Efficient Pump Control Simplified: Utilizing VFDs and PID Controllers for Isolated Water Supply Systems!
Triol Corporation
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Simplifying and improving capabilities of a local water supply system with an extended PID controller combined with pump load profile control
In designing some isolated water supply systems for separate residential buildings or gardening areas the main goal is to make the pump control as simple as it possible but without efficiency and safety loss.
It is always possible to integrate fancy intellectual operation modes using a PLC and flow sensors, but for some cases, it would be really redundant. Let’s consider how to resolve the challenges of such systems using only the VFD with a PID controller and a simple pressure gauge.
Having a pump that delivers water from the reservoir directly to the cranes of small amounts of consumers it is quite easy to use a classic configuration where the VFD is connected to the pressure gauge by 4-20 mA feedback and controlling the speed of the pump to maintain the exact pressure in a pipe.
But what happens if all consumers close their cranes? The VFD will lower the setting and run at a minimal speed all the time while there’s no consumption for a long time. This mode is very aggressive for a pump and spends the energy for nothing.
In this case, the PID sleep mode integrated into the controller solves the problem. When all valves on the consumer's end are closed the VFD can detect high power consumption at a low speed and completely stop the pump until some consumer opens his valve and pressure drops. Detecting the pressure decreasing VFD wakes up and starts the motor again satisfying the flow demand.
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As you can see, the VFD controller can manage a simple water supply system completely alone containing the PID sleep mode. Also, specific pump protections such as dry run or leak detection protection based on a combination of load profile and pressure control can be very helpful and building a modern and professional pump control system.
This is what we offer in our VFD Triol AT24-UB with a pump control program.