Construction World June 2023

DAMS AND RESERVOIRS

RADIO TELEMETRY NETWORK ENABLES BETTER SERVICE DELIVERY FOR DAMS

R emote monitoring specialist Omniflex has completed a system revamp of legacy radio monitoring equipment for Lepelle Northern Water, a state-owned enterprise (SOE) responsible for providing potable water to South Africa’s Limpopo province. In 2018, Omniflex was engaged to replace an obsolete radio telemetry system used to monitor reservoirs and control remote pumps across the region with the latest generation License Free Teleterm Remote Terminal Units (RTUs). The legacy system prior to Omniflex’s involvement used analogue radio over license-band frequencies, on now-obsolete equipment. The Durban-based automation and control engineering company supplied and installed a digital, license-free radio network capable of communicating bidirectionally between multiple outstations across the region. These compact, fully radio-integrated units have universal inputs and outputs servicing analogue and digital signals from twelve up to hundreds of I/O. Flexible communications ports allow direct connection to field devices such as water meters or variable speed drives using Modbus. A working power range from 9 to 30 Vdc makes them the ideal product for battery-backed applications, enabling status reporting of mains power to the site and reservoir levels even during power outages. “We took advantage of a high site, a secure

area that sits atop an old mine dump, as the main repeater station,” explained Ian Loudon, international Sales Manager at Omniflex. “It was the line of sight from this structure that enabled us to transmit at 868 Mhz, a license-free frequency in South Africa: enabling us reach all the intended targets and provide unrestricted options to add any new sites as and when required using the Teleterm range of products.” The region’s water is sourced from the Olifants river, next to which sits the region’s water treatment plant. At this site, Omniflex installed a large human-machine interface (HMI) and integrated the radio network to a supervisory control and data acquisition (SCADA) system. This allows management of all the water pumps, reservoirs and bulk water usage meters in the system, as well as historical record keeping. “We also offered to incorporate an SMS solution to monitor the river level further upstream the Olifants,” said Loudon. Radio monitoring systems of this sort have applications across the utilities industries that have service delivery commitments to consumers. Just as equipment failure in drinking water supply chains must be planned for and mitigated, power supply networks must also be monitored to allow swift action should a sub-station trip, and residential and industrial areas lose electricity. 

36 CONSTRUCTION WORLD JUNE 2023