The Siemens 3VA2340-5JQ42-0CL0 is a 4-pole SENTRON molded case circuit breaker rated for 400 A continuous at 40 °C — line protection version with an ETU560 electronic trip unit. Breaking capacity hits 187 kA at 240 V, 121 kA at 415 V, and still holds 17 kA at 690 V, so it handles high-fault utility feeds or transformer secondaries without cascading upstream. The 184 mm width and 248 mm height fit standard SENTRON panel cutouts; depth is 110 mm.
What the ratings mean for fit
The 400 A continuous rating holds flat from 40 °C to 50 °C — no derating needed in a warm panel. At 55 °C it drops to 375 A, at 60 °C to 350 A, at 65 °C to 325 A, and at 70 °C to 300 A. If your enclosure ambient runs above 50 °C, size the breaker for the derated current, not the nameplate 400 A. The 187 kA at 240 V is the peak interrupting rating — it safely clears a fault that high without welding contacts or venting gas into adjacent gear. At 690 V the rating drops to 17 kA, still adequate for most 690 V distribution but verify against your available fault current. Rated insulation voltage is 800 V, so it's suitable for 690 V systems with margin. The ETU560 electronic trip provides adjustable long-time, short-time, instantaneous, and ground-fault protection — configurable for selective coordination downstream.
Integration notes
The breaker ships with a factory-installed undervoltage release (UVR) and a communication module — the UVR trips the breaker on loss of control voltage, which is common in safety circuits or remote emergency-stop chains. The auxiliary contact block includes 2 auxiliary switches plus 1 trip alarm and 1 electrical alarm switch (HQ type), giving status feedback to a PLC or annunciator panel. Ground-fault monitoring uses summation-current formation on L + N — it measures the vector sum of phase and neutral currents to detect leakage. No phase-failure detection built in; if you need that, it's handled by the ETU or an external relay. Maximum power loss is 98.5 W — account for that heat in the enclosure thermal calculation, especially if the panel is tightly packed. Latching endurance is 15,000 operations, which is typical for a distribution breaker not cycled daily.