Electronic pumpcontrol system

A pumping system, comprising:

• a container for liquid,
• an inlet for the inflow of liquid entering the container,
• means for ascertaining the liquid level in said container and for generating a first signal corresponding to the current liquid level,
• a conduit for liquid being pumped out of the container,
• a plurality of pumps each having an inlet communicating with the interior of the container and an outlet communicating with said conduit,
• pressure sensing means in said conduit for sensing the backpressure against which pumps in operation are pumping and for generating a second signal corresponding to said sensed backpressure,
• a pump controller for receiving said first and second signals and for starting and stopping individual pumps,
• an addressable memory operatively connected to said pump controller, means for storing, in said addressable memory, values corresponding to pumping rates vs. backpressure for each of said pumps, along with high and low backpressure values for each pump, and
• processor means operatively connected to the pump controller, the processor means being programmed such that:
• (a) on high backpressure, the pump controller avoids pumpstarts which will not result in a net increase in the total pumping rate;
• (b) on a decrease in backpressure, the pump controller allows more pumps to start when called for, and allows for the starting of more pumps than the minimum necessary, in order to decrease the duration of pumping;
• (c) the pump controller avoids a pumpstart under conditions which, given the stored high and low backpressure values for the respective pump, would result in the pump undergoing rapid on/off cycling;
• (d) the pump controller avoids the starting and stopping of pumps on pressure surges, by delaying any action for a given time period which is longer than the duration of a typical pressure surge.

A pumping system, comprising:

• a container for liquid,
• an inlet for the inflow of liquid entering the container,
• means for ascertaining the liquid level in said container and for generating a signal corresponding to the current liquid level,
• a conduit for liquid being pumped out of the container,
• a plurality of pumps each having an inlet communicating with the interior of the container and an outlet communicating with said conduit,
• a pump controller for receiving said signal and for starting and stopping individual pumps so as to maintain the liquid level between predetermined upper and lower limits,
• an open channel flowmeter in said inlet, the flowmeter generating a further signal corresponding to the liquid volume inflow the said container,
• a processor means operatively connected to said pump controller,
• an addressable memory operatively connected to said pump controller,
• the processor means being programmed so as to assign, to different levels of said further signal, different empirically calculated average liquid volume inflow rates computed on the basis of:
• (a) a known container volume between a lower and an upper level within the container, and
• (b) the length of time required for the liquid surface in the container to rise from the lower to the upper level when no pumps are pumping,
• the processor means storing such assigned rates in said addressable memory, the processor means further including an extrapolation and interpolation capability whereby, during periods of high inflow when the liquid level remains high despite the running of all pumps, the processor means can estimate inflow on the basis of said third signal and the memorized assigned rates in the addressable memory.