On-Line Transformer and Battery Monitoring

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Serveron Corp. launched itself in February as the industry’s first provider of full time monitoring services for T&D equipment. Starting with the gas-in-oil sensors developed by a predecessor company, Micromonitors, Serveron offers a complete solution, from instrumentation, to on-line monitoring, to (condition-based) maintenance scheduling and asset management, to risk management. The company also has comprehensive monitoring technology for station battery systems. The complete suite of applications also covers tap changers, arresters, bushings and breakers.

Large Power Transformers:
Note some alarming facts about the T&D infrastructure, and large transformers in particular. The fleet is “graying” — the average age of units now in use is 35 years. Hartford Steam Boiler has data showing an exponential increase in serious failures: 1% of large transformers (1,000 transformers in the US alone) will fail this year, and the failure rate will rise to 2% by 2008.

The average cost of such a unit is $2-3 million and lead time for new ones can exceed a year or more, so a major failure has very significant implications. An early target — powerplant step-up transformers. Any event that could take part or all of a plant’s capacity off-line for a long time becomes even more crucial in today’s climate.

In addition, major savings can be realized with true condition-based maintenance. Since monitoring and diagnostics have not been readily available or cost-effective, utilities now perform maintenance on arbitrary schedules, but estimates are that 30% to 50% of that work is unnecessary. Finally, capital equipment replacements can be prioritized and scheduled in ways that specifically minimize physical and financial risk.

Serveron’s TrueGas™ analyzers monitor the levels of volatile dissolved gases in the insulating oil in large transformers and other oil-filled equipment. Over the life of a transformer, fault gases form due to the degradation of the insulating materials or from the presence of thermal or electrical faults. The type and concentration of these gases are primary indicators of transformer condition and types of faults.

TrueGas analyzers are the only instruments available today that detect and separately analyze trace levels of all eight fault gases. Other instruments detect only a subset of these gases or provide only combined gas data that may not accurately predict equipment failures.

Since serious problems evidence themselves only hours to days before a failure, realtime online measurements and analysis are critical. Test procedures that involve the periodic drawing of samples and sending them to a lab just can’t do the job.

Serveron’s on-site equipment and Web-based analysis software provide continuous monitoring during actual operations, and thus early identification of transformer conditions that require maintenance or that could lead to catastrophic failure of the equipment.

The company will also integrate other sensor data into the system, such as electrical, thermal and mechanical (e.g. acoustic/vibration) parameters.

Battery Systems:
All power plants and T&D substations have large banks of batteries which provide back-up power required for startup and for graceful shut down in the event of an unplanned outage or equipment failure. There can be 50 to 70 truck-battery-sized cells in each bank, for a total of tens of thousands of individual battery cells in an average utility, at hundreds of remote locations. Inspection and maintenance is a major cost, as these systems must function when called upon. (In nuclear plants, they also have to be available, or the plant may have to shut down.)

Serveron’s CellSense™ monitors provide continuous measurements of all key physical and electrical parameters needed to characterize the condition of all individual cells as well as the battery system as a whole. CellSense™ instruments monitor the batteries on-site, and graphical data can be viewed from any remote location using a common browser to access Serveron’s secure web site. With CellSense™ monitoring, battery maintenance and inspection can be reduced from a monthly to an annual activity.

I have a company powerpoint presentation (400kb) that I can send on request, and more information is available on the company’s website:

http://www.serveron.com/

Contact: Jim Moon, CEO 541-330-2350 jim.moon@serveron.com

Pebble Bed Modular Reactor (PMBR)

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The press has recently carried a number of stories about the potential resurgence of nuclear power as an option to deal with both generation shortages and global climate/emissions concerns. Most recently, of course, the Vice-President has raised it.
[e.g., Boston Globe, 11 Feb; Business Week, 23 Apr; WSJ, 2 May — I have copies]

One of the more remarkable “new” technologies mentioned is the Pebble Bed Modular Reactor (PMBR), actually an old idea. In the heyday of reactor development, helium gas cooled designs were pursued by the U.S. (using a fuel block concept) and by the Germans, who used a “pebble” fuel configuration. The US program fell apart in the mid-90’s, though General Atomics kept pushing it as a means to burn up Soviet plutonium stockpiles. The Japanese and Chinese also continue to have programs, each with operating developmental reactors.

While the Germans dropped their program, their pebble idea later took hold with research in China and Indonesia, and finally in South Africa, where the story picks up speed. Eskom, the huge utility there, faced serious pollution problems with bad coal, and they needed smaller power plants that could be located near the coast, closer to population centers. The country also wanted to create high tech industry and jobs.

Eskom set up a new venture called PBMR (Pty) Ltd, and attracted development funds from the their government, British Nuclear Fuel (BNFL), and Exelon.
BNFL 22.5%
Eskom 30%
Exelon 12.5%
Industrial Development Corp of S. Africa (IDC) 25%
(the remaining 10% is reserved for black empowerment investment)

What is PBMR? From the company’s website:

“The PBMR is a helium-cooled, graphite-moderated high temperature reactor (HTR).

The PBMR consists of a vertical steel pressure vessel, 6m (19,7 ft) in diameter and about 20m (65 ft) high. It is lined with a 100cm (39 inch) thick layer of graphite bricks, which serves as a reflector and a passive heat transfer medium. The graphite brick lining is drilled with vertical holes to house the control rods.

The PBMR uses silicon carbide and pyrolitic carbon coated particles of enriched uranium oxide encased in graphite to form a fuel sphere or pebble about the size of a billiard ball. Helium is used as the coolant and energy transfer medium to a closed cycle gas turbine and generator system. When fully loaded, the core would contain 330 000 fuel spheres and 110 000 pure graphite spheres. The latter serve as an additional nuclear moderator.”

A major appeal is the inherent passive safety of the design. From the website:

“How safe is the PBMR? The PBMR is based on a simple design, with passive safety features that require no human intervention and that cannot be bypassed or rendered ineffective in any way. In all existing power reactors, safety objectives are achieved by means of custom-engineered, active safety systems. In contrast, the Pebble Modular Reactor (PBMR) is inherently safe as a result of the design, the materials used, the fuel and the physics involved. This means that, should a worst case scenario occur, no human intervention is required in the short or medium term.”

Another is “modularity”, at a scale of ~100 MW. Also, without the huge burden of auxiliary systems and containment, it should be relatively cheap to build.

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The website is very comprehensive, so no need to try to paraphrase it here.
http://www.pbmr.co.za/

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Questions remain, of course. The fuel elements must be well made, and the problem of spent fuel disposal is still hugely unresolved, especially in the US. On the regulatory front, the NRC is being urged to move rapidly to develop a new unique set of licensing criteria that would be appropriate for this inherently safe design, as the old framework simply doesn’t apply. One has to wonder, though, if not-invented-here will hinder progress in the US.

Here’s an Feb 2001 NRC “Fact Sheet” about the many different “next-generation reactors” on their plate:
http://www.nrc.gov/OPA/gmo/tip/fsadvancedrx.html

The DOE Office of Nuclear Energy has it’s Generation IV Initiative, which seems to be taking the view that certification (much less deployment) of some yet-unidentified new small modular reactor technology won’t happen til 2030. A two-year “Roadmap” effort was announced last November. Argonne and Idaho are the lead labs in the program. http://gen-iv.ne.doe.gov http://www.ne.doe.gov/

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Exelon has started the process of education in Washington and around the country. See their congressional testimony available on the Nuclear Energy Institute’s website:
http://www.nei.org/index.asp?catnum=2&catid=4

Meanwhile, in March PBMR let a contract for the design of the fuel fabrication plant:
http://www.ems.co.za/news/news_pmbr.htm

Contact: Ward Sproat, Exelon Nuclear
610-765-5930 edward.sproat@exeloncorp.com