What it is and what it does
The Siemens 3VA2340-5HN32-0HC0 is a SENTRON molded case circuit breaker (MCCB) rated for line protection in distribution panels. It carries 400 A continuous current at 40 °C through three poles, and its interrupting capacity hits 187 kA at 240 V, 121 kA at 415 V, and 7.5 kA at 690 V — so it handles high-fault utility feeds and transformer secondaries without cascading upstream. Built into a 248 mm high by 138 mm wide by 110 mm deep frame, it fits standard switchboard or panelboard mounting footprints. The unit ships with a shunt trip (STL) for remote emergency-off circuits and two auxiliary switches HQ for status feedback to a PLC or annunciator.
Current derating and thermal limits
The breaker holds its full 400 A rating up to 50 °C ambient. Above that, it derates linearly: 385 A at 55 °C, 370 A at 60 °C, 355 A at 65 °C, and 340 A at 70 °C. If your panel runs hot — say, tightly packed with other breakers or near a transformer — size the load side for the derated figure, not the nameplate 400 A. Maximum power loss at rated current is 96 W. That's the heat the breaker dumps into the enclosure; factor it into your thermal budget if the panel is sealed or has limited ventilation.
What the interrupting ratings mean for your panel
The 187 kA at 240 V and 121 kA at 415 V tell you this MCCB can interrupt fault currents at those levels without welding contacts or rupturing the case. That's typical for a high-capacity feeder breaker in a large industrial plant or a utility service entrance. At 690 V the interrupting capacity drops to 7.5 kA — still adequate for most 690 V motor circuits, but verify your available fault current before specifying.
Integration and wiring
Three-pole design with line-side and load-side lugs for copper or aluminum conductors. The shunt trip release (STL) is wired to a remote E-stop or safety relay circuit; the two auxiliary switches HQ provide normally-open/normally-closed contacts for status monitoring. No undervoltage release or ground-fault module on this variant — if you need those, look at the 3VA2 family options with UVR or GF add-ons.