Upstream protection of switch disconnectors

Switch disconnectors are not equipped with an integral overload or short-circuit release. For this reason, a molded case circuit breaker or a fuse must be installed upstream of every switch disconnector.

The coordination tables given below contain the following information:

Protection of 3VA1 switch disconnectors at 50 / 60 Hz by a 3VA1 molded case circuit breaker


More combinations can be found on the Internet.

Combinations with other protective devices can be configured at any time by means of SIMARIS design or using the characteristics maximum let-through energy I2tmax and maximum let-through current Ic max of the 3VA1 switch disconnector. You will find these characteristics in the technical product data sheets and in the table in chapter Overview of 3VA1 as switch disconnectors.


In the event of a fault, all switching devices in the affected branch must be function-tested (see Regular maintenance).