Savannahs, powerful rivers, migrating herds of animals – power transformers. The southern regions of Africa owe their mass distribution of power to efforts made in the late 1960s and early 1970s. Correspondingly, transformers at hydroelectric power stations and extremely long overhead power lines also originated during this time and have therefore now been in use for 40 to 50 years.
As Kobus de Villiers, Managing Director at Reinhausen South Africa, says, “We believe that the number of power transformers across Africas southern regions that will need overhauling will increase enormously.” The operators are therefore faced with a huge logistical problem: Countries like Namibia, South Africa, and Botswana have decent infrastructures, but very few installations where the work can be undertaken. The transport routes are therefore long. “And in Zimbabwe, Zambia, and Mozambique, transporting transformers is a logistical nightmare. Many primary substations are almost inaccessible.”
There are also very few roads that are in an acceptable condition. The river routes through which the transformers were once shipped are largely obstructed by dams today. And if there are bridges, they are often not designed to withstand those kinds of loads. “This means we have to take ridiculous detours. So, I asked myself: Wouldit not make much more sense to perform the high voltage tests on site?” says de Villiers.
“The mobile high voltage tests allow us to create a more reliable network.”Nico de Jager, City Power Johannesburg
Günter Panzer from Reinhausen Germany introduced de Villiers to Ralf Bergmann, CEO of HIGHVOLT – a long-established company that is part of the Reinhausen group and specializes in high voltage measurement and testing. The three men met to discuss possible mobile test solutions. With this meeting in mind, de Villiers then picked up the phone and placed a call to Dresden.
Kobus de Villiers brought the testing truck to Africa. He certainly cannot complain about a lack of orders coming in. (© Craig Mannheim)
After maintenance, an error message or commissioning of a power transformer, the truck-based team moves in and makes sure that everything is working 100 per cent as it should. (© Craig Mannheim)
Setting up for the test in Johannesburg: The power transformer is only dismantled if the test identifies a fault, thus significantly reducing costs for operators. (© Craig Mannheim)
DRIVING REPLACES DISMANTLING
On the receiving end of de Villiers’ phone call was Mario Jochim at HIGHVOLT. For a number of years now, HIGHVOLT has been constructing trucks with integrated testing technology and static frequency converters – equipment which can be used to conduct induced voltage tests or no-load loss measurements in the field, to name a couple of examples. Normally, obligatory tests of this kind require dismantling the entire power transformer, removing the oil and transporting the transformer to a facility for testing, before bringing it back, replacing the oil, and reconnecting the equipment.
“If a transformer can’t come to the test facility, the test facility goes to the transformer.”Kobus de Villiers, MR South Africa
As Jochim explains: “This involves a lot of time and huge financial outlay, both of which can usually be avoided by using a mobile testing station.” Testing trucks are the perfect solution for southern Africa – and to date there has been nothing in the wider area to provide this service. On de Villiers’ order, two mobile stations were brought in – one for alternating current, the other for direct current – and Reinhausen set to work.
MOBILITY WITH DEPENDABILITY
After a few initial deployments in the Johannesburg area, the trucks will soon make their way to other countries in the region with ten Reinhausen experts on board. As de Villiers puts it: “They will mainly be used for standard high voltage tests at power transformers, which need to be carried out when a fault has been reported, after maintenance has taken place, or before commissioning.” Now, transformers will only be dismantled and shipped off to a transformer facility if they actually show signs of a defect – not as standard practice.
THESE TESTS ARE POSSIBLE WITH THE MOBILE TESTING STATION
1. Induced voltage test
- Winding insulation test (in single-phase and three-phase transformers)
- Insulation test
- Partial-discharge test
2. No-load loss measurement
3. Load loss measurement
4. Applied voltage test
“In this way, we can help our customers realize huge cost savings.” City Power, the utility provider for Johannesburg that had Africa’s first mobile high voltage test performed, is one example of where these savings could arise. Nico De Jager, a city councilor responsible for infrastructure, is excited about the concept: “These mobile high voltage tests are an extremely cost-effective solution for us. As we can carry out appropriate diagnostics analyses based on the data they provide, they also allow us to make more informed decisions about the maintenance and repair work necessary for our high voltage transformers. This means we can deliver a more reliable supply of power.”
Even the very first deployment of one of the testing trucks in Johannesburg attested to this. A fault was reported in the network, but it was unclear whether a power transformer was the cause of it. The Reinhausen truck swung into action and, after just a few days, discovered that the transformer was completely intact – so the fault was located elsewhere. As de Villiers says: “Normally, the transformer would have had to be dismantled and tested at a facility – meaning months’ worth of downtime. City Power would have had to spend in the region of 13 million rand just to find out that everything was okay. Our mobile measurement solution cost a fraction of that.”
YOUR PERSONAL CONTACT
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