Vacuum circuit breakers for special applications
Vacuum circuit breakers provide safe and reliable medium-voltage power distribution and stand out for their long service life. In addition to standard applications in medium-voltage power distribution, our portfolio also covers applications for specific requirements in the generator or rail fields, for example.
Designed for tough conditionsGlobal power requirements continue to grow, so do the technical demands on power supply systems. Our vacuum circuit breakers for medium-voltage power distribution are designed to withstand huge loads – reliably and almost entirely maintenance-free, throughout their entire life cycle. This applies especially to generator applications in energy utility and industrial companies and applications that require very high switching rates.
Vacuum circuit breakers for generators
Type tests as specified in IEC 62271-100 are performed as a rule for all Siemens circuit breakers. Generator circuit breakers are additionally tested in accordance with IEEE C37.013 or IEC / IEEE 62271-37-013. This standard is the only standard worldwide to take into account the increased requirements which the devices are subjected to when switching generators. As a result the standard has been enhanced to a Dual Logo IEEE/IEC leading standard.
A number of selection criteria are typically considered when choosing the right vacuum circuit breaker, including rated voltage, rated current, parameters of system-supplied and generator-supplied short circuits, and design. We can offer a range of prefabricated generator circuit breaker types, or build them to meet your precise requirements.
3AK7 vacuum circuit breakers
Vacuum circuit breakers in the 3AK7 series are available in versions from 7.2 to 17.5 kV. The vacuum circuit breakers are very compact, with a distance between pole centers of just 210 or 280 mm, and they’re perfectly suited for use in medium-voltage switchgears thanks to their high mechanical strength and low space requirement. High-voltage and generator versions are available with the same dimensions and can be used for smaller generator switching applications in accordance with IEEE specifications up to 50 kA, and also for high-voltage applications.
3AH3 vacuum circuit breakers
The powerful 3AH3 vacuum circuit breakers were the first 63- and 72-kA vacuum circuit breakers on the market tested in accordance with IEEE C37.013 for load currents up to 12,000 A and short-circuit currents up to 100 kA. In addition to the standard designs, we can also offer phase-segregated versions with separate switching units. The low resistance in the main current path allows the 3AH3 vacuum circuit breaker to be used with operating currents of up to 6,300 A with no forced cooling, or up to 8,000 A with forced cooling. These modular vacuum circuit breakers can also be installed horizontally using special cooling elements and are suitable for retrofitting in existing systems.
Vacuum circuit breakers for high switching sequences
In the industrial field in particular, there are applications that require high to very high switching sequences. Switching in arc furnaces, for example, demands more than 100 switching sequences per day. This requires sturdy, powerful vacuum circuit breakers that can manage these tough demands – like the vacuum circuit breakers in our 3AH4 series.
3AH4 vacuum circuit breakers
The compact vacuum circuit breakers in the 3AH4 series are designed for up to 40.5 kV, and can handle up to 120,000 switching sequences. With minimal maintenance required – greasing the drives after 10,000 switching sequences and changing the vacuum tubes after 30,000 – these circuit breakers stay reliable throughout their entire service life, despite the tough mechanical demands they face. An extensive range of accessory options like remote access means the vacuum circuit breakers are flexible to use and operate.
Vacuum circuit breakers for railway applications
The electricity supply to railway systems calls for circuit breakers with special characteristics. Not only are single or two-pole circuit breakers usually needed for supplying traction current, the stringent demands for operational safety and number of switching sequences also far exceed those of regular applications. In addition, using single-phase rail systems creates tougher demands in terms of dielectric strength.
3AH47 vacuum circuit breakers
The 3AH7 vacuum circuit breakers comply with standard EN 50152-1 and are therefore perfectly suited for use in rail applications involving grid frequencies of 16.7, 25, 50 or 60 Hz. Depending on the version, they can be used as master vacuum switches on locomotives or for stationary traction current supply. Depending on the version, the 3AH47 vacuum circuit breakers can handle up to 60,000 switching sequences. Their compact design means the control panels can be narrower.