What this MCCB carries and where it fits
The Siemens SENTRON 3VA2340-5HN42-0CL0 is a 4-pole molded case circuit breaker (MCCB) rated for 400 A continuous current at 40 °C, designed for line protection in distribution panels and industrial switchboards. Its interrupting capacity reaches 187 kA at 240 V, 121 kA at 415 V and 440 V, 75.6 kA at 500 V, and 7.5 kA at 690 V — so it handles high-fault-current service entrances and large motor branch circuits without cascading upstream. The 400 A frame holds the rating across 40–50 °C ambient; above that it derates linearly to 340 A at 70 °C, which matters when the breaker sits in a crowded enclosure with limited airflow. This variant ships with an undervoltage release (UVR) and a full auxiliary switch complement: two auxiliary switches, one trip alarm switch, and one electrical alarm switch (HQ design). The UVR trips the breaker when control voltage drops below a threshold — standard for emergency-stop circuits or undervoltage protection on motor feeders. The auxiliary and alarm contacts give the PLC or SCADA a positive status of the breaker position, not just a shunt-trip signal.
Physical fit and panel integration
Dimensions are 248 mm high, 184 mm wide, and 110 mm deep. The 184 mm width is the standard 4-pole MCCB footprint for this frame size — it occupies four 45 mm module spaces on a DIN rail or a direct-mount backplate. Depth of 110 mm leaves clearance for rear-connected busbars and cable lugs inside a typical 600 mm deep enclosure. The breaker accepts front-mounted rotary handles or motor operators from the SENTRON accessory family.
What the ratings mean for your circuit
The 400 A continuous rating at 40 °C is the breaker's thermal-magnetic or electronic trip threshold for overload protection. The interrupting ratings (187 kA at 240 V, 121 kA at 415 V, 75.6 kA at 500 V, 7.5 kA at 690 V) define the maximum fault current the breaker can safely clear at each voltage level. At 690 V the 7.5 kA rating is relatively low — if your system has a higher available fault current at that voltage, you need a current-limiting upstream device or a different frame. The thermal derating table (385 A at 55 °C, 370 A at 60 °C, 355 A at 65 °C, 340 A at 70 °C) tells you the actual ampacity when the breaker is in a warm panel; never size a feeder at the 40 °C rating if the ambient inside the enclosure exceeds that.