Selection criteria for 3VA molded case circuit breakers
The circuit breakers are always dimensioned and selected irrespective of the system type in which they will be deployed.
The circuit breaker is always selected according to the maximum potential short-circuit current in the IT system. The device is selected in accordance with the relevant Icu values of the 3VA molded case circuit breaker.
If the system operator takes measures to ensure that a double-phase-to-ground fault cannot develop on the line side or load side of the circuit breaker, the breaking capacity Icu /Ics remains unchanged in IT systems. If this cannot be ensured, the values in accordance with the standard IEC 60947‑2 Annex H apply for single-pole short circuits.