Ausgrid is the biggest electricity distribution company on the eastern coast of Australia, and in the state of New South Wales it supplies electricity not only to the Central Coast and Hunter Valley regions, but also to the millions of people in Sydney. Consequently, the grid territory is shaped both by rural areas and by densely populated urban centers. Yilin Xu and his team of 21 people are responsible for testing the grid structure at Ausgrid. This includes both cables and overhead power lines as well as operating equipment in the substations. This type of testing is set to become ever more important in the future. One reason for this is that many transformers are already 40 to 60 years old, but on top of this demands on the power grid are increasing due to the integration of solar power and electric vehicles.

“Our challenge will be to offer the corresponding services to ensure continued reliability of the grid,” explains Xu. But the vehicle previously being used by Ausgrid for testing was already around 50 years old, so it was far from state-of-the-art. This meant that the electricity distribution company needed a new mobile testing system to ensure that it was adequately equipped for the challenges of the future. One important prerequisite was that the new truck could not exceed a length of 11.2 meters and needed to have a small turning circle. Xu explains: “Many of our substations are very narrow and can only be reached via narrow access roads.” Unfortunately though, there is no off-the-shelf solution available that meets these requirements. All these considerations meant that there was only one place for the testing expert to turn to: HIGHVOLT.

HIGHVOLT has many years of experience of developing and building AC testing systems. With this method, the dielectric condition of the operating equipment is examined. To do this, operation is ramped up to an increased test frequency and an increased test voltage in order to test whether partial discharges occur in the object under investigation. If these discharges exceed a certain threshold, this indicates weaknesses in the insulation system. HIGHVOLT has also earned itself a great reputation in the field of mobile solutions for testing systems. For example, the experts in high voltage have already mounted a cable testing system on a semi-trailer truck. However, in practice the resulting vehicle would be much too long for this application. A container solution of the type that has already been built a number of times was out of the question for the same reasons.

For Andreas Thiede, who was responsible for the project as Head of Innovations at HIGHVOLT, this meant that this request was both a huge challenge and a real first at the same time: “The only option was to install the testing system on a compact truck. We had never done anything like this before.” Key parts of the equipment included a transformer, measuring and compressed gas insulated capacitors, as well as a cabin with the frequency converter for test monitoring.

As well as this, the team headed by Andreas Thiede addressed many other specific characteristics of the required solution. For example, Australia has fairly strict requirements in relation to occupational health & safety. The folding steps for entering the truck therefore needed a railing on both sides. Another important aspect is the very high levels of UV radiation in Australia, on top of which the air in Ausgrid’s grid territory has a higher salt concentration because of its closeness to the sea. This plays an important role for example when considering which materials to use for the truck tarpaulin. “Finding a way to house all the technology in such a tight space, and with the weight distributed as optimally as possible, was anything but easy. But we managed it!” reports Thiede.

HIGHVOLT has now delivered the first mobile testing truck to Ausgrid, and Xu could not be happier with the results: “With our old testing system we could only carry out tests at 50 Hz, but now we are far more flexible in terms of test frequencies – even 100 or 200 Hz are possible. This makes our measurement results much more accurate.” One thing that makes work a lot easier for him and his team is the state-of-the-art equipment in the climate-controlled cabin. Test technicians have a user-friendly touchscreen with which to operate the system, and the test sequences can be programmed in advance. The mobile testing system can also be set up for use very quickly – all that the employees from Ausgrid need to do is slide back the tarpaulin, plug in the cables for the power supply, and connect the test object. The test itself is completed in around an hour. Another aspect that Xu really appreciates is the technical support on offer: “We can turn to HIGHVOLT for assistance at any time, and help can even be provided remotely!”