World record: Siemens furnace switchgear achieves rated currents of 4,500 amperes

The Simetal Sivac-X 4K furnace switchgear from Siemens has reliably switched a rated current of more than 4,500 amperes with a single circuit breaker in the test laboratory during the course of a successful type test according to IEC 62271. This is significantly more than conventional furnace switchgears achieve. The switchgear has a rated voltage of 40.5 kilovolts, and can supply electric arc furnaces with power up to 300 MVA. The lightning impulse voltage is 200 kilovolts, which also makes the switchgear suitable for the North American market. The switchgear has achieved the fault arc qualification of IAC A FLR of 40 kA/1 s, thus also meeting the highest demands for personnel safety. The core component is the 3AH4 medium-voltage circuit breaker, which has a life cycle of up to 120,000 switching cycles. The type test according to IEC 62271-200 was performed by the CESI group in Mannheim and Berlin.

The Simetal Sivac-X 4K switchgear is designed to meet the extreme requirements of high-power electric arc furnaces, and ensures a reliable power supply as well as safe plant operation. Long maintenance intervals of up to 10,000 switching cycles increase availability and reduce operating costs. The 3AH4 range of frequency circuit breakers are designed for use under extreme environmental conditions. These include high temperatures, high air pollution, unstable operating currents, frequent short-circuit releases, and operating cycles with more than 100 switching cycles per day. For this reason, the circuit breakers have a rugged, insulated support design, and are equipped with freely accessible vacuum interrupters. This enables the interrupters to be replaced easily at the end of their service life of about 30,000 switching cycles.

The circuit breaker is specifically designed so that air can flow freely along the heatsinks. This enables the switching device to operate at up to 4,500 amperes in an ambient temperature of up to +40°C without forced cooling. The drive for the 3AH4 circuit breaker range is designed for up to 120,000 switching cycles over its entire life cycle.

About 400 furnace switchgear systems of the Simetal Sivac-X range are in use worldwide. Siemens offers switchgear for operating voltages ranging from 15 to 40.5 kilovolts and rated currents from 1,250 amperes to meet the specific requirements of electric steelmakers. According to the specific circumstances in the electric steel plant, the switchgear can be designed as an open unit with a permanently installed furnace circuit breaker, as a two-field system in a metal enclosure with a permanently installed circuit breaker, or as a single-field solution in a metal enclosure with a withdrawable furnace circuit breaker mounted on a traveling carriage. The range of products also includes the customized protection circuit, which is essential for the operational safety of the vacuum circuit-breakers and connected components. The arcing-fault tested design, the metal encapsulation, interlocks, the capacitive voltage testing system and the IP4X degree of protection ensure maximum safety for personnel.

The first 3AH4 furnace circuit breakers, with rated currents of 3,150 and 4,000 amperes respectively, are in use in steel works in Germany and Turkey. The first 4,000 ampere switchgear is currently being delivered in the U.S.

Further information about solutions for steel works, rolling mills and processing lines is available at: http://www.siemens.com/metals

A picture accompanies this press release. You can find the picture on the Internet at: http://www.siemens.com/mt-picture/IMT201205158

(The Simetal Sivac-X 4K furnace switchgear from Siemens achieves rated currents of 4,500 amperes. It supplies electric arc furnaces with power of up to 300 MVA)

Sivac-X is a registered trademark of Siemens AG and/or one of its subsidiaries in some countries.

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Based on Siemens (Industry Sector, Metals Technologies) information