Radio telemetry network facilitates service delivery for water provider

Omniflex has completed a system revamp of legacy radio monitoring equipment for Lepelle Northern Water, a state-owned enterprise 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 License Free Teleterm Remote Terminal Units (RTUs).

The legacy system prior to Omniflex’s involvement used analog radio over licence-band frequencies, on now-obsolete equipment. The Sydney-based automation and control engineering company supplied and installed a digital, licence-free radio network capable of communicating bidirectionally between multiple outstations across the region. These fully radio-integrated units have universal inputs and outputs servicing analog and digital signals from 12 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 9–30 VDC makes them suitable for battery-packed applications, enabling status reporting or mains power to the site and reservoir levels during power outages.

Ian Loudon, International Sales Manager at Omniflex, said the company used a high site, a secure area that sits atop an old mine dump, as the main repeater station. “It was the line of sight from this structure that enabled us to transmit at 868 MHz, a licence-free frequency in South Africa: enabling us to reach all the intended targets and provide unrestricted options to add any new sites as and when required using the Teleterm range of products,” Loudon said.

The region’s water is supplied by the Olifants River, next to which sits the 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 enabled the management of all the water pumps, reservoirs and bulk water usage meters in the system, as well as historical record-keeping. Omniflex also offered to incorporate an SMS solution to monitor the river level further upstream the Olifants.

“56 km over hilly terrain is much too far for unlicensed radio communication, indeed even licence bands would need a repeater, so a daily SMS report can monitor the water height. This device also notifies the pump plant if the water level falls or rises outside a desirable range,” Loudon said.

Radio monitoring systems of this sort have applications across the utilities industries which 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 be monitored to allow swift action in case of emergencies.

Image credit: Omniflex