What this MCCB is and what it does
The Siemens SENTRON 3VA2040-7KP36-0AA0 is a 3-pole molded case circuit breaker (MCCB) rated for 40 A continuous current, built around the ETU850 electronic trip unit. It's designed for line protection in distribution panels — the ETU850 gives you adjustable long-time, short-time, instantaneous, and ground-fault protection curves, plus a communication function for integration into a monitored power system. The 800 V rated insulation voltage and the breaking capacity profile — 330 kA at 240 V, 242 kA at 415/440 V, 187 kA at 500 V, and 3 kA at 690 V — tell you this breaker is built for high-fault-capacity main or feeder duty, not branch-circuit light loads. The IP40 front protection means it's fine in a clean indoor panel; no washdown rating here.
Sizing and thermal behaviour
The 40 A continuous rating holds flat from 40 °C through 70 °C ambient (–) — no derating needed across that range, which simplifies panel layout in warm enclosures. Maximum power loss is 1.2 W, negligible for heat budgeting. The adjustable trip range spans 60 A minimum to 480 A maximum, so the ETU850 can be set to coordinate with downstream breakers or protect a specific load profile. The 3-pole construction suits three-phase systems; the lack of an undervoltage release or voltage trip means external monitoring or shunt-trip accessories would need to be added if those functions are required.
Panel fit and dimensions
The breaker measures 105 mm wide, 181 mm high, and 86 mm deep. That 105 mm width is the standard 3-pole MCCB footprint for this SENTRON frame size — it occupies three 35 mm DIN-rail modules worth of panel width. The 86 mm depth (: 3.39 in) is shallow enough for most 200 mm deep enclosures, leaving room for wiring gutters and busbar connections. Mounting is via the rear DIN rail clip or screw-fixed base plate; the IP40 front means the breaker face is protected against tools and fingers but not against dripping water — keep it inside the enclosure.