The main switch of an electrically driven traction unit combines the transformer with the catenary via the pantograph. If the switch fails, the train stops. For its new AC vacuum circuit breaker Schaltbau has thus selected a technology capable of achieving the highest degree of availability: the CVB is not pneumatically but electrically operated; its switching power is obtained from a constantly loaded spring.

Although all new main switches brought onto the market are equipped with vacuum tubes, they are usually operated via pneumatic switching elements.

Pneumatic systems are more costly to integrate than purely electrical systems and are additionally at risk of freezing at low temperatures. For this reason, when creating the new AC vacuum circuit breaker, the development team from Schaltbau particularly wanted to design it for electrical operation.

Doing without pneumatics means that there are no costs for construction and materials such as filters, shut-off valves, pipes, seals etc. as they occur with the procurement of pneumatic switches.

But even electrically operated main switches can fail if they are obliged to obtain their entire switching power from the vehicle batteries. For this reason Schaltbau utilised a loaded spring which ensures that the motor vehicle is reliably connected to the electricity network, even if it has not been used for a long time and its batteries are almost completely discharged.

With the CVB, Schaltbau offers both manufacturers and operators of electric trains a component that has the ideal technical requirements for operation throughout the vehicle’s entire service life and significantly reduces the usual cost of maintenance.