What this MCCB is and what the ratings mean for your panel
The Siemens SENTRON 3VA2340-5JQ32-0AD0 is a 3-pole molded case circuit breaker (MCCB) rated for line protection, meaning it sits at the feeder or main distribution point in a panel to protect cables and busbars from overload and short-circuit faults. Its full-scale current rating is 400 A, and it carries an adjustable thermal-magnetic trip unit with an initial setting value of 80 A, so you set the actual pickup to match your downstream load. Breaking capacity is the headline number that decides whether this breaker clears a fault without welding its contacts or rupturing the case. At 240 V it interrupts 187 kA; at 415 V and 440 V that drops to 121 kA; at 500 V it's 75.6 kA; and at 690 V it's 7.5 kA. Those are the maximum prospective fault currents it can safely break at each voltage level — spec the available fault current at your service entrance against these numbers, not the 400 A load rating. Thermal derating matters when the breaker lives in a warm enclosure. It carries the full 400 A continuously at ambient temperatures up to 50 °C. At 55 °C you must derate to 375 A; at 60 °C to 350 A; at 65 °C to 325 A; at 70 °C to 300 A. If your panel ambient runs above 50 °C, size the breaker one frame step higher or plan for the derated current. Maximum power loss at rated current is 96 W. That's heat that stays inside the enclosure — factor it into your thermal budget alongside other components, especially in a sealed, non-ventilated panel.
Panel integration and footprint
The breaker measures 248 mm high, 138 mm wide, and 110 mm deep. That 110 mm depth (4.33 in) is the dimension that determines gland-plate clearance and whether it fits a shallow backpanel enclosure.
Lifecycle and sourcing posture
It ships with three auxiliary switches (HQ configuration) factory-installed — no need to add a separate aux switch block for status feedback to a PLC. The basic switch variant 3VA2340-5JQ32-0AA0 is the same breaker without those aux switches, if your BOM calls for the base version.
Operating environment limits
Operating temperature range is -25 °C to 70 °C; storage range is -40 °C to 80 °C. The storage limit governs handling during transport and warehouse hold — the breaker can sit in a cold truck or hot warehouse within that range without damage. The operating limit is what the breaker sees while carrying current.