TEST & MEASUREMENT
Taking tests to the transformers Nick Parton, Middle East and Africa Regional Sales Manager, Megger describes how his company worked with their local Saudi distributor to develop a unique transformer test van
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egular testing of power transformers is one of the most effective ways of enhancing the reliability of electricity supply networks. Because of the size of power transformers and the difficulties associated with taking them out of service for anything but the briefest of periods, the tests almost invariably have to be performed with the transformer already installed. This raises the problem of how best to take the test equipment to the transformer. A typical solution is to load the instruments needed into a van and then set them up on site. This approach works well enough, but the time needed to set up the instruments before starting the tests and then break them down after testing is complete means that it is a relatively inefficient way of operating, especially when large numbers of transformers need to be tested on many different sites. With these issues in mind, Saudi Electric Company (SEC) in Riyadh approached Megger distributor
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Al-Abdulkarim Holding for help in devising a better solution. In response, the company, working in conjunction with Vitaldrive of Cyprus, developed a unique and comprehensively equipped transformer test van. This has been designed so that, as far as possible, the instruments it contains can be used without the need to remove them from the vehicle, which greatly reduces the time needed to test a transformer. A key feature of this arrangement is a set of cable drums at the rear of the vehicle with special 30-m test leads. These enable connections to be made to the transformer quickly and conveniently even in situations where the vehicle cannot be parked adjacent to it. The test equipment fitted to the vehicle includes a turns-ratio test set, a transformer ohmmeter for winding resistance tests, a tan delta and capacitance test set, a frequency response analyser for rapid overall condition assessment, and a highvoltage insulation tester. All of the instruments are conveniently mounted
in a central control compartment within the vehicle, which provides a comfortable working environment for the operators. Numerous engineering challenges were encountered during construction of the transformer test van, not the least of which was ensuring that all of the instrumentation would work correctly and reliably with the unusually long test leads. It was also necessary to provide special connectors and switching arrangements to ensure that the vehicle could be configured quickly and conveniently to provide any combination of tests that might be needed to suit a particular transformer. Megger’s development and application support engineers from sites around the world contributed to a solution that would effectively address these problems. The result is a versatile, convenient and reliable test vehicle which has impressed the SEC with its high standards of finish and functionality, and which is providing big savings for transformer testing. FEBRUARY 2013