MCCB for 400 A feeder protection
The Siemens SENTRON 3VA2340-5JQ42-0DH0 is a 4-pole molded case circuit breaker (MCCB) rated 400 A at 40 °C, designed for line protection in distribution panels. With a maximum frame rating of 4 000 A and a minimum setting of 600 A, this breaker covers heavy feeder and main-switch duty. The 187 kA breaking capacity at 240 V and 121 kA at 415 V means it handles high-fault-current service entrances without cascading upstream — a key spec for industrial switchboards where fault current runs high. At 690 V the interrupting rating drops to 7.5 kA, so verify the system voltage against the curve.
Thermal derating and power dissipation
This MCCB holds 400 A continuously up to 50 °C ambient. Above that it derates linearly: 375 A at 55 °C, 350 A at 60 °C, 325 A at 65 °C, and 300 A at 70 °C. If the panel ambient runs above 50 °C, size the breaker for the derated current, not the nameplate. Maximum power loss is 98.5 W — that heat stays inside the enclosure, so factor it into the panel thermal budget. The operating temperature range is -25 °C to 70 °C; storage spans -40 °C to 80 °C.
Integrated auxiliary and release options
This variant ships with 2 auxiliary switches plus 1 trip alarm switch (HQ design), and an undervoltage release (UVR). The UVR trips the breaker when control voltage drops below the dropout threshold — standard for safety disconnects on motor feeders or emergency-stop chains. Communication function is built in, so it can report status back to a PLC or BMS without an add-on module. The trip indicator is present, and the trip unit is adjustable from 80 A to 400 A full-scale, with no voltage-trigger function.
Panel fit and wiring
Dimensions: 248 mm high, 184 mm wide, 110 mm deep. That's a 4-pole MCCB footprint — roughly 7.24 × 9.76 × 4.33 inches. Mounts on a DIN rail or directly to a backplate via the integral mounting points. The 110 mm depth leaves clearance for rear-connected busbars or cable ladders. The base switch variant is 3VA2340-5JQ42-0AA0, meaning this -0DH0 version adds the aux switches and UVR as factory-fitted options.