Page 1

BUSHINGS

New Production Base in China for Transformer Components & Bushings


BUSHINGS

New Production Base in China for Transformer Components & Bushings In 1992, ABB Hefei Transformer Co. represented ABB’s first joint venture for power transformers in China, becoming a wholly owned subsidiary of the multinational engineering giant five years ago. Located in Anhui Province and focused mainly on transformers for 220 kV, it also produces transformers for 110 kV and 330 kV with an annual capacity of some 25000 MVA.

Photo: INMR ©

The company is organized into three separate product groups that, apart from power and distribution transformers, also manufacture a range of related insulation materials and components such as bushings, on-load tap changers and oil treatment equipment. At the end of last year, this product group (PGIC) was relocated to a new 30,000 sq m. facility and is now gearing up production to meet most of the condenser bushing needs of ABB’s HV transformers in Hefei and to supply other customers as well. INMR visits the PGIC Division to report on the progress of this latest ABB investment in China.

80

INMR® Q3 2010

nEw produCtion BasE

in

CHina

for transformEr

 PREVIEW 

ComponEnts & BusHings


Starting this year, ABB will supply the large part of its domestic demand for HV power transformer bushings from its own new factory situated in the same city as its transformer factory. According to Technology Manager, Rolf Berglund, a Swede now stationed in Hefei and who has helped coordinate the transfer of manufacturing know-how for these components, the recently-built facility is expected to become one of the most sophisticated centers for bushings production in China. For example, Berglund points to two new paper winding machines just recently installed, which he claims are equipped with the latest technologies available anywhere. Henrik Nordén and Fredrik Moraeus are ABB specialists who have come to Hefei on a project to assist in optimizing the start-up. Says Nordén, “what makes our new winding machines different from those used by some other suppliers in our industry is their level of sophistication in terms of allowing for simultaneous wrapping and drying with very high

efficiency. This means that finished condenser cores can move as rapidly as possible to assembly with no need for additional drying.” Nordén explains that a bushing’s tan delta correlates closely with the presence of any internal moisture and therefore the drying elements built into each machine are programmed to attain the vital drying while maintaining a high productivity. Another key element of the technology of the two new winding machines, adds Nordén, lies in their ability to achieve very precise placement of the metal foils that provide for the bushing’s internal field grading. These must be programmed for each wrapping process based on such considerations as the type of bushing and its relative dimensions. Once a condenser core has been wrapped, Nordén explains that it is assembled into its external housing (typically porcelain) and both oil reservoir and flange hardware are attached. The next step is applying

“What makes our new winding machines different from those used by some other suppliers in our industry is their level of sophistication in terms of simultaneous wrapping and drying with a very high overall efficiency.” Overview of bushings production area at new Hefei plant.

nEw produCtion BasE

in

CHina

for transformEr

ComponEnts & BusHings

 PREVIEW 

Q3 2010 INMR®

81


New winding machine for 245 kV bushing cores being set-up for production run.

Assembled bushing is subjected to compression before and after filling with oil. (middle left)

Typical elements that make up a finished OIP bushing. (middle right) Photo: INMR ©

sufficient axial pressure to achieve a bushing structure that will withstand stresses in service during the life time of the transformer. Before a wound condenser core is impregnated with mineral oil, the assembled bushing is subjected to vacuum to remove all air. Then, once a pre-set pressure has been attained, filling with oil begins. Both processes

82

INMR® Q3 2010

take place while the bushing is suspended from a production platform and this is followed by a mandatory 12-hour oil pressure test, as specified in IEC 60137. After this test has been completed, capacitance, dissipation factor and partial discharge are measured and oil quality sampled to ensure that any problems during testing (e.g. an

nEw produCtion BasE

in

CHina

for transformEr

 PREVIEW 

internal flashover) have not caused an oil problem. The ultimate goal of all the pre-start up work is to ensure efficiency at each stage. Says Nordén, “what we are really aiming for is to optimize the entire process, from wrapping of the conductor tube all the way to impregnation with oil and final testing.” According to Bushings Product

ComponEnts & BusHings


Manager, DaNan Yao, the current capacity of the new operation is estimated at about 700 units per month but this will grow as eventually there will be two separate production lines for OIP bushings – one for voltages up to 245 kV and the second up to 550 kV. Another production area of the new plant is devoted to assembly of resinimpregnated (RIP) dry bushings up to 123 kV for both oil to oil and oil to air applications. These are made using cured epoxy cores imported from ABB’s operation in Switzerland and fitted into porcelain or composite insulator housings produced locally. Yao points out that, aside from being lighter and having superior mechanical performance versus the OIP design, RIP styles offer other important advantages in terms of being maintenance-free with no need to monitor oil levels and quality. He also notes that, unlike OIP bushings, the RIP type can be installed right away and in any configuration, without need for special handling.

Vacuum and oil filling of assembled bushings (right). Sample of oil is taken to ensure it has not been damaged during electrical testing.

“The Chinese market for bushings is still very much dominated by OIP units equipped with porcelain since they have a lower purchase price.”

nEw produCtion BasE

in

CHina

for transformEr

ComponEnts & BusHings

 PREVIEW 

Q3 2010 INMR®

83


Larger of the two HV labs in ABB’s new Hefei factory.

84

INMR® Q3 2010

nEw produCtion BasE

in

CHina

for transformEr

 PREVIEW 

ComponEnts & BusHings


Production area for oil treatment equipment.

RIP cores on both sides of an assembled RIP bushing. Photo: INMR ©

Typically, RIP bushings require different dimensions for their porcelain housings compared to OIP units of the same voltage rating and the flanges are also different. Yao notes that, while present plant capacity is divided about equally between OIP and RIP, the growth will probably come mainly on the OIP side. The Chinese market for bushings, he observes, is still very much dominated by OIP units equipped with porcelain since they have a lower purchase price. The new Hefei bushings factory has two separate HV laboratories, with the larger one equipped with a 2400 kV impulse generator capable of performing all routine tests on bushings of 245 kV and higher, as required in the Chinese standards. Bushings are not the only major product group at the new plant. Work is underway to complete a facility for de-gassing and treating oil used in transformer applications while an adjoining section has been devoted since November to manufacturing two types of on-load tap changers. 

Final testing of assembled on-load tap changers.

nEw produCtion BasE

in

CHina

for transformEr

ComponEnts & BusHings

 PREVIEW 

Q3 2010 INMR®

85

New Production Base in China for Transformer Components & Bushings  

INMR Article- New Production Base in China for Transformer Components & Bushings

Read more
Read more
Similar to
Popular now
Just for you