Issue 1 2024 Magazine VIBRO-ACOUSTIC MEASUREMENT FOR ON-LOAD TAP CHANGERS
In this edition, we will take you on a journey through the fascinating world of technology and innovation. We will present you with a selection of articles that provide insight into our latest developments and shed light on their practical relevance. We begin with an analysis of the longterm collective challenges that we face. The article on page 26 delves into current developments in the energy sector and associated challenges. You will gain valuable insights into this complex topic and learn how innovative solutions can help avoid future supply shortages. Next, we have an article written in collaboration with our client, BASF. It explores how one of the world’s largest chemical companies uses data to optimize processes while increasing sustainability and efficiency. A fascinating behind-the-scenes look demonstrates how data analysis and sustainability can go hand in hand. Another highlight is the report on developing a new measurement method for Capacitor Voltage Transformers. On page 32, you will discover how precision in electrical engineering not only contributes to efficiency but also enhances safety. Furthermore, explore the importance of certifications by using the example of the BSI certificate we recently received for our StationGuard intrusion detection system. Learn how a small seal holds special significance for quality assurance and why it means more to us than just a certificate. In summary, each of these stories is linked by a central theme: innovation and its influence on our future. Whether it’s challenges in service and repair requests, the transformative power of data usage, precision in measurement technology, or the significance of certifications – all these articles illuminate how technological advancements and innovative strategies can help us collectively overcome the challenges of tomorrow. I hope this edition of the OMICRON Magazine will enrich and inspire you. Your feedback always helps us improve new editions – please share your thoughts with me. I look forward to hearing from you. Yours sincerely, Lia Thum Editor in Chief, OMICRON Magazine OMICRON electronics GmbH, Oberes Ried 1, 6833 Klaus (AT) OMICRON electronics GmbH up! consulting, Industriering 10, 9491 Ruggell (FL) OMICRON electronics GmbH, OBRE (p. 4, 6–8), BASF (p. 4, 10–13), iStock.com (p. 4–5, 22, 26–28, 37–39, 42), TEİAŞ Turkish Electricity (p. 23–25), Schluchseewerk AG (p. 32–33), LTD Tranfiber-Service (p. 36), CIGRE (p. 43) magazine@omicronenergy.com Publisher Responsible for content Editorial team and implementation Picture credits E-mail to the editorial team DEAR READERS, 2
Magazine | Issue 1 2024 «Imagination is more important than knowledge, for knowledge is limited, whereas imagination embraces the entire world, stimulates progress, and gives life to evolution.» Albert Einstein 3
TABLE OF CONTENTS 9 ASH1 – highest flexibility for optical scanning heads Our new adapter that connects optical scanning heads through binary inputs. 10 Ready for the challenges of a zero-emission future In collaboration with OMICRON, BASF shows how to successfully introduce a new data and testing strategy. 20 Our cybersecurity system shines with distinction OMICRON receives security certificate from the BSI. 14 A test set ballet Service Hubs open up around the world. 22 How to verify suspected insulation faults in power transformers 18 See and understand Get a better overview with CPOL3 for wiring tests. 6 Good vibrations Listen to your on-load tap changer, it may be trying to tell you something. 4
Magazine | Issue 1 2024 KNOWLEDGE SUPPORT INNOVATION QUALITY 30 Circuit breaker testing around the world How are circuit breakers being tested on different continents? 32 A blackout is followed by a black start 36 On site: OMICRON in Georgia Ivane Sachaleli from LTD Tranfiber-Service gives us his insight into the power sector. 26 No shortage of shortages Impact of the component crisis on the energy sector. 38 Determining the C-divider capacitances of a Capacitor Voltage Transformer Developing a new measurement method. 29 What’s new in Test Universe 4.40? Greater scope for your tests. 42 A worthwhile commitment Why engaging within electrical engineering societies makes sense. 5
GOOD VIBRATIONS Listen to your on-load tap changer, it may be trying to tell you something. The on-load tap changer (OLTC) is an essential component of a power transformer that helps maintain a stable voltage level within the electrical grid. It adjusts the transformer turns ratio, which regulates the system voltage. Various diagnostic tools are available to assess the static and dynamic characteristics of the tap-changer. While a DC winding resistance measurement can reveal wear and tear of the main contacts, the dynamic resistance measurement is sensitive to timing changes and current interruptions during the switching operation. The vibro-acoustic measurement (VAM) is a new tool in the diagnostic toolbox that records the vibrations produced during switching operations. This means that all the OLTCs’ components that create a certain vibration level can be analyzed and evaluated. It’s even possible to conduct an in-depth condition assessment by combining it with our well-established dynamic resistance measurement (DRM). The best results are achievable when the VAM and DRM readings are compared with reference data, either from the same unit or a comparable sister unit. 6
Magazine | Issue 1 2024 VAM signals are obtained using magnetically mounted sensors installed on the transformer tank. This connection technique allows the operator to record vibration signals while the transformer remains in service. Consequently, potential changes in the OLTCs’ mechanical integrity can be detected early between maintenance cycles without an outage. By doing this, the VAM can help prioritize individual units for the maintenance schedule. Paweł Molenda is a member of the board and deputy technical director of OBRE Poland. He performs on-site transformer diagnostics and gives technical advice in the transformer and HV equipment fields. He shared the insight he gained when he used the TESTRANO 600 and the VAM1 during his maintenance work on various on-load tap changers. Along with Tomasz Bednarczyk (Application engineer at OMICRON), Pawel and his team conducted several vibro-acoustic measurements to gain more profound knowledge about the OLTCs’ condition. Pawel, what is your typical testing scope for power transformers? Paweł Molenda: The scope and purpose of the test must be tailored to the client. We conduct on-site measurements in the periodic, post-installation, and post-failure measurement fields as part of our measurement activities. This includes testing the insulation state using polarization methods and measuring partial discharge using electric and acoustic methods. To summarize, we offer our clients all types of diagnostic measurements, from basic electrical tests to in-depth condition assessments. We perform measurements according to IEC and IEEE standards and follow customer instructions according to their requirements. «Vibro-acoustic measurements are a good method for initial tap-changer diagnostics that provide a quick and cost- effective initial assessment.» Paweł Molenda, Deputy technical director, OBRE Tomasz Bednarczyk, Application Engineer, OMICRON 7
What are the typical maintenance activities you conduct on OLTCs to ensure they function properly and their lifespan is prolonged? OLTC assessments are based on a DRM measurement and internal inspection of the diverter switch inserts. We adopt the appropriate diagnostic procedures depending on the number of OLTC switchings. First, we perform oscillographic measurements (DRM). Next, we set up an internal inspection for the tap-changer head, check the main and auxiliary contacts’ quality and the springs. Finally, we perform oscillographic measurements again to ensure the asset functions correctly. Thanks to these measurements, we can adjust the maintenance scope to increase the lifespan of the OLTC. How much experience do you have with dynamic resistance (DRM) and vibro-acoustic measurements (VAM) on OLTCs? We have performed oscillographic measurements for 20 years. In addition to that, we have been conducting OLTC vibro-acoustic measurements for a year now. We often used our MT3 device for this type of measurement. For some years now, we have only been using OMICRON measuring devices, and the recent addition of OLTC vibro-acoustics and our cooperation with OMICRON has enhanced our experience. What are the benefits and limitations of these methods? Measurements are the first step in assessing the technical condition of the on-load tap changer. The benefit of this is that it provides a quick and cost-effective initial assessment of the asset’s condition. However, correctly evaluating the on-load tap changer is only possible after the condition of the contacts and the OLTCs’ mechanism have undergone internal inspection and visual checks. What stages of the maintenance cycle do you apply these methods to, and how do you interpret and analyze the results? Typically, they are performed before and after maintenance work, but sometimes, they can be performed more frequently between inspection intervals and electrical measurements. We then compare our results with our customers’ standards, norms, similar switches, and experience. Does measuring OLTCs help facilitate the maintenance and maintenance schedule of the unit? Absolutely. OLTC measurements help predict the operation time and repairs for the tap changer, while the online vibro-acoustic measurement is a quick method for initial tap-changer diagnostics. These methods provide a quick and cost-effective initial assessment of the OLTCs’ condition, which can help prevent costly downtime and repairs in the future. In some cases, Diverter Switch Insert (DSI) defects can be diagnosed earlier between transformer inspections, and vibro-acoustics can help assess the OLTCs’ technical condition much earlier without taking the transformer out of service and conducting a costly inspection. If the method and analysis of the results are refined, online vibro-acoustic measurements offer excellent opportunities for scheduling the OLTC for maintenance in the future. Thanks for the interview. 8
Magazine | Issue 1 2024 ENHANCE YOUR DEVICE ASH1 allows you to connect an optical scanning head for relay testing to devices previously unable to do so by using binary inputs. For example, you can now use a COMPANO 100 to convert the LED indications from protection relays into binary signals and use them in test sequences, e. g., for assessments or trigger conditions. Using the COMPANO 100 as a battery-powered and portable device combined with the OSH 256R, a universally mountable optical scanning head for relay testing, is the ideal choice for portable and flexible testing. BECOME MORE EFFICIENT ASH1 allows you to connect more than one scanning head for meter testing to the binary inputs of your test set, such as the CMC 430. This makes testing more efficient because you can count active and reactive energy pulses without interrupting the test to change the scanning head position. To equip you with the proper scanning head for your meter test applications, we offer you three different sets for counting the optical LED pulses of digital meters or the rotor marks of electromechanical meters. omicron.energy/ahs1 Optical scanning heads are usually used for counting optical energy pulses during energy meter testing with a test set like our CMC or something similar. Scanning heads can also read status information from protection relays indicated by LEDs and convert them to binary signals for testing. The following examples illustrate how you can benefit from the ASH1 adapter and its new possibilities. ASH1 adapter OSH 256R mounted on a protection relay ASH1 – HIGHEST FLEXIBILITY FOR OPTICAL SCANNING HEADS Our new adapter that connects optical scanning heads through binary inputs. 9
READY FOR THE CHALLENGES OF A ZERO-EMISSION FUTURE In collaboration with OMICRON, BASF shows how to successfully introduce a new data and testing strategy. 10
Magazine | Issue 1 2024 The BASF Ludwigshafen site is the largest integrated chemical complex in the world. It spans some 8 km2|3 mi2 and has around 39,000 employees. As well as being connected to the Amprion grid, the site has three power plants with a total capacity of approx. one gigawatt. The entire site currently requires around 6 terawatt hours of energy per year and an average electrical capacity of 750 megawatts at a power density of approx. 100 MW/km2 | 40 MW/mi2. The power supply for the complex comprises: › >20 substations in the transmission grid › >160 substations in the distribution grid › >4,900 feeders › >6,400 protection relays Various device generations, manufacturers, and types, as well as the use of different protection concepts add to what is already a complex situation. The effort involved in maintaining the entire infrastructure is equally complex and challenging. However, the sheer scale of it also offers enormous potential for optimization in terms of the testing strategy and processes. In an effort to take the existing tasks in the area of protection technology to a new level using the resources available, Svenja Rogalski, Christian Schumacher, and his team have analyzed the situation in detail and embarked on an ambitious project. The project team has worked with us on this basis to develop a new data and testing strategy. The goals were clear: › On the one hand, the team wanted to establish a basis for higher data and test quality in order to improve the efficiency of the resources used. › On the other hand, they also focused on enabling troubleshooting and network expansion for the upcoming energy transformation with the existing team. The strategy revolves around our data management solution ADMO, which enables the straightforward management of assets, configurations, test templates, and test results while also ensuring their quality. No transformation is without its challenges The situation described above is just the starting point, however. BASF has set itself the company-wide goal of reducing its greenhouse gas emissions to net zero over the coming decades. To achieve this goal, the electrical capacity needs to be doubled to an average of 1.5 gigawatts. This poses challenges in terms of generation, transmission, and the distribution of the energy. This high demand is due to the technological changes required to reduce CO2 emissions. In the future, BASF will rely on industrial heat pumps and compressors, as well as electrically heated steam cracker furnaces. The carbon-neutral generation of hydrogen involves «The team really got locked in and was clearly enjoying protection testing again. The opportunity to help shape the new processes really motivated everyone.» Christian Schumacher, BASF 11
220 kV 220 kV Consumer 400 V, 500 V, 690 V Consumer Consumer 20 kV 10 kV 6 kV 110 kV BASF factory M M M M M M BASF power plants for own steam and electricity production two processes: water electrolysis and methane pyrolysis. The energy infrastructure needs to be expanded to accommodate this, and that requires new grids and substations to be established and the existing ones on the BASF site to be expanded. This involves the installation of a lot of additional assets, which not only need to be commissioned but also then have to be maintained every five years. Sequence of previous testing strategy During the preparation of the project, the team led by Christian Schumacher first examined the existing testing strategy. Previously, protection protocols were created using MS Excel templates that combined the setting sheet and the test report in one form. These MS Excel templates were populated semi-automatically using the asset database. All basic data, such as the protection device type, transformer ratio, etc., for the test case at hand, were checked and then typically sent to the testers, usually by email. The final protection protocol was then taken to the substation in printed form by the tester. The responsible team member performed the test, recorded the relevant values in the protection report, and then signed this report by hand. Finally, the document was scanned and stored in the asset database. The previous testing strategy had the following disadvantages: › The test teams responsible for the transmission and distribution grids had different test approaches. › The test points did not have tolerance specifications. › There were very few test points. › General uncertainties regarding the testing procedure and results among the protection testers › Incomplete quality assurance of the many manual work processes. › There was no reliable data source due to the lack of clear, standardized documentation. Setting course for the future Stefan Schöner and Michael Albert were on hand to advise the project team while developing the new testing strategy based on ADMO. The focus was on establishing standardized work processes across all test teams and, more generally, on improving data quality – two areas in which our data management system ADMO, in combination with Test Universe and CMC test devices, are ideally placed to support end users. Standardized protection tests have been and continue to be defined for the entire site as part of the ongoing project. These tests are easy to understand for all teams because detailed test templates and instructions are provided. They can also be compared one-to-one with tests that have already been carried out. Even after just a short amount of time, a lot of the insecurities that prevailed among the protection testers have eased. ADMO offers a central location where all necessary relay and test documents can be found in one place. There is also no longer any need to enter test results manually. They are automatically synchronized with the central ADMO database and securely stored as soon as the testers connect to the company network. Eliminating the Structure of the power grid at the Ludwigshafen site Feeding from the external transmission network 12
Magazine | Issue 1 2024 need for manual intervention improves the resulting data basis and makes the data analyses performed based on this data more meaningful. Going forward, the ability to compare data collected in a standardized way will also enable more informed statements to be made about the history and condition of the assets. The collaboration with external service providers has brought other benefits for BASF: › For both commissioning and maintenance tests, project data can be transmitted securely, in full, and in a traceable manner. › The specifications and the scope of the required tests can be clearly defined using the templates and reports. › Any changes are documented thoroughly and reliably. The development of a new testing strategy, like at BASF, always involves a certain amount of effort to start with. However, it very quickly generates significant benefits, particularly in terms of more efficient processes for the preparation, execution, and documentation of tests. Ready for phase 3 The implementation of the project has been divided into three phases. BASF has already successfully implemented phases 1 and 2 with us. The focus of these phases was on ascertaining the current situation, including the level of knowledge among staff, sharing knowledge, and developing the initial test templates. With our training on the basics of protection technology, the definition of a test specification, and our recommendations on testing strategies, we brought all protection testers up to the same level of knowledge. Following on from this, the next step was to develop test templates within several working groups. For the distribution grid, test templates were created for inverse-time overcurrent protection/definite-time overcurrent protection, line differential protection, and motor protection. For the transmission grid, templates are now available for distance protection, transformer differential protection, and busbar protection. In the current phase of the project – phase 3 – BASF is now pressing ahead independently with the implementation of the new testing strategy and including additional protection types and devices. Our experts are on hand and available to provide support as required in this phase too. Making protection testing fun again The excellent results demonstrated how motivated the working groups were to get locked in and make some changes. We were particularly pleased to see that by sharing our experience and knowledge, we were able to reduce insecurity in day-to-day work. According to Christian Schumacher, it is also clear that employees are enjoying protection testing again. Last but not least, thanks to the project and the use of ADMO, protection, testing, and parameterization data is now used with much greater awareness at BASF. Although the achievement of net zero may still be some way off, BASF is now well equipped to tackle the challenges ahead with its new data and testing strategy. 13
Magazine | Issue 1 2024 As the enormous entrance door of the OMICRON Service Hub in Klaus opens and slides upwards, it’s almost like watching a heavy stage curtain rising to reveal the set. The countless yellow boxes roll out onto the dance floor – disguised as a loading ramp – and take their positions. The choreographer of this test set ballet is Roman Novak, who, together with his team, is now setting off on a world tour with this show. When the very first OMICRON Service Hub opened at our head office in Klaus at the beginning of 2021, there was no orchestra to be heard, nor was anyone tapping out a rhythm with the familiar „and one-and-two-and-three …“. Yet the precision behind the planning and timing of all the processes undoubtedly resembled sophisticated choreography. Everything must be perfectly coordinated to ensure the entire process runs smoothly and efficiently. The aim of this project was to create a onestop shop for all our service and repair requests. In addition, the design of the hub and the lessons learned from this pilot project serve as a blueprint for our other sites. Now, almost three years later, the test phase is complete, and the Service Hub concept is being rolled out around the world. A TEST SET BALLET Service Hubs open up around the world. Focusing on service quality „One of our most important objectives in designing the Service Hubs was to be able to handle service requests faster and more efficiently. The hubs had to operate completely independently of our day-to-day business activities to achieve this. Even major companywide projects should have zero impact on the hubs so that our customers can always expect a consistently high level of service quality“, explained Roman, manager of the Service Hub in Klaus. „We operate autonomously. Besides all the technical aspects of our service activities, the team handles the entire process from beginning to end. From order clarification to logistics – regardless of whether the request is for a calibration, an adjustment, a repair, or an individual service call-out. We also handle callbacks ourselves. For example, a test set may arrive in the workshop without any error description. We then contact the customer directly to ensure that the test set is functioning again as soon as possible. From the time they arrive in the hub to their dispatch, test sets remain with us for an average of five days. Global standard, local service Targeted standardization is what allows us to provide such prompt service. Like a carefully planned stage performance, every service activity 14
«One of our most important objectives in designing the Service Hubs was to be able to handle service requests faster and more efficiently.» Roman Novak, Process Manager, OMICRON 15
follows a meticulously structured sequence. In addition to the processes, workplaces have been standardized as well. In every Service Hub across the globe, employees use the same infrastructure and equipment – the same tools, software, and, naturally, spare parts. Whether a team member is working in the Service Hub in Klaus, the Service Hub in Houston, which opened last year, or in one of our future hubs in Asia or Australia – they should always feel they’re working in a familiar environment. Apart from standardization, future sites also play a significant role in optimizing service times. For example, test sets no longer have to be returned to Klaus to be adjusted; they can be calibrated on-site. That’s why every Service Hub has climate-controlled rooms with multi-test towers. Networking the hubs Even though the Service Hubs operate autonomously, they remain closely linked. „The hubs are networked together so that a regular exchange of knowledge and ideas can occur. The benefit of this is that when a problem has been resolved at one site, all the others benefit from the experience without having to find solutions of their own.“ this is how Roman gives us a glimpse into the collaborative process between individual Service Hubs. „In summary, we can say that the pilot project in Klaus has been a resounding success, and the concept has proven itself with the opening of the Service Hub in Houston. We’re looking forward to opening additional sites and extending the reach of our high-level service quality.“ «In summary, we can say that the pilot project in Klaus has been a resounding success, and the concept has proven itself with the opening of the Service Hub in Houston.» Roman Novak, Process Manager, OMICRON 16
Magazine | Issue 1 2024 Service Hub backstage pass We’ve prepared a short Service Hub presentation video to give you an idea of what goes on behind the scenes at the Service Hub in Klaus. Scan the QR code to see what’s going on behind the curtain. omicron.energy/whatsup-at-service-hub 17
Wiring errors commonly cause protection system failures in power supply systems. Testing the wiring during commissioning and after maintenance work is essential for preventing the danger that wiring errors can cause. This is a time-consuming process, as transformer wiring, trip signals, interlocks, remote control technology, and much more soon add up to hundreds of connections within installations. CPOL2 already provides a tried-and-tested, flexible procedure for testing transformer wiring, which – in contrast to the frequently used “battery method” – does not magnetize current transformers due to the DC-free saw-tooth signal. However, as the trend toward more and more protection and remote-control technology continues, the complexity of wiring and challenges are rising along with it. We have developed our CPOL3 polarity checker to assist you in these areas. Like the CPOL2, the device can detect saw-tooth polarity test signals, and now, it can also detect AC and DC signals. Furthermore, CPOL3 even has some additional new features that surpass the proven functionality of its predecessor. SEE AND UNDERSTAND Get a better overview with CPOL3 for wiring tests. Indication when the test signal polarity is correct “Oscilloscope” mode for displaying the signal waveform Indication when the test signal polarity is incorrect Spectrum mode (FFT) for detecting coupled signals 18
Magazine | Issue 1 2024 New features › Displays the True RMS voltage as well as the polarity › “Oscilloscope” mode for displaying the signal waveform › Mode with low input impedance (LoZ) to suppress coupled signals › Viewing angle independent OLED display with high contrast for optimum readability › CPOL3 already displays phase information for future testing software Highly versatile You can combine several aspects of a wiring test using CPOL3 in conjunction with one of our test sets, such as COMPANO 100, CMC 353, or CMC 356: 1 During the test, introduce a saw-tooth test signal on the primary side A or the secondary side B of the current or voltage transformer. Primary injection is possible as current and voltage transformers transfer this signal waveform. 2 If the polarity is correct, the CPLO3 displays a green happy face. You can also display the signal in “oscilloscope” mode, and you will then see a saw tooth that quickly rises and slowly falls. X At this position on the secondary side, there is a wiring error. 3 The wiring error causes a polarity reversal, and CPOL3 displays a sad red face. You can also recognize the incorrect polarity from the reversed signal in “oscilloscope” mode. 4 In addition to the polarity, CPOL3 also shows you the measured voltage on the display. The nearer the load the measurement is taken, the smaller the loop impedance and displayed voltage. This allows you to easily check the terminal assignment by comparing the voltage and roughly determining the load. Don’t miss out! Combining polarity checks with additional information by measuring the voltage and displaying the signals is an effective way of detecting the most common wiring errors. It will shorten your testing time while increasing the safety of your installation. Wiring testing with CPOL3 FIND OUT MORE ABOUT THE CPOL3 HERE omicronenergy.com/cpol3 CT P2 S2 P1 S1 B A 4 3 2 1 X Test set Test switch Relay or meter Load 19
OUR CYBERSECURITY SYSTEM SHINES WITH DISTINCTION OMICRON receives security certificate from the BSI. 20
Magazine | Issue 1 2024 The German Federal Office for Information Security (BSI) has awarded our intrusion detection system StationGuard with the Fixed-Time Cybersecurity Certification (BSZ). We are the first intrusion detection system to receive this certificate. The BSZ certificate confirms the security performance of StationGuard and its compliance with the BSI’s high cyber security requirements. This milestone in intrusion detection confirms security performance of our system in compliance with all regulatory safety requirements. What does the BSI IT Security Certificate mean for our customers? Customers worldwide can rely on the highest quality and security of our solution. StationGuard fulfils the security functions required by the BSI, which have been confirmed by four test activities based on the planned procedure: › Testing of installation documentation › Conformance testing › Penetration testing › Evaluation of the implementation of cryptographic algorithms. We know that every network is unique, so we work closely with our customers to provide customized solutions and increase cybersecurity. Cybersecurity can only be achieved through highly effective vulnerability management and accurate risk assessments. Effective intrusion detection and management: StationGuard and GridOps set new standards Regardless of the BSZ certificate, we continue to optimize our solutions to meet the needs of the energy industry. For example, StationGuard’s add-on GridOps provides you with an optimal management interface for the StationGuard sensors in the grid, allowing you to collect and immediately analyze all the data provided. At a functional level, this means: › StationGuard The StationGuard IDS collects detailed data from each piece of equipment. The innovative allow-list system provides prompt and precise intrusion detection, reduces false alarms, and ensures the device is quickly ready for use. All alerts can be understood by OT and IT employees, facilitating smooth cooperation. › GridOps GridOps provides comprehensive asset inventory, an alarm dashboard, sensor management, centralized user management, and vulnerability management with extensive reporting. Customers only see the vulnerabilities relevant to them for successful vulnerability management and efficient responses. LISTEN TO THE PODCAST Interested in this topic? How exactly does the StationGuard solution support the work of IT and OT experts? Do you know why effective vulnerability management and a comprehensive risk assessment are crucial for cybersecurity? In our podcast episode, „Vulnerability Management in Substations and Power Plants“ (ENU), you can learn more about this topic as well as how StationGuard supports the work of IT and OT experts. Scan the QR-Code or visit: omicron.energy/episode71-en 21
TEIAS, an electrical transmission utility in Türkiye, relies on MONTESTO 200 as part of its holistic approach to assessing the insulation condition of power transformers in its repair workshop and the field. Introduction Power transformers are one of the power grid’s most important highvoltage (HV) assets. They are the key elements in generation, transmission, distribution networks, and industrial sites. With the advancing age of power transformers worldwide, it is vital to check their insulation condition by continuously assessing the health of various components to ensure reliability. A power transformer is exposed to many stress factors during its life cycle due to environment and load conditions, high electrical field stress, mechanical vibrations, and chemical contamination. A lack of a regular diagnostic testing and maintenance plan can result in eventual undetected insulation faults that can shorten the expected service life of a power transformer. Assessing insulation condition in power transformers A holistic approach is generally adopted for the overall check of insulation condition in power transformers based on Dissolved Gas Analysis (DGA), various electrical tests, monitoring, and visual inspections. DGA results from the insulating oil are used as a first alarm for any evidence of problems that can occur inside oilfilled power transformers. Abnormal levels of certain gasses can indicate potential problems, triggering additional investigations to identify and localize HOW TO VERIFY SUSPECTED INSULATION FAULTS IN POWER TRANSFORMERS 22
Magazine | Issue 1 2024 developing faults using electrical testing, monitoring, and a direct visual inspection inside the transformer. Advanced electrical testing and diagnostic tools, such as Dielectric Frequency Response (DFR) testing, Sweep Frequency Response Analysis (SFRA) testing, and Partial Discharge (PD) testing and monitoring, are now widely used to assess and diagnose the insulation condition of power transformers by detecting certain faults that conventional testing methods are unable to detect. In this article, we will focus on PD testing and monitoring. Partial discharge testing on power transformers According to the IEC 60270 standard, a PD is a localized dielectric breakdown of a small portion of a solid or liquid electrical insulation system under high-voltage stress. PD is a reliable indication and an accelerator of fault development in electrical asset insulation. This is why PD measurement and monitoring play an important role in assessing insulation condition to maintain the health and reliability of electrical equipment, such as power transformers. PD measurements on power transformers are initially performed at the factory as a quality control tool to assess transformer insulation condition according to specified acceptance criteria. During commissioning, PD measurements are performed to check the power transformers’ installation condition after transport. During the power transformer’s service life, PD measurements and monitoring are regularly performed for troubleshooting to detect and localize potential faults. Increasing hydrogen (H2) levels were indicated after performing a DGA analysis on a 154/31.5 kV (100 MVA) 3-phase power transformer. «After we opened the transformer for visual inspection, it became clear that our assumptions based on the PD test results were correct.» Mükremin Yanan, Chief Engineer, TEİAŞ Turkish Electricity Transmission Corp. CO 0 20 40 60 80 100 % H2 CH4 C2H6 C2H4 C2H2 PD T1 T2 20 40 60 80 80 60 40 20 20 40 60 80 T3 D2 D1 DT % CH % C H % C H C H C H C H CH H PD S D1 D2 T2 T3 T1 D1 Discharges of low energy D2 Discharges of high energy DT Mixed thermal and discharge faults PD Partial discharges S Stray gasses T1 Thermal faults (<300 °C / < 572 °F) T2 Thermal faults (300–700 °C / 572–1,292 °F) T3 Thermal faults (>700 °C / >1,292 °F) 23
Many utilities worldwide have established maintenance programs based on periodic PD testing and monitoring of their power transformer fleets since PD is a reliable indication of aging and developing faults in the insulation. Corrective actions can be taken before a developing fault eventually causes the asset to fail. PD testing, inspection, and repair of a 100 MVA transformer I am the Chief Engineer responsible for field test evaluation and test method development at TEIAS Turkish Electricity Transmission Corp. My team and I have developed a holistic approach to condition assessments and a solid maintenance plan for our grid assets, particularly power transformers. If potential faults are detected in the field, the transformers are taken out of service and sent to our central workshop facility in Ankara, Türkiye. Medium and large power transformers are tested and diagnosed in our workshop’s HV lab to determine if repairs and refurbishments are needed to return the transformers to reliable service. In one case, our test engineers investigated a 154/31.5 kV (100 MVA) 3-phase power transformer, which has been in service since 1996. A DGA analysis initially performed on the transformer in the field displayed a continuous increase of hydrogen (H2) and methane (CH4) gasses, which indicate potential PD activity and damage to the insulation in the transformer. Due to these increasing gas levels, we removed the transformer from the grid and sent it to our central workshop for further inspection and repair. Different 3PARD diagrams were obtained that indicated various potential PD sources. 3PARD diagrams showing the possibility of voids in the insulation material before and after the vacuum was applied. According to CIGRE 676, this PRPD pattern is very close to the one related to voids in glue. Traces of carbonization were found on various components. 24
Magazine | Issue 1 2024 In our workshop’s HV lab, our test engineers started by performing various electrical tests, including a DFR test, but no results were obtained to verify their suspicions of PD activity. PD testing revealed various PD sources As a next step, a series of PD tests were performed with OMICRON’s MONTESTO 200 temporary PD monitoring system using the induced voltage method. The PD tests were done over extended periods of time at different central frequencies and bandwidths to obtain the best signalto-noise ratio. The patterns obtained clearly indicated high PD activity from various PD sources. Thanks to the 3PARD diagram (3-Phase-Amplitude-Relation- Diagram), which is integrated into the MONTESTO 200 monitoring software capabilities, our test engineers could see many clusters, indicating various potential PD sources in the transformer, which could be separated for individual analysis. Analyzing different 3PARD clusters When applying the 3PARD filters on some clusters displayed around the three phases, symmetrical discharges around the zero crossing characterized a predominant PRPD (Phase-Related PD) pattern. The shape of the pattern indicated it was probably related to voids in the insulation material, possibly in the oil. Still, even after applying the vacuum to remove the oil in the transformer tank, the same discharges remained with the same PRPD diagram, which means that the voids might be on or inside the solid insulation. On the other hand, according to CIGRE 676, this PRPD diagram is very close to the one related to voids in glue. Besides, another PD source could be seen very clearly with the 3PARD filtering, and it was most probably due to carbonization on the pressboard barrier – mostly around phase W. Still, it could also be seen in the other phases. Filtering other clusters revealed yet another type of PD related to floating metallic particles around phases U and V. Visual inspection confirms PD testing results Based on the PD test results, our test engineers decided to open the transformer for a visual inspection to identify suspected damaged components. After the transformer was opened, it became clear that our assumptions based on the PD test results were correct, and the extent of the damage was immediately apparent. After removing the oil from the tank, many copper dust particles deposited in different places inside the transformer were visible. This copper dust was likely the floating metallic particles suspected when the oil circulated. Additionally, traces of carbonization were found in almost all the phases (HV coarse, HV fine, LV coarse) on the pressboards and wedges. In addition, our inspection team also found many traces of damaged and burned glue on the upper side of the coarse-tuning windings of phases B and C. The transformer was then repaired in our workshop. All the damaged parts were replaced with new components and materials. PD monitoring verifies the success of repairs Additional PD tests were performed in our workshop’s HV lab after the repairs were made, and no suspicious PD activity was detected. Once back in service, continuous on-site PD monitoring was performed for many months with the MONTESTO 200 device used in our repair workshop. No additional PD activity was recorded that indicated remaining or developing faults in the transformer. This was a verification to us that the repairs were successful. The transformer was back in reliable service. LEARN MORE ABOUT MONTESTO 200 omicronenergy.com/ montesto200 Traces found of damaged and burned glue. 25
Whether you wanted to buy a new car, build a house, or get hold of a game console to fill the hours during the lockdowns – since at least the beginning of 2021, we have all been feeling the effects of the chip shortage on the global economy. The crisis has also impacted the energy sector. Limited availability, astronomical prices, and unreliable delivery times meant we faced challenges on a scale we had never seen before. Meanwhile, our delivery times have long since returned to their pre-crisis levels. Below, we explain how we achieved this and what it means for future orders. Causes and consequences of the component shortage The causes of the component crisis were varied, and they still are. They can be partly attributed to the coronavirus pandemic and have also been influenced by other global and socio-political events, leading to a complex situation. › Lockdowns severely restricted production in many areas. › The significant increase in demand for home entertainment and office equipment resulted in a massive demand for semiconductor components. › Passenger transport came to a standstill during the international NO SHORTAGE OF SHORTAGES Impact of the component crisis on the energy sector. 26
Magazine | Issue 1 2024 lockdowns, further restricting freight capacity and causing shipping costs to rise. › The conflict between Russia and Ukraine intensified supply chain challenges in specific sectors by restricting deliveries of metals, food, chemicals, and other raw materials. › The increasing popularity of electric cars is also affecting the availability of components, as these vehicles require considerably more electronic components than those with combustion engines. The consequences were uncertain and unreliable delivery times and a price increase of over 400%. We were forced to obtain components via new channels, which – in addition to astronomical prices – also introduced a quality risk, resulting in additional quality assurance tests having to be performed for every delivery. A sustainable approach to the shortage It was clear to us from the beginning that we had to meet this challenge with a long-term approach that would also deliver quick solutions, fulfill our customers’ requirements, and guarantee consistent quality. To meet these high demands, we established an interdisciplinary Shortfall Panel. The panel aimed to monitor the situation, make decisions about specific critical orders and tenders, enable additional delivery time optimization, and ensure prompt and seamless communication with our customers and sales partners. Goals: reduce delivery times and ensure quality The Shortfall Panel’s objective was clear: keeping delivery times as short «It was clear that we needed quick yet reliable solutions, and they would only be possible with a high level of investment.» Johannes Malin, Shortfall-Panel Lead, OMICRON 27
as possible without compromising quality. Several measures were introduced for this purpose: Boosting stock The first and most obvious step was to stock up on all components and spare parts. We had a considerable advantage over many other companies in this respect, as we have longstanding partnerships with our electronic component distributors and often work directly with manufacturers. In addition, we procure a significant amount of our mechanical components and accessories from regional manufacturers, which to some extent limited the effect of global bottlenecks and transport problems. We bought unavailable components from our distributors if they had delivery times that were too long for us in other buying markets, sometimes at much higher prices. These components underwent intensive quality testing before being used in series production, helping us remain in a position to supply our products. At the same time, we invested in 21,000 m2 (226,042.12 ft²) of additional warehousing space to create more storage capacity. Order-specific needs assessment However, despite increasing stock levels, even we could not avoid all the bottlenecks, which occasionally required us to modify delivery times and assess and prioritize orders. The Shortfall Panel developed a process that enabled us to work on special orders with a higher priority, such as emergencies following natural disasters or for system-relevant applications. Seamless, transparent communication Communication with our customers and sales partners regarding delivery times was just as crucial. Remaining in close contact with them enabled us to understand and respond to their individual needs and manage their expectations. This made it possible to provide realistic delivery estimates and keep our promises. Long-term supply security In addition to drastically shortening delivery times, we also wanted to minimize potential long-term delay issues. To this end, we analyzed and optimized production processes. A dedicated team was assigned the task of looking for alternatives for components that were difficult to get hold of and proactively reworking our products, making it possible for us to use different components while achieving the same level of quality and functionality. More standard components found their way into our products, which should ensure availability even in the event of challenging market situations. Successfully normalizing deliverytimes Thanks to the joint effort of all the teams involved and significant investments in both time and money, delivery times have been steadily reduced, and over 95% of our products are now delivered within the pre-crisis time frame of four weeks or less. 28
Magazine | Issue 1 2024 WHAT’S NEW IN TEST UNIVERSE 4.40? Greater scope for your tests. Test Universe is the perfect tool for reliable and efficient parameter-based tests of protection relays. Our continuous product development has added new features in the latest version. For example, you now receive practical recommended actions in the event of connection problems, and it is easier to identify test sets and establish a connection. What’s more, it is now possible to connect to your favorite test set, even if it is offline or not within the network, opening up new possibilities, such as being able to prepare test plans for the team or working on several projects in parallel. There are also significant improvements in terms of configuring your hardware. When switching between different test set types, you can transfer as many reusable parameters and settings as possible. This is a great time-saver as you no longer have to re-enter parameters and settings repeatedly. Further improvements make the tool even more intuitive to use. Commissioning new protection relays without a Grandmaster Clock can be problematic, which is why you can now simulate a Grandmaster Clock with your CMC or even use an inaccurate Grandmaster Clock for time synchronization. You can use this feature to commission IEDs with Sampled Values even if the intended Grandmaster Clock still needs to be installed. Do you have to test residual voltages and currents regularly? Version 4.40 now offers the functionality you require in all relevant test modules so you can efficiently work with these variables using automated test procedures. With these comprehensive improvements, the new version sets new standards in terms of user-friendliness, flexibility, and efficiency for parameter-based testing of protection relays. You can find more information about Test Universe 4.40 here and download the new version for free. omicronenergy.com/testuniverse 29
Our journey began in the United States with Charles Sweetser in Maine. Charles explained why dead tank circuit breakers are commonly used in HV levels and how they are usually tested. We also discussed the importance of motion tests and their difficulties with him. Additional challenges in North America include the influences of Current Transformers that are typically built-in and how to overcome their effects on measurement results. We also emphasized the importance of performing insulation tests with dead tank circuit breakers. Our expedition took us across the Atlantic to Northern Germany, where we talked to Bastian Wölke from Westnetz GmbH. Dead tank circuit breakers are rarely seen; we discussed live tank circuit breakers, focusing on maintaining their vast fleet of MV circuit breakers. With 25 years of experience, Bastian has far-reaching insight into the most efficient testing procedures and trends from older circuit breakers as well as newer alternatives. We also had an in-depth discussion about the future of circuit breakers, how they might be tested, and the challenges of modern technologies. After getting a European perspective, we crossed the globe to arrive in Australia, where we gained more insights from Florian Predl and Tibor Congo from Melbourne. Interestingly, there isn’t a preferred type of circuit breaker in their area; dead tank and live tank circuit breakers are both commonly used, depending on the physical condition of the substation and the operators’ personal preferences. We learned about a specific practice that allows dynamic resistance measurements to be performed on dead tank circuit breakers, and we looked into future trends like online testing and monitoring. CIRCUIT BREAKER TESTING AROUND THE WORLD How are circuit breakers being tested on different continents? In our podcast Energy Talks we have published a circuit breaker testing series in which experts from different regions discuss what is essential to their daily work. USA Germany Australia 30
RkJQdWJsaXNoZXIy NTkxNzY=