Siemens has developed two new compact vacuum circuit breakers for rated voltages of 12 kV and 24 kV. The Sion Lateral 3AE61 and 3AE63 circuit breakers have a particularly compact design and are more lightweight than comparable products. As the most important element in switchgear, circuit breakers reliably switch all operating and residual currents, secure the load flow in the electrical system and protect the distribution grid and connected consumers against the effects of short-circuits. Unlike gas-insulated switches, vacuum circuit breakers interrupt the arc in a vacuum interrupter. The hermetically sealed vacuum interrupters are generally maintenance-free and independent of environmental influences. Not least, no oxidation takes place in the vacuum, so that the contacts remain permanently clean, thus ensuring consistent switching behavior.
The switches are used in secondary medium-voltage power distribution, for example in ring main units, transformer stations, industrial plants as well as in wind turbines and photovoltaic plants. Thanks to the low volume and special design of the devices, switchgear rooms can have narrower dimensions, making them smaller and more cost-efficient. A wide range of connection options to the high voltage contacts gives plant manufacturers optimum busbar mounting options. The circuit breakers are available for different pole distances as well as for left-mounted or right-mounted drives. The single-phase, encapsulated breakers can conduct rated currents of up to 1250 amperes (A) and manage a rated short-circuit breaking current of up to 25 kA. They require no maintenance up to 10,000 electrical switching cycles under normal ambient conditions between -5°C and 55°C.