Radio, phone and data links

Ergon Energy of Queensland, one of Australia’s largest electricity companies, has partnered with Zetron to develop and implement a new, integrated, customised communications system for the utility.

The two companies created a solution that takes into account the needs and goals of a variety of system users as well as management.

The result is an integrated communications system that has improved the centralisation, management and execution of communications throughout Ergon’s vast operational area.

Ergon undertook a significant program to revamp the control systems that manage the electricity distribution network throughout regional Queensland. The program included changes to the field communications network that controls and coordinates work on the electricity network.

As part of this effort, it centralised its control functions into two main control centres — one in Townsville and the other in Rockhampton. Upgrading included enabling the existing field communications network to allow voice communications between each centre and deployed field crews.

Zetron and Ergon worked closely to design, configure and install the new communications system. The upgrade involved installing a six-site Acom Advanced Communications System within the control centres: one main centre each in Rockhampton and Townsville, and four regional centres in locations throughout Queensland.

The new system included:

• Network operator controls;
• Voice switching equipment;
• Line interfaces for both radio and telephone services;
• Wide-area interfaces to support communications between sites.

In addition to devising and deploying the new system, Zetron also provided system documentation, factory-acceptance testing and training for Ergon operations and technical support staff.

At the heart of Ergon’s system is the Acom DS3 switch (ADS) that uses a 44.736 Mbps redundant backbone. In the current generation of Acom this provides capacity for up to 2200 line interfaces and 128 console interfaces.

Each Ergon site consists of multiple ADS units forming a redundant switching backbone with dynamic, low-bandwidth intersite bearer interfaces (ISBs) to connect to at least two other sites.

These bearer interfaces have now been in operation for a couple of years and allow operators at one site to access line interfaces or operators that terminate at any of the other sites.

The bearers are configured to be used in a combination of ‘always-on’ and ‘on-demand-only’ services.

This forms a mesh network that allows Ergon to support a wide-area intersite communications system. It also provides multiple communications paths without incurring large intersite bearer costs.

Radio and telephone resources are connected to the Acom ADS at Rockhampton and Townsville via G.703 digital connections to redundant 1+1 hot-standby line sub-racks (ALS) at each centre.

Line interface modules in the ALS at each site are installed in matched pairs through a changeover unit. This provides fully redundant, hot-standby lines that interface with each of the field voice circuits for both radio and telephone.

Line interfaces are a combination of local-only and system-wide lines. These include radio circuits which are four-wire, E&M interfaces with full selective calling (SELCAL) encoding and decoding functionality performed by signal management unit (SMU) digital signal processors in the ALS.

Radio caller ID status is displayed on the operator’s console screen in a call history window. Operators can selectively call individuals or groups of mobiles from a soft keypad on the console or directly from the radio call history list.

Acom can also route incoming radio calls to specific operator positions based on caller ID. This allows operators to take care of radios in specific geographic regions.

Analog telephony cards provide connections to local PSTN and OTN telephony circuits. The PABX circuits transmit over ISDN E1 links on which full automatic call distribution functionality has been enabled. This includes recorded voice announcement functionality and interactive voice response.

Mobile radios can also make telephone calls without assistance from the operator. A unique selective call sequence is sent to the Acom from the mobile. The Acom then decodes this and automatically connects a phone line to the radio channel. The mobile can then dial telephone numbers via its DTMF keypad microphone.

Windows-based consoles with touch-screen monitors provide the software application that allows operators to control which audio sources are switched to the operator’s console position.

The console units are on redundant E1 G.703 loops connected between two backbone switches. Redundant loops ensure that there is no single point of failure for the console connections.

The current voice communications network provides coverage throughout the power distribution network. In areas where radio coverage is poor, communications are supplemented with satellite telephones.

Mobile telephones throughout the business are used for non-operational communications and also provide a backup to the radio network.

Each control centre is designed to be able to control the entire electricity network if any of the other control centres becomes unusable for any reason.

The new system is improving the coordination and efficiency of communications throughout Ergon.

In addition, the system supports the various needs of those who use it, including network operators, fault-analysis officers, schedulers, dispatchers and other staff associated with controlling field operations.

Zetron