At the Elektrotechnik trade fair in Dortmund Siemens Power Transmission and Distribution (PTD) unveiled a new vacuum circuit-breaker. The circuit-breaker with the designation Sion is designed for use in all common versions of medium-voltage switchgear. It will be available from the beginning of 2006 as a complete series for rated voltages from 7.2 kV to 24 kV with a short-circuit breaking current up to 40 kA and rated currents up to 3150 A. Thanks to ingenious utilization of its insulation material, this circuit-breaker sets new standards for air-insulated vacuum circuit-breakers. This results in smaller widths and depths than is the case with fully-insulated circuit- breaker versions. Identical measurements and connection dimensions over several voltage levels reduce planning costs and allow circuit-breakers to be exchanged rapidly. Thanks to its compact design, the circuit-breaker can be integrated easily in the power circuit-breaker space as a complete slide-in module.
The vacuum circuit-breaker fulfills all requirements for use in power distribution systems, and has been tailored to meet the needs of power supply companies as well as those of industry. The circuit-breaker can be assembled in modular form using a number of different built-in packages, such as drawer, contact arms, bushings and shutters. Its dimensions make it possible to install the circuit-breaker in almost any existing system. Overall depths of 370 mm for voltages from 7.2 kV to 17.5 kV and 420 mm for 24 kV also ensure that space saving switchgear bays can be designed. Due to the compact design less converted space is needed for new systems. The low-voltage interface can be opened separately and is attached to the circuit-breaker in a readily accessible position. In this way, work can be carried out easily at the secondary terminal conveniently and without loss of time. The new vacuum circuit-breaker can perform up to 10,000 switching cycles without maintenance. According to Siemens, it has a total mechanical service life of up to 30,000 switching cycles. It fulfils the requirements of IEC 62271-100 and is also tested in accordance with the relevant parts of system specifications IEC 62271-200.
Vacuum switching technology is especially suitable in applications in electrical power supply where dependability, high switching frequency and low maintenance are called for. Vacuum circuit-breakers can be used universally as switching devices in medium-voltage networks for controlling and switching operating currents and short-circuit currents.