What this MCCB delivers — and what the ratings mean for your panel
The Siemens SENTRON 3VA1112-5FF42-0AA0 is a 4-pole molded case circuit breaker rated 125 A continuous at 40 °C (derated to 114 A at 70 °C). It carries a TM240 thermal-magnetic release — fixed thermal trip, magnetic adjustment — sized for line protection in distribution panels. The interrupting capacity hits 187 kA at 240 V AC, 121 kA at 415 V, and 76 kA at 440 V; at 500 V and 690 V it still holds 17 kA. That 187 kA figure means it can safely clear a fault at the main service entrance where available fault current is highest — a key spec for SCCR compliance in industrial switchboards. Insulation voltage is rated 800 V (Ui), so it handles 690 V systems without derating the dielectric gap.
Panel fit and integration notes
Dimensions: 130 mm high, 101.6 mm wide, 70 mm deep. The 4-pole width (101.6 mm) matches standard MCCB mounting footprints on DIN rail or panel-mount adapters. Front IP40 protection means it is suitable for enclosed distribution boards where no water ingress is expected. An optional motor drive (Product Extension / Optional / Motor Drive = Yes) allows remote trip or reset — useful for automated restart sequences. The N-conductor protection is set at 50% of the phase rating, which is the common setting for 4-pole breakers in TN systems where the neutral is not fully rated.
Thermal derating — what the temperature table tells you
The breaker holds its full 125 A rating from 40 °C through 50 °C. Above that, it derates linearly: 122 A at 55 °C, 120 A at 60 °C, 117 A at 65 °C, 114 A at 70 °C. If your panel ambient runs above 50 °C, size the breaker for the actual load at that temperature — do not assume 125 A all the way. The maximum power loss is 28.1 W, which matters for thermal budgeting inside a sealed enclosure.