Controlling Pumps Using a Solar-Powered Repeater System
A local water cooperative near Asheville, North Carolina supplies water to its customers from an elevated reservoir to use gravity to provide consistent water pressure. When the reservoir tank level gets too low, the co-op needs to pump water from a well in the valley to fill the reservoir. They wanted to use a float switch to indicate when the reservoir levels dropped too low, but needed a way to get the information back to the pump station almost a mile away.
The customer required a solution that would activate a pump once the reservoir got low with the pump located almost a mile away. Because of the distance and elevation change between the reservoir and pump station, it was difficult to get the signal back wirelessly; it would not be possible to do it in a single hop.
Additionally, the solution would need to supply power at the remote location of the reservoir tank as the tank did not have its own power source.
A Performance Mapping (PM2) Gateway and two PM2 Nodes (900 MHz, 1 W models), using the 1R mapping option, transmit the signal from the reservoir to the pump station. One of the Nodes was installed at the reservoir with the float switch as its input. A solar panel was used to power the float switch and the Node. The Gateway, also powered by a solar panel, was installed part way down the hill to act as a repeater and ensure the signal was strong between the reservoir and the pump station. The second Node was wired into the pump station’s PLC. When the signal from the float switch indicated the reservoir’s levels were low, the pump turned on.