PowerByte recently completed the installation and configuration of two Avtron SIGMA II Modbus gateways at Transgrid’s Broken Hill Substation. The work connected two existing Froment (ASCO) load banks to a clearly defined Modbus TCP communications interface for external monitoring and control.
The project
The site’s two load banks used their existing Froment SIGMA controllers for local operation. The requirement was to make their available operating data and supported control registers accessible to Transgrid’s external systems without replacing the load bank controls or changing the site’s control philosophy.
Each load bank was fitted with a SIGMA Gateway. The gateway communicates with the existing controller over the internal RS-485 network and presents a Modbus TCP server over Ethernet, using port 502. The interface exposes register data including status and alarms, electrical measurements, requested and applied load, available capacity, and supported load-control points.
Engineering and preparation before site
A useful part of this project was the preparation completed before mobilisation. Avtron’s technical documentation and SIGMA Simulator software allowed the team to validate the proposed integration and develop and test the communications configuration ahead of the site works.
Avtron’s technical team supported the preparation phase with equipment scoping, documentation and answers to technical questions. Their willingness to help across the Australia–UK time difference was valuable in getting the work ready before arrival on site.
Installation and commissioning
On site, PowerByte installed one gateway for each load bank, connected each device to the existing SIGMA communications network and configured the Modbus interface. Commissioning checks covered communications integrity, register mapping and scaling, and read/write operation of the exposed points.
Because the configuration and integration had been prepared in advance, the site work proceeded with minimal issues. The client was able to see the gateways connected and the pre-tested configuration brought onto the network, with less development and troubleshooting left to complete in the field.
A clear interface for the wider control system
The delivered scope was the communications interface and its documentation. It makes the load bank telemetry and supported commands available for an external client system to use. Transgrid retained responsibility for the SEL RTAC configuration, SCADA integration and any site-level automation or load-management logic.
The result
The project provides a documented Modbus TCP interface to both load banks and a practical foundation for Transgrid’s external systems to monitor their condition and issue supported commands. For PowerByte, it was another example of how careful pre-engineering, simulation and collaborative technical support can help simplify commissioning at a remote infrastructure site.
Project scope note: PowerByte’s work covered the SIGMA Gateway installation, configuration and documented communications interface. Site-wide automation, load sequencing and SCADA logic were outside this scope.
