What this MCCB carries and where it fits
The Siemens 3VA2340-5JQ42-0BC0 is a SENTRON molded case circuit breaker (MCCB) rated 400 A continuous at 40 °C, with a 4-pole configuration for three-phase-plus-neutral line protection. Its interrupting capacity reaches 187 kA at 240 V and 121 kA at 415 V, so it handles high-fault utility feeds or transformer secondaries without cascading upstream — the SCCR is built into the frame, not an add-on. The breaker carries an undervoltage release (UVR) as standard, which drops the trip mechanism if the control voltage falls below the dropout threshold — a common requirement for safety disconnects on conveyor or pump lines where loss of control power must open the main contacts. A communication function is also built in, so it can report status or accept remote trip commands over a bus, though the protocol is not specified in this listing.
Thermal derating and real-world current
At 40 °C, 45 °C, and 50 °C the breaker holds its full 400 A rating. 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 hot — say, a sealed enclosure near a furnace line — the 70 °C figure is the one to size against, not the 40 °C nameplate.
Breaking capacity across voltage bands
The 3VA2340-5JQ42-0BC0 delivers 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. The steep drop at 690 V means it is not a primary choice for 690 V distribution unless the available fault current is well under 7.5 kA — verify the transformer impedance and cable length before committing the BOM line.
Physical fit and panel integration
Dimensions are 248 mm high, 184 mm wide, and 110 mm deep. The 184 mm width is the 4-pole frame — a 3-pole version of the same frame would be narrower, so a panel cutout or mounting plate designed for a 3-pole 3VA2 will not accept this unit without modification. The 110 mm depth includes the arc chamber and rear terminals; allow clearance for cable bending radius below the breaker.