400 A frame, 80 A trip — what the interrupting ratings mean for a feeder circuit
The Siemens 3VA2340-5JQ42-0JA0 is a SENTRON 3VA2 molded case circuit breaker in a 4-pole configuration, built for line-protection duty on distribution feeders. The 400 A frame carries an 80 A thermal-magnetic trip unit, so this breaker is sized for a feeder that normally pulls 80 A but needs the mechanical and interrupting capacity of the larger frame — common in mining or industrial switchboards where a downstream fault could dump serious energy into the breaker. The interrupting ratings tell you where this breaker can sit: 187 kA at 240 V AC, 121 kA at 415 V, 121 kA at 440 V, 75.6 kA at 500 V, and 7.5 kA at 690 V. At 240 V, 187 kA means it safely clears a fault of that magnitude without rupturing — that is a high-capacity breaker for a low-voltage main or a large subfeed where the available fault current is brutal. At 690 V the rating drops to 7.5 kA, so verify the system SCCR before using it on a 690 V line. Thermal derating is published across the full operating range: full 400 A continuous at 40–50 °C, then 375 A at 55 °C, 350 A at 60 °C, 325 A at 65 °C, and 300 A at 70 °C. If this breaker lives in a hot panel — say next to a crusher drive or a transformer — the 55 °C derate to 375 A is the number to use for the BOM, not the 400 A nameplate.
Mounting dimensions and panel fit
The breaker measures 248 mm high, 184 mm wide, and 110 mm deep. That 110 mm depth is the dimension that matters for gland-plate clearance on a deep enclosure — it fits standard 200 mm deep industrial enclosures with room for the rear studs and lugs. The 184 mm width for a 4-pole unit is typical for the 3VA2 frame; verify the bus-bar spacing in your existing switchboard before committing the cutout.
Built-in communication and shunt trip
This variant includes a communication function and a shunt trip release — meaning it can be remotely tripped via a control signal and integrated into a monitoring network. The shunt trip is useful for emergency-stop or undervoltage protection schemes where a PLC or safety relay needs to kill the breaker. The basic switch variant is order code 3VA2340-5JQ42-0AA0 if you need the same breaker without the shunt trip. Maximum power loss is 96 W at rated current — a factor for enclosure thermal calculations. The breaker operates from -25 °C to 70 °C and stores from -40 °C to 80 °C.