Enterprise-level asset management systems do not adequately present—let alone capture—critical details about relays and other P&C components. Organizations risk heavy capital and revenue losses, non-compliance penalties, and injury or loss of life if specifics about P&C systems are obscured and information becomes misinterpreted because of limitations enterprise asset management systems have concerning P&C data.

A single solution for storing, managing, and analyzing P&C data is needed, yet organizations operate with a mix of commercial and home-grown software. Connecting protection engineering and test data to enterprise asset management systems is a struggle because diverse applications and tools used by P&C personnel emit data in dissimilar formats that were never intended for system-wide management in the first place.

Over time, P&C “systems-of-systems” impact worker efficiency by introducing additional steps and requirements whenever new technologies or initiatives are adopted. When key personnel move on, managers might face situations where employees use workarounds to navigate cumbersome tasks and process gaps.

P&C workers today have many more responsibilities than ever. In addition to growing requisite skills and knowledge to do their jobs, they are impacted by numerous compliance-mandated priorities. Office-to-field operations between engineering and testing teams must be cyber secure while specific details about their work must be tracked and documented.

Highly trained P&C professionals diverted to compliance tasks add expense onto protection system development, commissioning, and maintenance. P&C support staff step in to ease the administrative burden, but they become overloaded tracing data points generated out of complicated—and usually manual—workflow and reporting processes. IT teams become tethered to supporting P&C software—new and old—while consulting department administrators in complex matters surrounding compliance readiness regardless of technology and workforce dynamics.

Although similar situations could also exist in other areas of utility and industrial organizations, protection system data is mission-critical to the company’s most expensive and highest-profile assets. Timely insight into the condition of relays and the other components of the protection system is essential to system operators, work planners and to the safety of employees who repair system equipment and maintain transformers, breakers, and other apparatus.

Doble PowerBase provides a management platform tailored to both P&C data and protection system work. It consolidates data from engineering, field and administrative areas while offering data exchanges with external systems. All stakeholders, including those from asset management, compliance, and IT gain clearer views of protection system information and have powerful reporting tools at their disposal.

Additional Information:

• Product Information – Doble PowerBase
• Further Reading: Theory Meets Testing: Life of a Transformer Seminar’s Transformer Relay Protection Program
• Learn More: Protection Training and Education Opportunities

The post Shedding Light on Protection System Maintenance Data appeared first on Doble Engineering Company.

Microgrids are gaining ground with each passing year in different parts of the world. In the United States, one of the main drivers that advanced the concept of microgrid was Hurricane Sandy. This hurricane, which hit the northeast part of the US in 2012, caused havoc with the transmission and distribution system. The advantages presented by smaller, self-sustaining grids started to look very attractive and there was a much greater interest in such small grids.

However, microgrid is not a new concept. If we look in the rear view mirror, we find that the original concept of a microgrid dates back to the 1800s. In 1882, Thomas Edison had built the first commercial direct current (DC) power plant. This plant, which was named the Manhattan Pearl Street station, was part of a small grid serving 82 customers with a distribution area of a few blocks. This plant also served as a combined heat and power source supplying both to customers. In addition, batteries at this plant served as power storage. This distribution was a standalone system with no external grid present. As years went by, alternating current (AC) started winning the race with DC (direct current) and the electrical grid as we know it today started taking shape. The energy sector started expanding and finally evolved into large electric utilities that generated, transmitted and distributed electric power. The result of this was a massive mesh of interconnected grids spanning the entire US. A similar evolution took place in Europe followed by Asia and other parts of the world.

The next big step in the electrical energy sector in the US occurred in 1978. In that year, a law called The Public Utility Regulatory Policies Act was enacted (PURPA). This act had its origins in the energy crisis of 1970s. The intent of PURPA was to encourage cogeneration and renewable sources that would promote competition and conservation. This resulted in several industrial plants installing steam/gas turbine generation. The local generators provided both electric power and steam that the plant could use. The generators operated in parallel with the grid. The plant could sell excess power to the host utility. In case of loss of the utility grid, the generators supplied the local plant load. Some plants supplied the local load and only upon loss of the local generator, would the host utility start to provide power to the plant in a seamless fashion. During under voltage conditions in the grid, the local generator provided reactive power to stabilize the grid voltage.

Later on, several independent power producers started building power plants to sell power to the electric utilities. PURPA had a clause that required the host utility to purchase power from these entities at reasonable prices. In several instances, host utilities offered attractive rates if the plant owners agreed to support grid stabilization by supplying MW and MVAR.

Differences and similarities between old cogeneration concepts and new microgrids

Local generation at the plant along with the plant distribution was in fact a microgrid. The generator supplied the local load and the plant had the option of switching over the load to the grid. This sounds very familiar with what we are seeing today with microgrids.
The in-house generation was also installed at parks, prison facilities, large telecommunication centers, etc. and the same applies to microgrids of today.

Microgrids consist of a diverse mix of distributed generation such as wind turbines, solar panels, fuel cells, and bio-mass fired. All of these sources if supported by a battery storage will enable power to be available around the clock. Microgrids have two things going for it ̶ the declining cost of Lithium-ion batteries and the increasing affordability of renewable energy.

There are some differences between what we see today in microgrids and the old cogeneration facilities:

1. The generation at industrial plants, commercial facilities, parks, and jails consists of one or several generators located at one location. This is not the case with microgrids; generation is dispersed.
2. Conventional generators did not create harmonics while the microgrids do generate harmonics. The issue of harmonics is resolved by applying appropriate filtering.
3. The short circuit current provided by the generators at cogeneration facilities is adequate to accommodate effective relaying both at medium and low voltage buses. Renewable sources do not provide adequate short circuit currents.
4. Microgrids do not possess adequate inertia to support system stability.
5. Most of the generation in the microgrids are renewable sources but can also contain a conventional source.
6. Microgrids with renewable sources are environment friendly and provide clean energy.
7. In the case of microgrids the load is not necessarily one concentrated plant or facility. The load may consist of a mix of loads such as homes, schools and a hospital spread over a specific area.

Hence, we can see that the microgrids of today have several similarities with some exceptions. The advances made in the area of automation, communication and digitalization makes the microgrid quite different from the old cogeneration facilities.

Issues with new microgrids and possible solutions

There is no doubt that microgrids provide an array of benefits. However, microgrids do present some issues and challenges, which the industry is addressing.

The issues and possible solutions are:

• In situations where the microgrid operates in an isolated mode with no synchronous generator present starting of large motors will be difficult.
• Coordination between protective devices based on simple overcurrent relays is difficult due to inadequate short circuit current present both in terms of magnitude and time duration. This will be true for coordination between 480/277V as well.
• Differential relaying for both transformers and the lines, at several locations, will be required to provide a coordinated system with the required level of selectivity.
• Protective schemes will require adaptive relaying coupled with communication link between various protective devices.
• Application of protective devices that are compliant with IEC standard 61850 will be helpful. This means implementing protection based on GOOSE messaging which provides a good option.
• The 480V devices that consist of molded case circuit breakers and breakers with solid- state trip units. There is no formal coverage of 480V devices in IEC 61850. However, manufacturers have devised means of incorporating these devices into IEC 61850 based schemes.
• One of the drivers that pushed microgrids is the fact that during storms when the main grid is lost, the microgrids can keep supplying power to the assigned loads. However, this may not be true if the microgrid coverage area includes overhead distribution lines. Underground distribution will help alleviate this issue.
• There is a lot of research going on in the area of enhancing the converters applied at renewable generation. The issue of inertia, and lack of adequate short circuit both from magnitude and time duration perspective is being addressed.

More Information:

• Blog – Wind Power Generation: The Journey to a Cleaner Future
• Services – Maximize your assets and minimize outages
• Training – Fundamentals of Renewables

The post Microgrids – Old Concept on Steroids appeared first on Doble Engineering Company.

“I was genuinely humbled to be considered for this role in the first place and feel honored to have been selected,” he says.

“It’s a time of tremendous change in our industry and the need for new solutions to meet the challenges ahead has never been greater: materials underpin many of these future innovations. I’m looking forward to working with all the representatives from around the world who make up the Study Committee and the wider CIGRE community,” Simon added.

About CIGRE

Established in 1921 in Paris, France, CIGRE is an apolitical, not for profit global community committed to the collaborative development and sharing of power system expertise.

Its scope is organized in 16 domains of work, each led by a dedicated Study Committee. Domains are broadly grouped by four key global power system areas—equipment, technologies, systems and cross-cutting groups (new materials and IT).

The 16 study committees have approximately 250 working groups active at any one time. These working groups in turn produce comprehensive technical publications, referred to as ‘Technical Brochures’ which cover the full spectrum of the power system and often serve as feeders for new standards and as best practice user guides for utilities.

Every two years CIGRE members congregate in Paris for their signature five-day global conference—The Paris Session—where hundreds of technical papers are collaboratively debated.

The D1 Study Committee

Materials and Emerging Test Techniques, also known as the D1 Study Committee, covers new and existing materials for electrotechnology, diagnostic techniques and related knowledge rules, as well as emerging test techniques which are expected to impact power systems.

As an overarching committee, D1 collaborates closely with and supports other committees across the CIGRE domains, including cables, circuit breakers and transformers. The voluminous output of its over 20 working groups supports the ongoing development of international standards. Key areas of focus in recent years have been new dielectric liquids (natural and synthetic esters), insulation ageing under HVDC conditions and the emergence of alternative gases to SF6. Other topics have included corrosion, partial discharge measurements, DGA monitoring systems and superconductivity.

Twenty-Five Years of Dedicated Service

Simon has been active in CIGRE for the past 25 years and in 2020 he received the Distinguished Member Award acknowledging his long-standing collaboration and service.

For the past seven years he’s been very engaged with the D1 study committee, most recently serving as a Convenor of the D1 Advisory Group on Solids (D1-03), which determines the terms of reference for new working groups.

He’s also served as a Special Rapporteur for the Paris Session—the main CIGRE conference held every two years. Special rapporteurs play a key role ensuring a successful conference by reviewing the submitted papers ahead of the conference, preparing a report and posing the questions to be debated during the session meeting.

The Benefits of Participation

It goes without saying that Simon is a big advocate for CIGRE. He recommends that other power system professionals become active with the organization.

“If you get involved in a working group,” he says, “it’s great for your professional development because you’ll be working with upward of 30 of your peers who obviously have an interest in the same topic. It’s an opportunity to develop a huge professional network and you’ll be driving international standards to where they need to be.”

Simon adds, “CIGRE is a truly global organization—it’s a melting pot for bringing everyone together. You meet people from everywhere and you get that global perspective of what’s going on.”

“I believe people should get involved in CIGRE. If you’re passionate about the industry—and people talk about ‘giving back’—it’s a good way of doing that,” he says.

Additional Information

• CIGRE Website
• Materials and Emerging Test Techniques (D1)

The post Simon Sutton Confirmed as the Next CIGRE D1 Study Committee Chairman appeared first on Doble Engineering Company.

Power and utility companies play a starring role in safeguarding the nation’s infrastructure. As organizations double down on compliance and technology, there are several things to consider amidst a rapidly evolving cybersecurity landscape.

Confidently and compliantly secure your assets

Maintaining compliance with NERC-CIP standards is just the first, yet critical, step in boosting cybersecurity defenses. These mandates were put forth to institute a bare minimum for security. Keeping up with effective Transient Cyber Asset (TCA) (NERC CIP TCA), vulnerability and patch management and assessments, (NERC CIP-007/NERC CIP-010) and enterprise patch management (NIST SP 800-40 Rev. 3) best practices is foundational to ongoing cyber protection.

In addition to choosing technology that makes it easier to adhere to these standards with continuous monitoring, quick patch management, and other capabilities, it’s important the tools you’re using also maintain compliance with these standards.

Make sure any software you’re using to manage your assets and their security exceeds NERC CIP-007-6 R2.2 for timely patch evaluations to ensure compatibility. Also ensure that the software has undergone an authenticity and integrity verification process according to NERC CIP 010-3 R1.6 so you know the system is from a legitimate source and hasn’t been modified.

Invest in transient cyber asset security and patch management

Remote field devices can present major security risks. Transient cyber assets (TCAs) such as tablets, asset testing laptops, and protective relays are often disconnected from the main network, making them a prime channel for spreading malware. Given TCAs contact critical assets regularly, they’re a top security threat if not secured properly.

Speed is of the essence when it comes to cybersecurity. However, securing your assets shouldn’t hold productivity back. Look for systems that you can tailor to secure the work processes that need defenses the most and streamline procedures from the field to the office. Tapping patch management software that easily shows the patch updates available to TCAs, enables you to quickly select the updates you want, and automatically downloads those installers to TCAs to be installed during remote updates is key for success. Patch management systems should also monitor, send alerts, and report on security risks, keeping you in a constant state of vigilance.

Stay prepared and proactive

Cyber threats are fast moving and unpredictable. Utilities need to be armed and ready with the right tools and processes. While advanced technology for threat identification and management is currently strongly encouraged by the Biden administration, it could soon become a requirement.

About the authors

Bryan Gwyn is the Senior Director of Solutions at Doble Engineering. He has over 10 years of executive experience in the transmission and distribution business and a demonstrated history of working in the utilities industry.

Sagar Singam is a Cyber Security Engineer III at Doble. He is passionate about secure coding, cyber security and products. He graduated from the A. G. Patil Institute of Technology and earned his master’s in Information Assurance and Cybersecurity from Regis University.

Dan Coombs is the DUCe Support Manager at Doble. He has over 13 years of experience in system engineering and holds a bachelor’s degree in Information Technology from Daniel Webster College.

More Information:

• Blogs:
  • A Refresh on Cybersecurity: How Utilities Can Act Now
  • 100 Years of Doble: Securing the Power Grid When It Matters Most
• Products:
  • Security & Compliance
  • Transient Cyber Asset Program
  • PatchAssure

The post Cyber Threats on the Rise: Invest Now to Boost Power Grid Defenses appeared first on Doble Engineering Company.

The importance of relay testing cannot be overstated given the consequences of protection system failures in today’s power delivery environment. The role relays play in protecting power transformers, generators, motors and other critical electrical components hasn’t changed, but protective functions are now just a portion of what must be verified during tests. Modern relays can have thousands of setpoints and can be configured for increasingly sophisticated applications. Personnel must adapt test systems and practices to accommodate analog, digital, and hybrid analog-digital protection schemes at their companies in an era when there has never been more scrutiny of their work.

The expenses and complexities of modernizing protection systems with new, advanced relays are exacerbated by test equipment limitations. Proving relay functions requires multiple intricate analog and digital simulations. Test systems must comply with standards and protocols for communication and timing used in substation networks. When limited by test gear, companies might either forego using the added functions of modern relays or move forward by leveraging new relay capabilities with different test gear for specific, one-off purposes.

Having different test instruments for different protection applications causes inconsistencies that can eventually undermine test and maintenance program effectiveness. Companies can be pressed into a false choice between standardization or flexibility and become stuck in the status quo where reaching their asset management objectives remains elusive in the face of compounding equipment and software variables.

Doble F8000-series Power System Simulators let companies move forward with evolving protection technologies without disrupting existing operations. By providing feature sets that are modular, Doble F8000-series instruments can be offered in numerous configurations. Companies can select F8 instruments that have the configurations they need for their unique testing requirements. As a platform, the F8000 line of four- and seven-module instruments provide a consistent user experience across all configurations that are offered.

The key component of each F8000-series Power System Simulator is the embedded Command Module which opens a world of possibilities for secondary injection testing across the numerous instrument configurations of current, voltage and logic I/O modules on the F8000 platform. By design, the Command Module enables comprehensive analog, digital, and hybrid analog-digital test cases driven by Doble Protection Suite and Doble RTS software.

Compliant with substation networks

Relays must be precisely time-aligned to other devices in substation networks. Testing relays in system simulations requires test equipment that supports the timing standards used in substation network communications and provides exact synchronization with signals in play between devices.
The Command Module hosts advanced electronic components that provide the needed connectivity and performance for relay system test operations from F8000 Power System Simulators.

The GPS port works with satellite receiver antennas, like the Doble F8895, to synchronize F8000 instruments to substation network time-of-day references. A port is provided for synchronizing F8000 operations to the timing of communication signals according to the IRIG-B protocol which is commonly used in substation control systems. Synchronization at pulse-per-second (PPS) timing is supported by default and there is the F8053 firmware for complying with 100 nanosecond Precision Time Protocol (PTP) time resolution which is used by network Grandmaster clocks. The two copper and fiber selectable SFP ports and the three RJ-45 ports offer Ethernet connectivity for interfacing directly with conventional microprocessor-based relays, digital Intelligent Electronic Devices (IEDs), network switches or other computerized protection and control devices in substation networks.

Supports testing digitally

Getting online with the IEC 61850 standard can be easier said than done. Applying IEC 61850 in new substations is far less complicated than upgrading substations that are already in service. Utility and industrial companies can struggle when confronting new test requirements presented by digital protection systems when their existing testing program is designed around conventional relay testing.

The Command Module allows companies to have a single test instrument that offers the flexibility to test digitally with virtual simulations on IEDs (using Protection Suite), or to test with analog simulations on conventional relays (using Protection Suite or RTS). The flexibility to support both virtual and conventional simulations in the same test sequence – hybrid testing – is also supported.

The powerful virtual test and analytical operations in Protection Suite work through the Command Module which can isolate control, sampled values (via F8870 module), GOOSE (via F8860 module) and PTP networks, and separate or overlay discrete signals according to parameters configured in the software.

The feature sets provided with F8000 test instruments through the Command Module give companies the best of both worlds. They can maintain existing relays and implement the latest digital protection technologies from one test set that provides all the features and capabilities that are necessary either way.

Standardization that doesn’t limit you

F8000-series Power System Simulators eliminate the need to have add-on test devices to accommodate different types of relay tests thanks to the network-compliant components built into the Command Module. Utility and industrial companies can equip their relay test personnel with F8000 instruments of any configuration and keep a consistent user experience across teams who may specialize in different types of protection testing.

The modular approach Doble has taken with the platform of F8000-series instruments offers flexibility upfront with configurations that are suitable for different purposes, and in day-to-day test situations whether analog and/or digital simulations are necessary. For personnel who test relays, having a single piece of test equipment with the volt-amps, required connectivity, and facilities for virtual testing can be a huge advantage day-in-and-day-out.

Modern protection testing shouldn’t be bound by test equipment limits. See the difference F8000-series Power System Simulators can make in your protection testing program.

Additional Information:

• Video: Doble F8000 – Command Module
• News: Doble Engineering Company Launches F8000 Power System Simulators
• Further reading:
  • Meet the Next Generation Protection Testing Platform: Are You Ready to Go Further?
  • The Protection Testing Opportunity: Evolving into the Digital Age and Beyond

The post F8000 Command Module: The Gateway to Next Gen Protection Testing appeared first on Doble Engineering Company.

Doble’s INSIDEVIEW® software removes these complications from insulating liquid laboratory analyses and diagnostics, and provides teams with unparalleled simplicity, efficiency and expertise. Doble also provides premier implementation and support services so that INSIDEVIEW can be configured to align with a company’s unique business processes.

1. Offers Intuitive User Interface and Simplified, Configurable Enterprise Deployment

INSIDEVIEW centralizes fleet oil management for easy accessibility and streamlines workflow between laboratories, experts, field personnel and asset managers with a modern, easy-to-navigate user interface. Teams can evaluate over 130 laboratory tests and access advanced analytics based on latest IEEE, ASTM, IEC and Doble recommended limits as well as customer defined criteria.

Customizable dashboards provide a comprehensive view of the health of their entire fleet and individual apparatus. Alerts on the availability of new test or lab sample data, assets that change condition status, or monitored assets that have not received recent data keep teams up to date and focused on the most important tasks.

INSIDEVIEW offers user-defined roles based on organizational job responsibility for optimal accessibility and streamlined workflow. Teams can integrate off-line laboratory test data, on-line DGA monitor data and portable DGA analyzer data and group assets into categories such as by location or substation to simplify the management process. Advanced features such as the ability to create customized health index calculations and a resampling management module that can determine next sample timing allow for more strategic and efficient asset management.

2. Integrates Seamlessly with Existing Systems

INSIDEVIEW’s configurability to integrate data from different sources and adapt to existing business practices enables teams to meet their unique business goals. Using Doble-provided templates, INSIDEVIEW offers data conversion from CSV /Excel formats and offers an INSIDEVIEW test/QA environment option alongside a live production environment for enhanced versatility.

Doble offers data integration options from customer laboratory information management systems (LIMS) to INSIDEVIEW as well as from INSIDEVIEW to CMMS solutions such as Maximo®, Cascade, etc. By integrating data sources and cooperating with various 3rd-party business systems, INSIDEVIEW’s technology helps ensure maximum benefit and optimal performance.

Additionally, INSIDEVIEW provides a native integration with Calisto® DGA condition monitors as well as a 3rd-party DGA monitor integration option through a data historian.

3. Integrates Natively with Doble Laboratories

For customers working with Doble laboratories, INSIDEVIEW automatically uploads your information and digitizes current manual processes. INSIDEVIEW provides detailed DGA, oil quality and paper degradation analysis as well as Duval triangles/pentagons, Rogers Ratio and more. The product also incorporates NEIoil and NEIpaper calculated values and gas generation rates that allows users to ascertain fault severity.

4. Complies with the Latest Cybersecurity Standards

As cyberattacks become more sophisticated and targeted toward critical infrastructure, safeguarding power grid technology has never been more important. Ensuring compliance with the latest protective measures is a critical and foundational step for effective cybersecurity risk mitigation and management.

INSIDEVIEW comes either as an on-premise or cloud-based solution leveraging state-of-the-art security delivered in Microsoft Azure Cloud data centers globally. Doble also performs routine penetration testing to mitigate cyber-security vulnerabilities.

5. Leverages Doble’s Design and Field-testing Experience

INSIDEVIEW users gain the expertise of laboratory experts, design engineers and performance specialists backed by a company with over a century of industry experience. Users can create transformer diagnostics specific to family design based on Doble’s latest design and field-testing research.

Users can further contact Doble design and performance specialists for consulting in areas such as alternative insulating liquids, stray gassing, corrosive sulfur and paper/cellulose degradation.

Deep Insights for Quick, Effective Decisions

Managing asset health should not be complicated. INSIDEVIEW enables users to save time by eliminating the technical and integrative complexities of asset management while achieving a thorough and comprehensive view of their fleet. With built-in advanced analytics, utility teams can confidently and quickly make informed decisions to proactively manage asset risks.

Authors:

Brian Snyder received his M.B.A from the University of North Carolina at Chapel Hill. He is Solutions Director of Professional Services at Doble Engineering Company, where he is responsible for service strategy of consulting services, laboratory services, condition monitoring service programs and training courses. He has extensive global experience working with power generation, transmission and distribution and industrial clients to develop client-specific service strategies.

David Koehler is the Business Development Manager-Professional Services for Doble Engineering Company. He has 23 years of experience in the testing of insulating liquids and management of analytical laboratories. He has provided numerous technical presentations and published technical articles within the power industry. David is Vice President-Elect for IEEE Member and Geographic Activities (MGA) and a member of IEEE’s Honor Society: HKN. David served on the IEEE Board of Directors from 2019-2020 and again will serve on the IEEE Board of Directors in 2022. David is a member of the ASTM D-27 Technical Committee on Electrical Insulating Liquids and Gases.

Francis Béliveau received his Bachelor’s Degree in computer science from the Sherbrooke University. He is the software architect of INSIDEVIEW and Doble Security Portal at Morgan Schaffer and Doble Engineering Company for the last 10 years. He has a vast background developing products for DGA, laboratory data, NERC-CIP and cybersecurity. He has extensive experience of integrating Doble solutions with our electrical customers.

Additional Information:

• Product: INSIDEVIEW®
• Blog:
  • Confident Asset Health Decisions Start with Real-Time, Quality Data
  • Three Serious Questions to Ask Now About Condition Monitoring
  • Purchasing a New DGA Monitor? Read the Fine Print

The post Five Ways INSIDEVIEW Brings Clarity from Complexity in Insulating Liquid Asset Management appeared first on Doble Engineering Company.

Although simple visual inspection of the transformer tank (to look for corrosion or leaks) or IR surveys (to identify overheating pumps) yields important condition information, not all issues will be visible from the outside. Fortunately, incipient faults occurring within the transformer can be identified and diagnosed by examining the chemical, physical and electrical properties of the liquid dielectric within it. This is usually done in an external laboratory; however, some larger utilities or industrial entities may undertake in-house testing.

In this three-part series of blogs, we will:

1. Look at the importance of sending high-quality oil samples to the laboratory to be tested.
2. Consider the types of problems that can be identified by Dissolved Gas-in-oil Analysis (DGA) and what next steps may be taken.
3. Consider other oil tests that are conducted, and the important information that can be revealed.

Importance of a High-Quality Sample

An oil sample can reveal a wide variety of information about the condition of your asset; this includes evidence of overheating, partial discharge and arcing, paper degradation, water ingress, oxidation, presence of chemical and physical contaminants, and more. Consequently, oil testing is a key method for assessing a transformer’s condition and identifying incipient faults before they become critical. A single measurement is valuable, but trending changes in the data over time enhances the diagnosis revealing the severity of the situation and enables asset managers to plan appropriate actions. This could involve offline electrical tests to determine the underlying cause, fitting online monitoring devices to monitor the condition of the asset more effectively, or scheduling a repair or replacement.

Ensuring good results for your assessment starts with delivering a good oil sample to the lab. Even perfectly performed lab tests are rendered meaningless if they are based on a poor sample. Failing to take the sample correctly will inevitably lead to bad results, and the additional cost of having to retake the sample and perform the analysis yet again. A good sample needs to be truly representative of the bulk liquid circulating within your electrical equipment. Getting to this representative oil requires several liters of oil to be flushed through the sampling pipework and into an appropriate waste oil container prior to collecting the sample proper. In the process of waiting for the flushing to complete, this oil can be used to rinse the sample container and caps, to ensure they are free from physical contamination.

When taking a sample, it is beneficial that your container is large enough to hold the amount oil needed with some extra just in case the lab needs to repeat a test to verify unusual results; this typically means about 1 liter. There are many suitable containers for taking an oil sample and each has its own benefits and pitfalls. Generally, glass/aluminum bottles or tin cans are the preferred options. The container should properly seal the sample, preventing ingress and egress of any liquids and gasses. As oil degrades in sunlight leading to the synthesis of hydrogen, the containers, sleeves and/or packaging should be light proof to protect the sample from sunlight.

Plastic bottles should be avoided, since water molecules are able to diffuse through the container walls, thus increasing the water content of the sample; studies have revealed that 10’s of ppm water can enter the sample during transportation and storage before testing. Conversely, small molecules like hydrogen can diffuse out of the oil through the plastic container walls decreasing the concentration ultimately measured in the sample.

Lastly, it’s important to pack the samples well to avoid damage during transportation to the oil testing laboratory. Make sure the bottoms of the bottles are protected as well.

Insulating oil is the lifeblood of transformers. Periodic oil testing based on condition and criticality of the asset, enables users of oil-filled high voltage equipment to detect incipient faults, monitor their progression and plan appropriate action before minor issues become bigger issues, or at worst failures.

In the next blog will we look at the information provided from Dissolved Gas-in-oil Analysis testing.

Authors:

Simon Sutton has over 25 years’ experience in the electricity transmission and distribution industry predominantly in the cables sector. He has worked in the cable materials supply industry, as the cables policy manager for a transmission utility and in the research sector. His interests also include condition monitoring, diagnostic testing, forensics and asset management. Simon now works as Director of Services for Altanova, a Doble company, and is based in the UK. His responsibilities include business strategy, external relationships and coordination of technical activities around the world. Simon holds a degree and PhD in Physics both from the University of Reading. He is active in International professional bodies representing UK on the CIGRE Study Committee for Materials and Emerging Test Techniques, Convenor of the CIGRE Strategic Advisory Group on Solids and is a member of the editorial board of the IEEE Electrical Insulation Magazine. He is a Visiting Senior Research Fellow at the University of Southampton.

Lance R. Lewand is the Technical Director for the Doble Insulating Materials Laboratory. The Insulating Materials Laboratory is responsible for routine and investigative analyses of liquid and solid dielectrics for electric apparatus. Since joining Doble in 1992, Mr. Lewand has published over 75 technical papers pertaining to testing and sampling of electrical insulating materials and laboratory diagnostics. Mr. Lewand received his Bachelor of Science degree from St. Mary's College of Maryland. He is actively involved in professional organizations including the American Chemical Society, a representative of the U.S. National Committee for TC10 of the International Electrotechnical Commission (IEC) and ISO TC28, ASTM D-27 since 1989, Chair of ASTM Committee D-27, sub-committee chair 06 on Chemical Tests, secretary of the Doble Committee on Insulating Materials, and a recipient of the ASTM Award of Merit for Committee D-27.

Andy Davies has been working for Doble for 6+ years. His work commenced with 2.5 years in the Middle East; providing asset health indexing and maintenance guidance for over 2400 transformers for a middle eastern transmission company. Since then, he has been involved with support and training for online asset management tools like dobleARMS and INSIDEVIEW, hardware support for portable and field oil testing equipment like Calisto, Myrkos and Domino and provides transformer consultation for customers located across EMEA. Prior to Doble, he worked with an oil services company; that provided oil reclamation and mobile oil solutions that included technical consultation for all generators, HV contractors, transmission and distribution utilities across the UK and Ireland. He has led research into DBDS and Acidity in transformers and their mitigation strategies and has a sound understanding of oil chemistry.

Additional Information:

• Laboratory Services
• Laboratory Diagnostics Training

The post Assessing Transformer Condition – Part 1: Common Tests & Best Practices to Implement Now appeared first on Doble Engineering Company.

Introduced in 2017, the extraction of exciting current components opens the door for a further enhancement of electromagnetic circuits’ diagnostics. Traditionally, analysis of single-phase exciting current and loss data relies on total current, loss and power factor. For some units, the prominence of the capacitive current component masks the behavior of the inductive component, yielding to uncertainties of the diagnostic criteria. The method allows the separation of the essential constituents of the total measured current and the report of all three, namely, I_R, I_L and I_C components.

The total measured current (I_meas) during an exciting current and loss test is comprised of three current components, identified in Fig. 1 as I_R, I_L and I_C. In most units with lagging I_meas, the patterns can be predicted by knowing the core type and inspecting the electrical diagram on the nameplate. In some cases, however, the presence of capacitive loading distorts the expected current patterns, making the diagnostic conclusions less certain. The method that extracts I_L and I_C, allows the assessment of electromagnetic circuit free from the effects of capacitive loading.

Figure 1. Equivalent circuit of a transformer under no-load conditions

Origin of Current Components

Understanding the phenomena that dictates the behavior of the current components is essential for the data analysis. A brief synopsis is given below.

Inductive Current – I_L

The inductive current is a function of total inductive loading present during the single-phase exciting current and loss test. The objectives of I_L are twofold: 1) to maintain the core magnetized; hence, it is influenced by changes in reluctance encountered by the flux in the core; and 2) to supply internal inductive loading.

Resistive Current – I_R

The purpose of I_R is to supply losses dissipated in the transformer during the test. These losses are mainly driven by hysteresis and eddy current losses in magnetized cores. For the most part, the pattern of I_R, qualitatively, follows I_L. I_R is also unaffected by I_C. Therefore, when interpretation of I_meas is challenged by pattern distortions due to the relative magnitudes of I_L and I_C, I_R can serve as a useful diagnostic indicator.

Capacitive Current – I_C

The objective of I_C is to supply the internal capacitive load. This includes current accounting for the total inductively-coupled capacitive load and the total current leaking to ground.

Exciting Current Components Extraction Featured by Doble Test Assistant

Historically, the empirical data reported by Doble Test Assistant (DTA) included the total current, loss and an indication of whether the current is lagging or leading. The new generation of DTA allows an automatic extraction of total current components through an embedded algorithm with additional data now including inductive, resistive, and capacitive currents, as well as power factor and phase angle (Fig. 2). With that, the diagnostic power of the test is improved, as the data can now be evaluated without impact of capacitive loading.

For instance, the analysis of I_L and I_R should follow the guidelines for lagging I_meas. That is, the expected phase pattern on three- and five-legged core-type and shell-type units is of two high similar readings and a lower reading (2H1L), with the latter obtained on the phase located on the middle leg of the core. Other core types and winding configurations might lead to different patterns.

Figure 2. Exciting current components extraction featured by Doble Test Assistant

Advantages of Single-Phase Exciting Current Components Extraction

• The use of extracted exciting current components enhances our ability to evaluate the condition of electromagnetic system without the influence of capacitive loading.
• Further investigation using the method is expected to allow for a better understanding of the impact the location and the nature of the fault have on each of the current components.
• The latter will ultimately improve the diagnostic power of the exciting current and loss test on power transformers.

More Information:

• Product: DTA Software
• Article: Doble Test Assistant 8 Delivers Greater Diagnostic Power and Instrument Support for Comprehensive Field Testing and Analysis

The post Single-Phase Exciting Current Components Extraction appeared first on Doble Engineering Company.

While acetylene is the most important gas to measure for detecting severe faults, all gasses are important from an incipient fault perspective. The types and quantities of gases that form within the insulating oil will unveil the nature of the fault and determine whether it involves the solid insulation, is a thermal or electrical issue, and whether there is a leak within the sealed system or premature degradation in an open system.

There are many recognized methods for interpreting DGA data, which there is not time to review here, as well as suggested gas limits in guides such as IEEE C57.104-2019 and IEC 60599. Nevertheless, it’s important to remember that allowance must be made for factors such as the type of the dielectric oil involved (silicone, mineral or ester fluids) but a high-level summary of DGA interpretation would be:

• Acetylene usually indicates arcing or a high temperature thermal condition
• To check for partial discharge, look at hydrogen levels
• For low temperature faults, pay close attention to ethane and methane
• Ethylene is an indicator of a high-temperature thermal issue
• In temperate climates, high levels of carbon monoxide are a sign of paper degradation, whereas in hotter climates, high levels of CO can persist without other indicators of paper degradation being present
• High levels of carbon dioxide can indicate general overheating of the paper insulation

A single set of DGA data fails to inform us whether the gas concentrations are stable, increasing or even subsiding, or indeed how long they have been there, if they are associated with a known incident like a transient condition, or when the transformer is stressed in a particular manner. All that is known are the gases present and the concentration of each; this may indicate an issue, but it cannot indicate whether there is an active problem. Therefore, a trend of several data points needs to be established which will inform the asset manager if the gassing is stable, becoming more intense, or if it is progressing from one fault type to another.

Even after having established the DGA trend, as with all diagnostic tests, context is paramount. Know the normal behavior for your asset, its age, and local conditions, such as ambient temperature, loading, transients, harmonics, or other circumstances that would explain the gases in the oil. Comparing gassing of an asset to sister units (if available) can provide additional information. Changes in the gassing levels may have been caused by a change in loading pattern or a through fault. Also consider any maintenance activities that have been performed. Have any repairs been made? What electrical tests have been conducted? If results from several transformers have changed, has there been a change in sampling procedure or the laboratory used?

Under some circumstances degassing of the transformer oil is undertaken; typically, when filling a new transformer or after maintenance which has exposed the core and windings. This inevitably changes DGA values and requires new benchmark tests to reestablish the trend in gas behavior over a period of time (at least 3 months). It’s important to remember that degassing the oil will not fix the underlying cause of the problem, erases the DGA trend and as a procedure is not risk free even when using competent contractors.

In the third and final part of this blog series we’ll look at Oil Quality data and the valuable information that gives us about transformer condition.

Authors:

Simon Sutton has over 25 years’ experience in the electricity transmission and distribution industry predominantly in the cables sector. He has worked in the cable materials supply industry, as the cables policy manager for a transmission utility and in the research sector. His interests also include condition monitoring, diagnostic testing, forensics and asset management. Simon now works as Director of Services for Altanova, a Doble company, and is based in the UK. His responsibilities include business strategy, external relationships and coordination of technical activities around the world. Simon holds a degree and PhD in Physics both from the University of Reading. He is active in International professional bodies representing UK on the CIGRE Study Committee for Materials and Emerging Test Techniques, Convenor of the CIGRE Strategic Advisory Group on Solids and is a member of the editorial board of the IEEE Electrical Insulation Magazine. He is a Visiting Senior Research Fellow at the University of Southampton.

Lance R. Lewand is the Technical Director for the Doble Insulating Materials Laboratory. The Insulating Materials Laboratory is responsible for routine and investigative analyses of liquid and solid dielectrics for electric apparatus. Since joining Doble in 1992, Mr. Lewand has published over 75 technical papers pertaining to testing and sampling of electrical insulating materials and laboratory diagnostics. Mr. Lewand received his Bachelor of Science degree from St. Mary’s College of Maryland. He is actively involved in professional organizations including the American Chemical Society, a representative of the U.S. National Committee for TC10 of the International Electrotechnical Commission (IEC) and ISO TC28, ASTM D-27 since 1989, Chair of ASTM Committee D-27, sub-committee chair 06 on Chemical Tests, secretary of the Doble Committee on Insulating Materials, and a recipient of the ASTM Award of Merit for Committee D-27.

Andy Davies has been working for Doble for 6+ years. His work commenced with 2.5 years in the Middle East; providing asset health indexing and maintenance guidance for over 2400 transformers for a middle eastern transmission company. Since then, he has been involved with support and training for online asset management tools like dobleARMS and INSIDEVIEW, hardware support for portable and field oil testing equipment like Calisto, Myrkos and Domino and provides transformer consultation for customers located across EMEA. Prior to Doble, he worked with an oil services company; that provided oil reclamation and mobile oil solutions that included technical consultation for all generators, HV contractors, transmission and distribution utilities across the UK and Ireland. He has led research into DBDS and Acidity in transformers and their mitigation strategies and has a sound understanding of oil chemistry.

More Information:

• Products:
  • Condition Monitoring
  • Myrkos – Portable Dissolved Gas Analyzer
• Services: Laboratory Services
• Articles:
  • Purchasing a New DGA Monitor? Read the Fine Print
  • The Power of Dissolved Gas-in-Oil Analysis

The post Assessing Transformer Condition – Part 2: Dissolved Gas Analysis (DGA) Carries the Most Weight appeared first on Doble Engineering Company.

Figure 1. Basic Setup for SFRA Ratio Test

Fig. 1 shows the basic setup of the SFRA ratio test. The high-voltage winding is excited by the test voltage applied between the red lead and ground and the secondary voltage is measured between the black lead and ground. The ratio of voltages – calculated by Equation (1) – can be displayed as shown in Fig. 4 by selecting Plot Magnitude (ratio) as shown in Fig. 5.

1. Identifying winding with shorted turn

The ratio closely approximating the ratio of turns can be obtained only at the low frequency (< 200 Hz). The spread or maximum deviation (Δ) between the SFRA ratio traces of different phases is used in detecting the presence of the shorted turn and identifying the defective winding.

Table 1 presents the guidelines for analysis of the SFRA ratio at the frequency near 25 Hz (selected to avoid interference at power frequency).

• The trace of the phase that is abnormally low in comparison to traces of other phases is an indication of failure in the primary winding, i.e., the reduction of the number of turns N₁ reduces the voltage ratio.
• The trace of the phase that is abnormally high in comparison to traces of other phases is an indication of failure in the secondary winding, i.e., the reduction of the number of turns N₂ increases the voltage ratio.

Table 1. SFRA Ratio interpretation in low frequency region

2. SFRA Ratio Analysis in SFRA V6.2

SFRA ratio analysis has been implemented in SFRA version 6.2 since March 2022. The software automatically identifies the trace with abnormal deviation and points out which winding has the shorted turns. For example, a transformer rated 300 MVA, 230/20 kV tripped out of service and SFRA Open-Circuit (OC) tests identify a typical shorted turn defect in Phase A. This defect could be in either the HV winding (Fig. 2) or in the LV winding (Fig. 3).

Figure 2. SFRA HV Open-Circuit Test Results

Figure 3. SFRA LV Open-Circuit Test Results

To determine which winding in the phase A had the shorted turns, the SFRA ratio tests were performed on all three phases (Fig. 4) and SFRA ratio analysis was used to automatically detect the defective phase A and identify the shorted turns located in H1 winding (Fig. 5).

Figure 4. SFRA Ratio Results

Figure 5. Ratio Analyzer window superimposed on result window

3. Summary

The field test experience above has demonstrated the value that the SFRA Ratio test can offer as additional information associated with the winding condition and help rapidly locate the defective winding that can guide further investigative actions. Furthermore, this test does not require any additional investment other than using the existing test set and if performed in junction with the standard SFRA tests, the time of both the test setup and performance of the test will be minimal.

More Information: 

• Product:
  • M5500 – Sweep Frequency Response Analyzer
  • SFRA Software – Sweep Frequency Response Analyzer Software
• Articles:
  • Four Common Mistakes in Sweep Frequency Response Analysis Testing

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