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Published by Megger
Sep 2010 |
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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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Ground test auto |
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The story of Multi-Amp |
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The EGIL has landed! |
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Norwegian Blues |
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Ground test auto |
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| Paul Swinerd |
| Product Manager |
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| For many years, stakeless or clamp-on testing has been accepted as an established method of testing earth system resistance, and is now included in the German standard VDE 0100-600:2008 (appendix B3). This method has a number of real user benefits, in particular not having to disconnect the electrode under test, increased user safety and huge savings in time and aggravation. |
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| However, many users are failing to enjoy the benefits of stakeless testing, and that's mainly down to two main issues. Firstly many potential users do not fully understand the testing technique, and avoid it; secondly many people have found some problems when testing, resulting in a number of concerns. |
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| The first issue is easy to solve when you know where to go. You can find forums and micro-sites such as the one at www.megger.com/det to help with many of these problems, or you could phone one of Megger's regional technical support offices. Easy, if you have time to stop your work and do the research! |
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| The second issue is not so easily fixed. Problems experienced in actual testing are often caused by the abilities – or inadequacies - of the test equipment. Let's take a look at these concerns and see how we can eliminate or maybe get round them. |
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| For obvious reasons, most users have safety as their primary concern. In substation environments, the stakeless testing method may be the only method available to you. But what happens if you are holding the instrument when a massive fault produces a huge transient on the cable that you happen to be clamped around? This could also be a concern to users testing lightning protection; there can be a sudden lightning bolt that could kill you. The other and maybe less obvious hazard will present itself if, for whatever reason, the user has to disconnect one of the electrodes that is being tested. If there is too much current flowing down the electrode when it is disconnected, it will quickly turn into a hazardous voltage. |
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| What's the answer? Firstly, choose an instrument with the highest IEC safety category; it will have the best isolation between your hand and what ever you are clamped around. Secondly choose one that has a current measuring range, then you can measure whether there is a hazardous level of current flowing before you disconnect. |
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| If you work in a sub-station environment you may also have another concern which many users have no doubt experienced. Noise interference in the form of leakage currents flowing through the electrode under test can result in varying readings or in some cases actually prevent testing completely. In this case the solution is to select an instrument with the highest noise current immunity you can find. |
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| Many electrodes are in difficult to access locations; in boxes, pits or are just difficult to reach. What can you do in these situations? Your choice of instrument will directly influence your success in such situations. Choosing a clamp with a large jaw capacity is not just about the size of cable it can clamp around, it will also provide a better angle of approach. Also, look at the instrument's body length. The longer it is, the more instrument there is to accommodate down an electrode pit. Another feature that will help with access is to have a jaw head that is slimmer in profile, and a backlit display will surely help too, especially in substation basements. |
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| Let's recap and talk about clamp capacity. The challenge isn't always to clamp around the large size of cables, as there may also be a requirement to clamp around flat earth tapes. In many cases these flat tapes have to be pried from walls, so a smaller section clamp will help. However these tapes are getting bigger, and in some locations such as on earth systems used on ~400 kV supplies they can be 50 mm x 10 mm. That really limits your choice of how to test. |
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| The other burning issue is reliability. Earth testing clamps get used in tough environments and are often used in remote locations such as on utility pole electrodes. Many instruments have interlocking laminations (or interlocking teeth as they are often referred to). These 'teeth' are easily damaged and collect dirt which can either produce errors in measurement, or render the instrument useless and awaiting a trip to the repair shop. The answer is to use an instrument with smooth mating jaw surfaces. That sounds obvious but it is often overlooked. |
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| Also carefully check the instrument's battery life and check that there are readily available batteries in the location where you will be working. In a remote area, this could be a real concern to the user. |
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| Stakeless testing has real advantages and specifying the right instrument will really help get the best out of the method. |
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| Megger has just launched a new range stakeless testers specifically designed to overcome the problems outlined in this article. The new DET14C and DET24C have these new features: |
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 CATIV 600 V safety, with 8 kV of transient isolation |
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| Auto hazardous current warning even on the resistance range, giving you peace of mind, and no need to worry about remembering to measure it |
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| Auto noise filter to provide the best of immunity to noise current |
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| Unique elliptical shape head with a 37 mm x 55 mm capacity and slim profile which provides excellent access and can clamp around a 50 mm x 10 mm earth tape |
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| Smooth mating jaw surfaces which are easy to clean and have no teeth to bend |
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| Huge battery life from readily available AA batteries, which last 24 hours with a 25 Ω load |
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| Pre-hold function which automatically initiates a test when clamped around an electrode, then holds the reading for reviewing when removed from the electrode. |
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| Backlit display |
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| With all these ground test auto functions, you could find your worst problems just go away! |
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The story of Multi-Amp |
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| Bruce Buxkemper |
| VP, Megger Dallas |
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| While Megger today is a single organization that supplies one of the world's widest and most innovative ranges of portable electrical test equipment and measuring instruments, it continues to benefit greatly from the unrivalled expertise it has acquired from the many businesses that have, over the years, joined the Megger family. One of these is Multi-Amp, and here we provide a brief insight into the fascinating history of this company. |
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| Multi-Amp was founded in 1951 by a group of utility engineers who realised that there was a need for reliable portable instruments for testing at high currents. This guided the choice of company name – its products would test at multiple amps! Among its early offerings was a very popular, and for the time very compact, high current test set designated the MS-1, which was widely used by heavy industrial companies for testing motor overload relays and small circuit breakers. |
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| Multi-Amp also introduced primary injection test sets with current ratings as high as 100,000 A. These units were used principally for testing large low voltage circuit breakers. |
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| Arguably an even more significant factor in the success of Multi-Amp was its pioneering work in the field of protective relay testing. Until the middle of the 1960s, few utilities recognised the importance of such testing but then things changed literally overnight. On November 5, 1965 a huge power blackout left 30 million consumers in parts of the North-eastern United States and Canada without electricity. The initial cause of the problem was a protective relay that failed to trip. Suddenly protective relay testing moved to centre stage. |
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| At that time, Multi-Amp was under the guidance of Ed Redlhammer, who was an evangelist for better relay testing and maintenance. Most relay testing in those days was done using a variety of variable autotransformers, resistive loads, ammeters, voltmeters and other sundry equipment. As a result, it often took longer to set up the equipment than to carry out the test itself. Ed's insight was to produce a dedicated relay test set that would eliminate the need to use many separate items of equipment, so that the test technician or engineer could spend more time testing, calibrating and servicing the relays, and a lot less time in setting up and taking down the test equipment. |
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| This approach meant that Multi-Amp was well placed to respond to the sudden increase in demand for protective relay testing after the blackout with its SR-51 protective relay test set. Taking advantage of successive advances in technology, this evolved in several stages into the SR-76, |
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| The Multi-Amp® PULSAR® Universal Protective Relay Test System represented the next generation in protective relay testing. |
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| and subsequently, the SR-90, which was introduced in 1990 and finally discontinued only this year. Technology moves on, and even the best of instrument designs eventually reach the end of their life! |
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| In the late 1970s, the pioneering SR range was complemented by the company's first solid state relay test set, the SSR-78. This evolved into the EPOCH series of protective relay test sets in the 1980s, laying the foundations for the development of Megger's latest MPRT and SMRT testers. At every stage, the development process was customer led. Multi-Amp was then – as Megger is today – committed to talking to its customers, discovering their needs, and then applying its technical expertise to meet those needs efficiently and cost-effectively. |
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| After Ed Redlhammer retired as president of Multi-Amp in the late 1980s, his role was taken over by Ruben Esquivel, who had fled Cuba when the Castro regime came to power. He joined the company as an assembler wiring high-current test sets, and went to night school to earn his electrical engineering degree. He then continued his education to earn an MBA, and ultimately became one of the co-owners of Multi-Amp. |
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| He retained his share of the ownership until the company joined, among others, AVO and Biddle to become part of the present-day Megger organisation. This gave the members of the Multi-Amp team access to the resources they needed to drive their ambitious development programme forward, so that the company could continue to produce equipment that would meet the ever-increasing expectations of end users. |
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| Megger continues to uphold the proud traditions established by Multi-Amp, and to this day retains its position as a leading innovator and manufacturer of high current test equipment and versatile protective relay test sets. |
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The EGIL has landed! |
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| Romain Douib |
| Product Marketing Manager |
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| Featuring compact construction and straightforward operation, Megger's latest EGIL circuit breaker analyser is suitable for testing timing and travel on all breakers that have a single interrupter per phase. In addition, when used in conjunction with the SDRM option and the new SDRM201 accessory, the instrument can also be used to carry out static and dynamic resistance measurements. |
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| Although the EGIL is available at a very attractive price, no compromises have been made on its versatility or performance. |
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| It is, therefore, an ideal choice for operators of small power plants and for the maintenance of simple circuit breakers by power distribution utilities. |
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| To aid ease and speed of use, the EGIL has a built-in sequencer that automatically runs the selected breaker operating sequence while making the appropriate measurements and recording the results. In addition, menu-driven procedures invoke sensible default settings, thereby eliminating the need for time-consuming pre-setting. Megger's EGIL test set offers three timing channels for the circuit breaker main contacts. Main contacts and pre-insertion resistor contacts can be timed on the same channel, with the results recorded graphically and numerically on the integral printed. Results are also shown numerically on the instrument's large easy-to-read display. |
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| Two additional galvanically isolated timing channels are provided for auxiliary contacts. In addition, an analogue channel is available as an option. While primarily intended for monitoring contact motion, this channel also finds many other applications. |
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| For EGIL test sets that have the SDRM option installed, the SDRM201 module extends the facilities to allow accurate resistance measurements to be made on circuit breaker contacts and other low resistance devices. When used with the test leads provided, the SDRM201 is capable of supplying an instantaneous current of 200 A DC, falling to 140 A after one second. Multiple tests can be run with only a short waiting time between them. |
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| Used in conjunction with the SDRM201, the EGIL test set supports dynamic resistance measurement from 0 to 32 mΩ, and static resistance measurement from 0 to 2 mΩ. The inaccuracy of static resistance measurements is 2% ±2 µΩ or better. |
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| To complement the latest models of its EGIL circuit breaker analyser, Megger has introduced a new version – R03A – of its CABA Win computer-aided breaker analysis software. Designed to run under Microsoft Windows on a standard PC, this adds full support for static and dynamic resistance measurements, new test plans for applications where the EGIL is used with the SDRM201, and 19 new timing parameters for multiple operations. |
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Norwegian Blues |
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| Per Vågsether |
| Sales Engineer, Tormatic AS |
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| Per Vågsether, Sales Engineer at Tormatic AS, a leading supplier of equipment and consultancy services to Norway's power industry, provides an overview of the Norwegian energy supply sector, and explains how global warming is creating problems that are giving electrical utilities a definite attack of the blues. |
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| Hydro electric power |
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| As might be expected in such a mountainous country, most of Norway's electricity is generated by hydroelectric plant. In fact, Statkraft, a power utility which is wholly owned by the Norwegian government and which supplies much of the country's power, is Europe's largest renewable energy company. |
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| In recent times Statkraft has diversified its operations, partly for reasons that will become clear later in this article, and now, in addition to hydroelectric power, it is also involved with wind power, gas power, solar power and biopower. |
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| Norway power stations in 2008 |
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| In 2008, the latest year for which figures are currently available, Norway had a total of 737 power stations, of which 691 were hydroelectric, 29 thermal and 17 wind power. The total installed generating capacity was almost 31 GW. During the year, Norway produced 142 TWh of electricity, almost all of which was consumed domestically, one of the largest users being the aluminium industry that developed in the country principally because of the availability of cheap electricity. |
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| Norway has an open electricity market and it routinely imports and exports energy over direct power links with countries that include Sweden, Denmark, Germany and the Netherlands. Since Norway, with its large hydroelectric power base can, for most of the time, generate electricity at lower cost than its neighbours, energy exports predominate over imports. In 2008, for example, it exported 17.3 TWh and imported only 3.4 TWh. |
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| Deregulation |
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| Norway's power distribution companies were deregulated and privatised a few years ago. Consumers are, however, still tied to their local distribution companies in an arrangement the Norwegian Ministry of Petroleum and Energy describes as “monopoly regulation”, which includes an income cap for each network company. |
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| Monopoly regulation is intended to safeguard consumer rights while ensuring a well functioning power market and that the grid is developed and managed efficiently. The regulatory system has recently been fine-tuned to provide enhanced incentives for investment and to make it more certain that the benefits of efficiency improvements will be passed to the customer. |
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| In spite of this arrangement, the privatisation of the power companies and the recent acquisition of some of them by foreign organisations have brought mixed benefits. These developments are certainly working well for the owners of the companies, but not necessarily quite as well for energy users, who are seeing higher prices with no perceptible improvement in performance. |
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| These criticisms may, however, be a little unfair as Norway's energy prices are still among the lowest in Europe, and the country's transmission network already has one of Europe's highest uptimes. |
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| The effect of global warming |
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| There is, however, a much bigger cloud on the horizon, one that is certainly significant enough to create a distinct feeling of “the blues” among energy producers and consumers alike. This problem is that the amount of energy available from hydro-electric power plants, on which the country is highly dependent, is falling. And it is by no means certain when, or even if, this decline will end. |
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| It's not hard to find the reasons for this. Hydroelectric generation depends on water flow and, in Norway's case, most of the water comes from melting snow. Because of global warming, however, much less snow is now falling, so there is much less melt water, which means significantly reduced generating capacity. With these facts in mind, it's not hard to see why ecology and environmental protection are currently such hot topics in Norway. |
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| Of course, the utility companies are responding to this issue, typically by putting research efforts into alternative green energy sources, such as wind power and wavepower, the latter being a particularly attractive option given the country's very long coastline. |
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| Norway has an ambitious plan to cut greenhouse gases |
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| There's a very long way to go before these sources make a significant contribution, but it is worth noting that Norway was the first country to generate electricity commercially with seabed tidal power, when a prototype 300 kW plant was brought into service near Hammerfest late in 2003. |
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| Wind power |
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| The utilisation of wind power in the country is considerably more advanced, with some 913 GWh of electricity obtained from this source in 2008. Nevertheless, there are concerns about building more on-shore wind farms, not least because, in spite of their excellent carbon footprint, they are thought to adversely affect the environment in other ways, such as disrupting the breeding of eagles. Offshore wind farms are seen as a more attractive proposition, in spite of the higher costs and the technical difficulties involved. |
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| Another option under consideration is the building of new gas-fired thermal stations, which initially seems logical as Norway has access to large reserves of natural gas in the North Sea. There are very great environmental concerns with this course of action, however, because of the CO2 emissions that are almost unavoidably associated with hydrocarbon fuels like natural gas. |
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| For this reason, there are many who suggest that the natural gas should be seen as an export opportunity and sold to other countries like the UK, where gas-fired power stations are already in widespread use. Unfortunately, this does seem rather like transferring the problem to a neighbour, rather than genuinely solving it. |
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| Ambitious plan to cut greenhouse gases |
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| However challenging they may be, these issues will have to be addressed promptly as, in January 2008, the Norwegian government set itself what it describes as “the world's most ambitious target for cutting greenhouse gas emissions” – this is to make the country as a whole carbon neutral by 2030. |
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| The full details of how this is going to be achieved remain a little sketchy, but the plan is not only to reduce CO2 emissions at home, but also to invest up to 3 billion Norwegian Kroner (about US$ 0.5 billion) per year to combat deforestation in developing countries and thereby gain carbon credits. |
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| For decades, Norway has enjoyed cheap “green” electric power, and the country is still well blessed with renewable and non-renewable energy resources. Nevertheless, as we've seen, there are major issues to be addressed over the next few years and as a result, this will undoubtedly be a very interesting and challenging period for all of those involved in the country's energy sector. |
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News 