CASE STUDY: EA Network's DMR Tier III

New Zealand utility EA Networks has installed a Tait Communications DMR Tier III solution to connect and protect its widespread South Island electricity and fibre network.

EA Networks began life as the Ashburton Electric Power Board in 1923, but changed its name to Electricity Ashburton in the 1980s when it became a co-operative company – that is, owned by the customers who are connected to its network. By the beginning of the present decade it was decided that the brand name, although having high value in the district, had become a bit limiting. So in 2012 the company changed its trading name to EA Networks.

Its electricity grid coverage area is quite vast, spanning the Canterbury Plains in the South Island - from the Rangitata River in the mid-south to the Rakaia River in the north, and from the east coast to the middle of the Southern Alps. The main towns in the region are Ashburton (population about 16,000), and Methven, which is the support and accommodation centre for the Mount Hutt ski fields.

About five years ago, EA Networks also began deploying a fibre optic public broadband network. Today, its electricity distribution and fibre networks reach approximately 17,450 consumers through almost 3,000 kilometres of distribution lines.

EA Network's coverage extends across the Canterbury plains to the Southern Alps. Credit: Bernard Oh/Flickr CC.

An evolution in radio

With such a long history, it is no wonder the company has seen several different radio communications technologies come and go.

“We started with an old Tait A-band AM analogue system, which in turn was replaced with an FM analogue system about 18 years ago. The system only had one repeater on a hill and suffered from coverage issues, particularly on the north-east corner of the network,” says Brendon Quinn, the company's Network Manager. “Just prior to putting in the DMR network we deployed an analogue voting system using three repeaters, but it was never that successful.”

Because of the issues they were having with coverage, the analogue voting system and ageing equipment, the company decided to replace the whole network. “DMR wasn’t available from Tait at that time, so we looked at both Motorola’s and Tait’s P25 systems,” says Quinn. "We had started installing the P25 system when Tait DMR became available, so we decided to change to DMR. We were actually a beta trial site for Tait, so it was a learning and testing process for both organisations.”

The five-site DMR Tier III trunked solution commissioned by Tait comprises TB9300 base stations, TM9300 mobile radios and TP9300 portable radios.

EA Network's Brendan Quinn in front of the Ashburton repeater station.

But the company wanted to go beyond simple voice comms and include other features that are considered de rigueur these days. “We wanted to be able to do our own GPS tracking - which had previously been done via a cell phone connection - and we wanted to introduce other digital features in the future such as short data messaging," says Quinn. "We also wanted the ability to have multiple channels in use concurrently, so we are trialling Tait GridLink, which is a SCADA system using the DMR infrastructure.”

The first installations, including base stations and a limited numbers of radios for the trial, were in place about 12 months ago. Permanent base stations and a full complement of mobile radios were up and running by September and October 2013, with the full set-up functioning properly just before Christmas. Final acceptance testing came in March 2014.

The equipment

At the five sites, existing base station equipment was replaced with Tait dual-channel TB9300 base station units, and other works included replacing or changing duplexers, reciters, antennas, T-passes, and re-tuning some channels.

“We already had fibre optics to each repeater site and the inter-repeater links use their own Layer 3 private network,” says Quinn. “The switches at each site are Allied Telesis X600s, which connect back to our core Extreme Black Diamond switches and then to our control room, Tait nodes and so on. All inter-site comms are duplicated with a less-than 50 millisecond fail over time.”

Sixty-six TM9300 mobile radios were supplied, being 31 vehicle-mounted and 35 handheld.

“From a voice perspective it is complete,” says Quinn. "GPS, call management and despatching via PC terminal is currently being deployed, and SCADA is going into a trial phase."

A Clevest location services application is enabling Automatic Vehicle Location and geo-fencing of the company's mobile workforce. The ability to see where its fleet and workers are means EA Networks can respond more quickly to incidents and maintain service to its customers.

Credit: Bernard Oh/Flickr CC.

Putting it to the test

“The digital mobile network was invaluable during the region’s severe windstorms in September 2013,” says Quinn. “The clarity of voice message over the digital network made it easier for our field workers and dispatch centre, to communicate effectively without the need to repeat instructions.”

The storms highlighted other potential vulnerabilities that the radio network has historically faced, namely congestion at critical times and visibility of the workforce. EA Networks worked with Tait to identify capabilities of the new DMR network that will help it solve these issues in the future.

“The recent storm events really brought home how important it is keep ‘visibility’ of our on-ground workforce all the time,” says Quinn. “The DMR network gives us that, plus it helps us to improve our overall efficiency to that we can provide better service to our customers.”

Ongoing network maintenance, monitoring and support services are being provided by Tait as part of the overall solution.

And Tait is finding increasing interest in the system.

“Following the successful DMR Tier III implementation, we've been successful in securing a major North American utilities contract that involves installing the Tier III solution across more than 20 sites,” says Brett Smythe, General Manager, Tait Communications Asia Pacific. “We expect to see more utilities around the world adopting the platform over the coming years as its full potential to transform utility workforce management is realised.”