Test & measurement
Going IoT loco down in Kololo T
he Kololo Game Reserve is located near Vaalwater, Limpopo. Because of its location in a rural area, the reserve
requires its own water source. Kololo’s water system consists of three
stages: a water well, eight accumulating tanks, and a distribution system of pipes and hoses. The water from the 100m well is pumped over 1km into the eight 5,000l tanks located on a hill. From here, the water is distributed downhill, via gravity, to the lodges.
Measuring levels
Measuring the water levels in both the well and the tanks is important to determine water availability. To assist in this regard, KELLER installed a complete level measurement system in one of the tanks in February 2020. As all eight tanks are connected, the level measured is representative of the level in all the tanks. Due to Kololo’s size, a wireless Internet of
Things (IoT) solution was needed. However, the reserve’s rural loca tion meant minimal cellular coverage. The chosen solution therefore communicates wirelessly via a LoRa (long range) network. A typical local LoRa network consists of three
basic elements: 1. A digital sensor or gauge 2. A LoRa transmitter
3. A LoRa gateway – the receiver, which is connected to the internet by Ethernet or Wi-Fi.
48 August 2020 Instrumentation Monthly In the case of Kololo, the LoRa gateway is a
Laird Sentrius gateway, and the LoRa transmitters are KELLER’s own ADT1 LoRa modem. A KELLER Series 36XW digital level sensor is connected to the modem, measuring pressure and temperature. The ADT1 retrieves the data from the level sensor and transmits it, together with barometric pressure and air temperature, to the LoRa gateway. Finally, the LoRa gate way forwards all the data via the internet to KELLER’s Kolibri Cloud where it is stored. Data can be viewed in the Kolibri Cloud web
app, with additional features including exporting and printing of data, converting data to other units or even tank content calculations, among others.
installation
Installation and set-up took some time, as it required finding precisely the right transmitting power, without overpowering. Given the location, it would be difficult to return to change batteries, for example. After installation and set-up, the system
started measuring every hour. A day later, the data showed a downward
sloping chart. Inspection of the difference between two measurements during the night showed a difference of approximately 100l/hour. A leak was the only possible cause. An inspection found that one of the pipe threads was partly pulled out of junction in
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