ABB Plant Invests in Expanded Production of UHV Bushings

BUSHINGS

BUSHINGS

ABB Plant Invests in Expanded Production of UHV Bushings

The past ten years have witnessed a dramatic spike in interest in UHV, with important projects completed or underway in such countries as China, India, Brazil and Korea, among others. To meet the growing current and large projected future demand in this sector, many equipment manufacturers and test laboratories, especially within China and India, have already invested in new UHV facilities.

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INMR® Q4 2010

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INMR visits the ABB components bushing plant in Sweden, the largest manufacturer of UHV bushings in the world, where an investment of some US$ 50 million has also recently been made to increase production capacity for UHV bushings and to build one of the world’s most sophisticated UHV test facilities.

ExpandEd produCtion

oF

uhV buShingS

abb plant inVEStS

in

ExpandEd produCtion

oF

uhV buShingS

Q4 2010 INMR®

89

BUSHINGS

ABB Plant Invests in Expanded Production of UHV Bushings

The past ten years have witnessed a dramatic spike in interest in UHV, with important projects completed or underway in such countries as China, India, Brazil and Korea, among others. To meet the growing current and large projected future demand in this sector, many equipment manufacturers and test laboratories, especially within China and India, have already invested in new UHV facilities.

88

INMR® Q4 2010

abb plant inVEStS

in

INMR visits the ABB components bushing plant in Sweden, the largest manufacturer of UHV bushings in the world, where an investment of some US$ 50 million has also recently been made to increase production capacity for UHV bushings and to build one of the world’s most sophisticated UHV test facilities.

ExpandEd produCtion

oF

uhV buShingS

abb plant inVEStS

in

ExpandEd produCtion

oF

uhV buShingS

Q4 2010 INMR®

89

Because of the typical dimensions of such bushings, which can be several meters in length, manipulating paper rolls of these diameters is not always practical and therefore an alternative winding method with strips, applied in a sophisticated operation, is used to build up the core. Says Larsson, “it is a time consuming process, but it gives you total control.” Depending on the application (AC/DC) and the voltage level, the optimal paper width is chosen to ensure maximum accuracy and productivity of the winding process and the highest quality.

“It’s a totally different world now. It’s just not good enough for any supplier to simply sell what they had 20 years ago.”

UHV bushing after final assembly now ready for testing.

According to Global Product Manager for Bushings, Ralf Hartings, ABB’s planning for new investments in the field of UHV began more than three years ago, with formal approval given in January 2008. Within only a year and a half from that time, a huge new UHV test laboratory was inaugurated and became a dominant landmark in the Swedish town of Ludvika, one of ABB’s major European business hubs. Much less visible but equally important was the dramatic increase in the size of the workshop devoted exclusively to UHV bushings and which in the past had occupied only a small fraction of the overall Ludvika plant.

more than 20 factories worldwide. Hartings observes that one of the challenges faced by this business in recent years has been to ensure that the product portfolio has kept up with the changed market environment as well as the new focus on transmission super grids and smart distribution. “It’s a totally different world now,” he remarks. “Therefore it’s just not good enough for any supplier to sell only what they had 20 years ago.” For example, he points to the new IEC 60137 (2008) standard for bushings with its requirement for 10% higher AC test voltage and impulse levels than before. He also mentions the industry’s growing need for more robust bushings, able to withstand higher mechanical forces while also offering greater ease of installation.

Hartings works within a division of ABB, Product Group Insulation & Components that supplies components and insulating materials to utilities as well as manufacturers of transformers, rotating machines and HV electrical equipment. Total annnual sales amount One development, however, that has to some 1 billion US dollar spread over yet to be realized in the bushings

90

INMR® Q4 2010

abb plant inVEStS

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business has been the long anticipated changeover in technology away from the classical oil-impregnated paper (OIP) type to the dry resinimpregnated paper (RIP) design. In spite of predictions dating back to the mid 1990s that RIP would eventually become equally important, the bushings market today remains firmly anchored on OIP and especially so for UHV where the appropriate RIP technology has yet to be demonstrated. “Yes, there is a shift to RIP,” says Hartings, “but it is still relatively slow and mainly involves meeting special customer needs for safety, safety and reduced risk of fires and leaks.” Hartings and Workshop Manager, Thomas Larsson, take INMR on a visit through the newly renovated area now devoted exclusively to the manufacture of UHV bushings. The production process begins with preparation of the rolls of the special paper used to wrap the condenser core.

uhV buShingS

Larsson explains that, given the growing business in this sector, the winding capacity has now tripled. All winding machines are housed in special climate-controlled rooms to allow better control over key manufacturing parameters such as ambient humidity. In the case of AC units, the wrapped core is than inserted into horizontal tubes inside a large chamber where impregnation with oil takes place under vacuum over periods that can be days to weeks. Notes Hartings, “these impregnation cycles are based on well-known curves from our industry and also from long ABB experience. The sizes of the cores may have changed but not the basic principles.” After cooling, in-process capacitance tests are conducted

OIP bushings (background) still dominate the market by a factor of at least six to one compared to RIP styles (foreground).

Imposing scale of typical UHV wall bushing is clearly evident from this full size poster placed in the engineering offices at ABB PGIC in Sweden.

abb plant inVEStS

in

ExpandEd produCtion

oF

uhV buShingS

Q4 2010 INMR®

91

Because of the typical dimensions of such bushings, which can be several meters in length, manipulating paper rolls of these diameters is not always practical and therefore an alternative winding method with strips, applied in a sophisticated operation, is used to build up the core. Says Larsson, “it is a time consuming process, but it gives you total control.” Depending on the application (AC/DC) and the voltage level, the optimal paper width is chosen to ensure maximum accuracy and productivity of the winding process and the highest quality.

“It’s a totally different world now. It’s just not good enough for any supplier to simply sell what they had 20 years ago.”

UHV bushing after final assembly now ready for testing.

According to Global Product Manager for Bushings, Ralf Hartings, ABB’s planning for new investments in the field of UHV began more than three years ago, with formal approval given in January 2008. Within only a year and a half from that time, a huge new UHV test laboratory was inaugurated and became a dominant landmark in the Swedish town of Ludvika, one of ABB’s major European business hubs. Much less visible but equally important was the dramatic increase in the size of the workshop devoted exclusively to UHV bushings and which in the past had occupied only a small fraction of the overall Ludvika plant.

more than 20 factories worldwide. Hartings observes that one of the challenges faced by this business in recent years has been to ensure that the product portfolio has kept up with the changed market environment as well as the new focus on transmission super grids and smart distribution. “It’s a totally different world now,” he remarks. “Therefore it’s just not good enough for any supplier to sell only what they had 20 years ago.” For example, he points to the new IEC 60137 (2008) standard for bushings with its requirement for 10% higher AC test voltage and impulse levels than before. He also mentions the industry’s growing need for more robust bushings, able to withstand higher mechanical forces while also offering greater ease of installation.

Hartings works within a division of ABB, Product Group Insulation & Components that supplies components and insulating materials to utilities as well as manufacturers of transformers, rotating machines and HV electrical equipment. Total annnual sales amount One development, however, that has to some 1 billion US dollar spread over yet to be realized in the bushings

90

INMR® Q4 2010

abb plant inVEStS

in

ExpandEd produCtion

oF

business has been the long anticipated changeover in technology away from the classical oil-impregnated paper (OIP) type to the dry resinimpregnated paper (RIP) design. In spite of predictions dating back to the mid 1990s that RIP would eventually become equally important, the bushings market today remains firmly anchored on OIP and especially so for UHV where the appropriate RIP technology has yet to be demonstrated. “Yes, there is a shift to RIP,” says Hartings, “but it is still relatively slow and mainly involves meeting special customer needs for safety, safety and reduced risk of fires and leaks.” Hartings and Workshop Manager, Thomas Larsson, take INMR on a visit through the newly renovated area now devoted exclusively to the manufacture of UHV bushings. The production process begins with preparation of the rolls of the special paper used to wrap the condenser core.

uhV buShingS

Larsson explains that, given the growing business in this sector, the winding capacity has now tripled. All winding machines are housed in special climate-controlled rooms to allow better control over key manufacturing parameters such as ambient humidity. In the case of AC units, the wrapped core is than inserted into horizontal tubes inside a large chamber where impregnation with oil takes place under vacuum over periods that can be days to weeks. Notes Hartings, “these impregnation cycles are based on well-known curves from our industry and also from long ABB experience. The sizes of the cores may have changed but not the basic principles.” After cooling, in-process capacitance tests are conducted

OIP bushings (background) still dominate the market by a factor of at least six to one compared to RIP styles (foreground).

Imposing scale of typical UHV wall bushing is clearly evident from this full size poster placed in the engineering offices at ABB PGIC in Sweden.

abb plant inVEStS

in

ExpandEd produCtion

oF

uhV buShingS

Q4 2010 INMR®

91

apparently designed to automatically perform all operations including drying and the placement of metallic foil so as to ensure fast speed as well as a consistently low spread of test values after winding. After assembly with silicone housings, the DC units are rolled into an adjoining chamber for pressure tests where a dedicated gas is pumped in and then out. Hartings explains that such testing is routine for all gasfilled bushing designs since it verifies the integrity of the insulator-flange interface and also the performance of the rupture disk used to deal with unexpected pressure build up. Ovens for the drying process.

before the core moves to the next stage of production. The assembly of gas-filled UHV DC bushings involves a somewhat different process and is conducted horizontally inside a special clean room isolated from all outside contaminants such as dust or metallic particles. Core winding for 800 kV DC bushings is performed on a new winding machine located outside the UHV production area and which Larsson explains utilizes full width paper, unlike the case for UHV AC bushings. This machine incorporates much proprietary knowledge and was

“We have found that, in the case of DC bushings, field distribution across the unit is determined not only by permittivity but also by resistivity of the material. That’s what makes DC applications so much more demanding.”

Hartings goes on to say that normally ABB supplies complete RIP solutions, however in the case of the highest voltage and current ratings the design solutions are SF6 based. He also emphasizes that for DC, the core is critical to performance in terms of desired distribution of electric field. “For DC, he observes, “we have found that field distribution is determined not only by permittivity but also by resistivity of the core material. That is what makes such applications so much more demanding.” Hartings notes that the demand for UHV DC bushings will likely grow substantially as thinking in the industry today visualizes super grids to handle huge amounts of power moving along transmission corridors.

Wound core of UHV OIP style bushing is wrapped to protect it against moisture after impregnation with oil.

While Hartings reviews all the improvements in manufacturing processes to allow expanded production of UHV transformer and wall bushings, he reserves his greatest praise for the new UHV laboratory, which he claims has been designed to meet all the testing needs of such components as well as HVDC valves. Among the challenges faced in this regard was isolating the structure from all the impact of disturbances in the surroundings that might affect the sensitivity of partial discharge tests conducted to levels as low as 1 pC. Another was ensuring that the huge facility had sufficient capacity

to handle an ever-growing demand for routine and type tests. Says Hartings, “we have designed this building in a way that makes it quite unique in terms of both its scale and also the nature of its test equipment, especially when it comes to DC.” For example, he points out that the whole structure was built as a Faraday cage with an inner lining to separate it electrically from the surroundings. This required overcoming challenges such as insulating the overhead cranes which, while electrically belonging to the inner structure, belong mechanically to the outer structure.

outside the laboratory’s electrical environment and separated from it by a mesh that is part of the inner cage. “We have ensured that there is no electrical connection from the ‘outside world’ to the lab’s ‘inside world’. That means that nothing goes through the walls, including piping and ventilation, all of which have had to be separated by insulation. Moreover, to ensure that testing of any UHV bushing would always place it as the weakest link in the overall insulation, a 70 cu. m oil tank was installed below the floor. Hartings also notes that construction required training the workers to meet

Similarly, the overhead lighting is

Facility for pressure testing of gas-filled UHV DC bushings

18 m long 800 kV DC wall bushing.

Photo courtesy of ABB

92

INMR® Q4 2010

abb plant inVEStS

in

ExpandEd produCtion

oF

uhV buShingS

abb plant inVEStS

in

ExpandEd produCtion

oF

uhV buShingS

Q4 2010 INMR®

93