SENTRON 3VA1112-4EF36-0CH0 — 125 A MCCB for line protection
The Siemens SENTRON 3VA1112-4EF36-0CH0 is a 3-pole molded case circuit breaker (MCCB) rated 125 A continuous at 40 °C, with a 121 kA interrupting capacity at 240 V. It's designed for line protection — meaning it sits on the incoming feeder, not downstream branch circuits. The 125 A frame carries the full load without derating up to 50 °C; at 70 °C it still holds 114 A, which matters for a warm panel top. The interrupting curve drops from 121 kA at 240 V to 75.6 kA at 415 V, 52.5 kA at 440 V, and 11.9 kA at 500 V and 690 V — that's a steep roll-off above 480 V, so verify your available fault current if this feeds a 600 V class panel. The 800 V rated insulation voltage (Ui) gives headroom for the 690 V interrupting rating.
Auxiliary and undervoltage release configuration
This variant ships with an undervoltage release (UVR) and 2 auxiliary switches plus 1 trip alarm switch HQ. The UVR means the breaker trips when control voltage drops — standard for emergency-stop chains or undervoltage protection on motor feeders. The auxiliary contacts give status feedback to a PLC or annunciator without extra wiring. The 30.6 W maximum power loss at full load is the heat you need to vent. In a 76.2 mm wide, 130 mm tall, 70 mm deep footprint, that is manageable with natural convection if the panel is not packed tight. The trip indicator is present.