speed Pump Work in SWMM 5?

In a SWMM 5 Type3 pump the flow is a function of the head difference between the downstream node head and the upstream node head (Figure 2) but the pump rules can be overwritten by a RTC Rule as in the attached example.   The RTC Controls in the example change the pump setting as a function of the depth in the Wet Well.  There is one pump between the Wet Well and Force Main but the Pump Setting varies from the RTC rules based on the depth in the Wet Well (Figure 1). As you can see in the composite Figure 2, the setting varies from 0, 1, 2 and 3 during the course of the simulation.

Figure 1.  How a Pump Flow is Calculated in SWMM 5.

Figure 2   RTC Rules and Schematic of a TYPE3 Pump in SWMM 5 with Force Mains Added along with three depth settings for a Variable Speed Pump or VSP.