What it is and what it does
The Siemens SENTRON 3VA2440-5MN32-0AD0 is a 3-pole molded case circuit breaker (MCCB) rated for 400 A continuous current across the full ambient range from 40 °C to 70 °C — no derating needed up to that ceiling. It is specifically designed for motor protection, with built-in phase failure detection that trips the breaker when one phase drops out — a common cause of single-phasing damage on three-phase motor loads. The interrupting ratings are 187 kA at 240 V, 121 kA at 415 V and 440 V, 75.6 kA at 500 V, and 9 kA at 690 V — the 415 V figure is the one most panel builders will reference for a 400 V class distribution system. Maximum power loss is 63.5 W, which matters for enclosure thermal calculations when grouping several breakers in a confined panel.
Panel fit and integration
Dimensions are 248 mm high, 138 mm wide, 110 mm deep — the 138 mm width is the standard 3-pole MCCB footprint for this class, so it drops into existing SENTRON mounting bases or DIN-rail adapters without panel rework. The breaker ships with three HQ auxiliary switches integrated (design of the auxiliary switch: 3 auxiliary switches HQ), and the basic switch variant is 3VA2440-5MN32-0AA0 — the -0AD0 suffix adds the auxiliary switch configuration. Operating temperature range is -25 °C to 70 °C; storage range is -40 °C to 80 °C — the storage minimum matters if the breaker sits in an unheated warehouse before installation.
What the ratings mean for your BOM line
The 400 A rating at 70 °C means this breaker handles full motor FLA without a temperature derate in a warm enclosure — many MCCBs start derating above 40 °C, so this is a genuine advantage for tightly packed panels. Phase failure detection is an integrated function, not an add-on module — if you are specifying motor protection, this saves an auxiliary relay and a wiring step. The 121 kA SCCR at 415 V gives headroom for high-fault installations downstream of a large transformer; the 9 kA at 690 V is the ceiling for 690 V systems where fault current is typically lower.