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Published by Megger
November 2009 |
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| The industry's recognised information tool |
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ELECTRICAL
TESTER |
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In this issue |
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Beyond the Limits! |
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A superior site in sight! |
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Desperate for Diagnostics |
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Beyond the Limits! |
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| Klas Björck |
| Product Manager Relay |
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| No matter how well specified a test set is, it’s certain that users will find ways of pushing it to its limits and beyond. That was certainly the case with the high-current test equipment in use at the Diablo Canyon nuclear power plant in the USA – and addressing the problem wasn’t easy. |
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| Moulded case circuit breakers (MCCBs) play a key role in the operation of nuclear power plants, as was all too convincingly demonstrated when, around two years ago, the failure of an MCCB to trip led to a major incident at just such a plant. For this reason, the technicians at the PG&E (Pacific Gas and Electric) nuclear power plant in Diablo Canyon have always regularly tested the many hundreds of MCCBs used on their plant. |
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| Until recently, however, this was a complicated and costly task. Every MCCB had to be removed from the equipment in which it was being used and a temporary replacement fitted in its place. The unit to be tested then had to be taken to an electrical workshop where the test equipment was located, a process that involved time-consuming security check-in/check-out procedures. |
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| While looking for a more efficient way of carrying out MCCB testing, the PG&E maintenance team realised that by using a Megger ODEN portable high-current test set, they could take the test equipment to the MCCBs, rather than bringing the MCCBs to the test equipment. This meant that the MCCBs could be tested in situ, making the testing process far less time consuming and costly. |
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| And so it proved, except that during the first year of operations the test sets failed twice, once in the spring and once in the autumn. This was bad enough, but the situation was made worse when enquiries revealed that these were the only times of year that the test sets were being used! To gain a better understanding of the problem, Megger’s engineers carried out further investigations, which showed that PG&E was subjecting the test equipment to extreme operating conditions. |
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| In order to minimise the disruption caused by testing the MCCBs, the PG&E technicians scheduled the work to take place over just four days, during which time the test equipment was operated continuously, twenty four hours a day. This duty was well beyond the original design parameters for the ODEN test sets. |
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| At this point, it would have been easy to advise the PG&E that it was using the test equipment improperly, and to walk away from the problem. Instead, Megger saw the issue as an opportunity to improve the design of its products, and to make them a better fit for the requirements of all its customers, no matter how demanding those requirements might be. |
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| Unfortunately, it proved impossible to replicate in the development laboratory the severe conditions that provoked the equipment failures. Nevertheless, sufficient data was gathered during the laboratory work to suggest a possible solution. This was discussed in detail with the PG&E technicians who concurred with the conclusions, and agreed that the modified equipment would be used during the next scheduled period of testing. |
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| During this testing, a top-level engineer from Megger was present on site at all times, to provide PG&E with a lifeline should a further failure occur. The services of the engineer were not, however, required – the equipment performed faultlessly. Nevertheless, at the end of the testing period, it was returned to the development laboratory where it was examined in detail to ensure that there was no concealed damage or degradation. |
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| During the upgrade process for the instruments, the opportunity was taken to incorporate a further modification to allow direct operation from a 480 V 60 Hz supply. This |
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| meant that PG&E no longer needed to use a step-down transformer that weighed around 50 kg and cost several hundred dollars. While these are clearly significant benefits for PG&E, it’s worth noting that the upgrades are now included as standard in all new ODEN test sets. |
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| By responding positively to very specific customer requirements, users of the ODEN test sets will now benefit from product enhancements. |
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| PG&E is delighted with the outcome of this project. Before it switched to in-situ testing of MCCBs, testing took seven days and involved 840 man-hours of work. With the new test equipment, testing is completed in four days and requires less than 400 manhours of work. In addition, the new testing regime is helping to avoid breakers being replaced unnecessarily. The total savings amount to over $30,000 per year, which means that the test equipment easily covered its costs in the first year of use. |
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| Despite these very successful outcomes, development work on the ODEN test set continues. A new high current test probe that is well suited for in-situ MCCB testing has recently been made available, as has a software application that will capture every single test result form the test set, as required by current NRC (Nuclear Regulatory Commission) regulations. |
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| When this software is used, the test set automatically dumps the test results to the PC at every trip. When the test is completed, the data can be synchronised with a PC and imported to Excel or Word for reporting. |
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| Manufacturers and users alike abhor equipment failures, even if they can be justified because the equipment is being pushed beyond its design limits. As has been shown however, a positive reaction to such failures can guide manufacturers toward product improvements that will ultimately benefit all users. |
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A superior site in sight! |
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| Keith Johnson |
| Web Developer |
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| Not long ago, for most engineers, finding product and application information usually meant searching their company’s technical library, a task that could easily take hours. Now, of course, they turn to the Internet, and expect an answer in seconds! |
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| To ensure that this fast response is exactly what they get when they visit the Megger website, it has been completely overhauled and upgraded. The new site is hosted on a much more powerful server and the bandwidth of the server’s Internet connection has also been greatly increased. Users will, therefore, enjoy a faster response, even at busy times, which will be especially noticeable when they are downloading large files like catalogues and user guides. |
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| The site search facilities have also been upgraded, making it quicker and easier than ever for users to find exactly what they need. An improved user interface, which is more intuitive in operation, and enhanced multilingual capabilities, including support for Simplified Chinese, complete the list of readily apparent new features. |
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| But under the surface, much more has changed to pave the way for further developments in the near future. For example, the new systems provide extended support for the so-called Web 2.0 technologies. These will ultimately allow users to interact much more closely with the site, changing it from a largely one-way communication channel into a fully fledged two-way communication resource. Media streaming capabilities for video content have also been added. |
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| The new web server is tightly integrated with Megger’s back-office systems, which will ultimately make it possible for users to directly access a wide range of invaluable information including, for example, the up-to-date status of orders for calibration and repair work. |
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| Megger’s new website has been designed from the outset to provide all users with a useful and readily accessible resource. Many of its innovative features are already operational and there are many more to come. Take a look at www.megger.com/uk where we will be piloting concepts for all of Megger’s web sites, and don’t forget to check back often for further enhancements! |
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Desperate for Diagnostics |
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| Alexey Klimov |
| Managing Director, Pergam |
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| There’s a big problem with Russia’s electricity supply infrastructure, says Alexey Klimov, Managing Director of Pergam Engineering, one of that country’s most successful suppliers of services and equipment for electrical and non-destructive testing. And the problem is that almost all of the generating, transmission and distribution plant is decades old, and its present condition is largely unknown. |
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| Perhaps unsurprisingly, history is to blame. In the Soviet era, all of the plant was government owned. Then, in 1987, came the period of perestroika – literally, restructuring – when ownership, by and large, passed to public-private partnerships. A key characteristic of the public-private era was lack of investment. Very little new plant was installed, and existing plant was poorly maintained. |
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| In more recent times, ownership of the electricity supply infrastructure has changed yet again, and most of it – except for Russia’s national grid – is now in the hands of private organisations. These organisations, which include many multinational energy supply companies, are finding that they have little in the way of dependable information about the plant they have inherited, and in particular about its current condition and reliability. |
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| To address this issue, there is a desperate need for diagnostic and testing services of the type provided by Pergam Engineering. The magnitude and urgency of this need was, unfortunately, emphasised by the accident that occurred on 17th August 2009 at Russia’s largest hydroelectric power plant – the Sayano-Shushenskaya plant in southern Siberia, operated by RusHydro. In essence, an explosion occurred in the room where the turbines are located, which destroyed the walls and ceiling of the room. One of the plant’s ten turbines was totally destroyed, two were partly destroyed and three others were damaged. At least 70 people lost their lives and the total cost of the accident is expected to be around €1 billion. |
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| While detailed investigations into the cause of the explosion are still ongoing, first indications are that poor maintenance was, at the very least, a contributory factor. It also seems likely that the protective relay systems that might have helped to minimise the extent of the problem failed to operate correctly, something which could probably have been avoided had they been tested regularly. |
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| Alexey Klimov notes that, despite uncertain condition of much of Russia’s existing electricity supply infrastructure, there is little to suggest that equipment replacement on a |
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| large scale will take place in the foreseeable future. Instead, the emphasis is still firmly on repair and refurbishment. |
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| A notable exception to this is three large nuclear power stations that are currently under construction. In fact, despite the country’s extensive oil, gas and coal resources, Russia’s future energy policy is biased toward the expansion of its nuclear capacity. At present, around 17% of the country’s electrical energy is derived from nuclear sources but the Federal Atomic Energy Agency (Rosatom) has announced targets for increasing this to 23% by 2020 and 25% by 2030. |
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| In contrast, Alexey Klimov reports that there is at present little interest in renewable energy sources such as wind generation or wave power. He suggests that this is due to Russia’s abundant fuel resources and energy prices that remain very low, factors that diminish the attractions and the economic case for green generation. Nevertheless, he notes that there is growing concern over emissions, greenhouse gases and global warming, so it is possible that attitudes may change. |
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| In summary, Alexey Klimov sees the Russian power generation and distribution sector as dynamic and reasonably well funded, even though its emphasis will for a long time, be largely on prolonging the life of existing plant rather than investing in new. |
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| He also notes that Russia is closely aligned with Europe in many ways – its electrical standards are, for example, modelled on those of the IEC rather than those of the American IEEE – but that its energy policy is unique, particular with regard to its emphasis on nuclear expansion rather than investment in renewable energy sources. |
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