Smart Grid News and Analysis

IoT World Forum 2018
IoT World Forum 2018

New vacuum circuit breakers for higher voltage levels


With the Sion 3AE5, Siemens has enhanced its portfolio of vacuum circuit breakers for medium-voltage power distribution. The new circuit breaker is used as an incoming main in air-insulated medium-voltage equipment. In comparison to the previous model, the Sion 3AE5, at a rated voltage of 17.5 Kilovolt (kV), handles higher rated short-circuit currents up to 31.5 kilo amperes (kA) and can run rated operational currents up to 2500 amperes (A).

The new, wider drive cover offers room for an additional release and thus more flexible options for use. The circuit breaker can be expanded with different release and interlock mechanisms. The electrical closing lockout provides for more safety. As a key component of a switchboard, circuit breakers reliably switch all operational currents and residual currents, ensure the load flow in the network and protect the distribution network and the connected loads against short circuits. Typical areas of application are ring main units and transformer stations, wind power and photovoltaic systems, as well as power distributions in industrial plants.

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. Because no oxidation occurs in a vacuum, the contacts remain perpetually clean and guarantee uniform switching behavior throughout the entire life cycle.

As a result, like all vacuum circuit breakers of the Sion series, the new Sion 3AE5 is especially low-maintenance: up to 10,000 operating cycles are possible under normal ambient conditions between -5°C and 55°C without re-lubrication or readjustment. With servicing procedures, the unit can switch up to 30,000 times. The Sion 3AE5 vacuum circuit breakers are optionally available for fixed mounting or in draw-out technology. Different low voltage plugs or terminal strips facilitate installation. Due to the large selection of pole center distances and jaw widths, along with the comprehensive installation accessories, retrofitting is easy in existing switchboards.