High voltage power transformers: Powerful health insurance
by Julia King
This article originally appeared in the May 2007 issue of IEC e-tech.
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Health is important to most of us. If we don't keep our bodies fit and well, they will let us down sooner than they should. They need food and drink to function, exercise to keep them working in optimum condition, and, as they get older, regular health checks.
It's exactly the same with the generation, transmission and distribution networks that help provide the electricity on which the modern world depends. Although transformers are probably not something most of us think about regularly, their health is also vitally important to us all. These are the workhorses that underpin transmission networks, petrochemical plants and much of big industry and that keep hospitals and airports functioning at full strength.
These highly-efficient units allow power to be transmitted over long distances. Failure of just one unit can have immensely damaging consequences to its owner on an economic front, to the public because of our dependence on power and even to the environment. Each transformer in a small network may cost EUR 10 000, while a large transformer could cost considerably more, into the millions.
Viewed against the rapidly-changing world of high technology β the average PC is obsolete within 3-4 years β these transformers are laggards. They can have a working life of some 30-40 years, and the principle of the device was demonstrated by Faraday right back in 1831! Yet this does not mean that the underlying technology is static.
Consider the fluid dielectrics (electrical insulators) used in high voltage or high power transformers. For years, PCB (polychlorinated biphenyl) was used as the liquid in which the windings, an essential part of the device, were immersed to keep them cool. PCB is highly stable and non-flammable, making it eminently suitable for use in transformers, particularly those used inside buildings.
Unfortunately it also turned out to pose significant hazards to health and to the environment and was banned from use in new products in the late 1970s. Even so, it is estimated that there are still some 30 million units in use worldwide that employ PCBs as the dielectric. Their disposal poses a significant problem.
The original insulating liquid, mineral oil, has also started to produce problems in the last few years. This is quite probably to do with radical changes introduced to production methods for oil since around 1990, in terms of refining and blending processes.
Within the last two years or so, a corrosive compound in the oil, DBDS (DiBenzylDiSulphide) has been identified. This attacks the copper in the transformer to form copper sulphide deposits on copper contacts, on paper-covered conductors and on bare contacts. The so-called 'corrosive sulphur' problem reduces the insulating properties of the dielectric. This could lead to arcing, potentially causing explosion and/or fire within the transformers and reactors.
Problems present opportunities
"While both sets of problems provide headaches for manufacturers and users, they also provide a significant opportunity for technical development", says Vander Tumiatti, managing director of Sea Marconi Technologies. The company was set up in Torino, Italy, in 1968, to provide specialized environmentally-based diagnosis and decontamination services and facilities to customers in the area of energy-related products.
Sea Marconi currently has 63 employees but still retains a strong family feel. Tumiatti originally founded the company with his wife, who is now the group's finance and administration manager. Their two daughters are also employed in the business, one as group marketing manager, the other, who is a chemist, as a quality control assistant. The company has expanded and has set up further operations in Southern Italy, in France, in Spain and in South America. It has more than 3 000 customers worldwide.
"Sea Marconi is like a third party. It sits between the manufacturer and the users", comments Tumiatti. "We add value for our customers and aim to provide the best quality of service available right now".
Tumiatti is also assistant secretary of IEC TC 10, Fluids for electrotechnical applications. One of the oldest-established TCs (it was originally set up in 1924), this technical committee is concerned with fluids and gases used as dielectrics.
Combining standardization with service provision
How does Tumiatti see his dual role? "Standardization is important to improve the quality of products and services", he says. He adds: "The role of the SME [small to medium enterprise] is very important for the market. It helps to improve value. Standards are like a frontier that help both the producer and the consumer facilitate industrial activity."
He also believes that the production of standards that aim to prevent environmental risk during the production and operational lifetime of a piece of equipment, and that carry that through to the end of life disposal of the equipment, are important for SMEs such as Sea Marconi. "Life cycle management presents us with a significant opportunity for product development", says Tumiatti.
He adds: "The use of IEC standards helps to produce the best quality of service. Transformers must conform to standards and the customer needs to know that all of the parameters of his product are satisfactory."
These parameters can range from the numbers of particles permitted and gases to what happens when units are transported. Do some elements of the system suffer shock? Does any element of particle count change or any other potentially harmful change occur?
The problem of corrosive sulphur has presented a unique opportunity both to TC 10 and to Sea Marconi. "Until now there has not been an IEC standard because this was a new problem", says Tumiatti. It was proposed in 2005 that a working group be set up to look at the problem. "We have to agree on standards, first of all to detect the problem and then to prevent it."
Although no standard has been agreed yet, the work that Sea Marconi has done on the problem puts it in a perfect position to be able to give advice to anyone with a problem related to corrosive sulphur. Sea Marconi has worked with the University of Missouri at Rolla in the US to develop a technique known as IFED (Integrated Fingerprinting and Elemental Diagnostics). This allows compounds and/or corrosive contaminants to be identified and quantified.
Sea Marconi's own work and access to others' findings, have enabled the company to produce systems and technologies designed to prolong the life of transformers in as green a way as possible. Sea Marconi has also developed maintenance techniques designed to spot problems that will occur in the future unless remedial action is taken.
The company has three main lines of business: a diagnostic coverage and inventory process that can determine the likely presence of corrosive sulphur compounds in oil, a low-temperature process that can detoxify and dehalogenate PCBs without requiring the transformers to be drained of their oil, and an on-site closed circuit depolarization and decontamination program.
Tumiatti has no doubt about the strategic role that the IEC plays in helping to make the world a better and safer place in which to live and work. βThe role of the IEC is very important. It allows a number of people to share their knowledge and that results in production of a solution in the shortest possible time,β says Tumiatti. "Both humans and the environment must surely benefit from this collaborative working. No individual company working on its own could produce the same kind of results in a similar timescale."
Source: International Electrotechnical Commission (IEC).