What it is and what it does
The Siemens 3VA1140-6EF36-0HC0 is a SENTRON molded case circuit breaker (MCCB) rated for line protection, with a continuous current Iu of 40 A and a TM240 thermal-magnetic overcurrent release. It carries 220 kA interrupting capacity at 240 V, 154 kA at 415 V, 121 kA at 440 V, and 17 kA at 690 V — those numbers tell you it handles high-fault-current industrial feeds, not just branch circuits. The 3-pole design with 2 auxiliary switches (HQ version) and an integrated shunt trip (STL) means it can be remotely tripped via a separate control signal, which is useful for emergency-stop or interlock circuits in a panel.
Ratings and what they mean for fit
The 40 A rating holds flat from 40 °C up to 50 °C — no derating needed in a warm enclosure. At 55 °C it drops to 38.4 A, at 60 °C to 37.6 A, at 65 °C to 36.8 A, and at 70 °C to 36 A. If your panel ambient sits at 50 °C or below, you get full 40 A continuous. The rated insulation voltage Ui is 800 V, so it's fine on 480 V and 600 V class systems. The TM240 release is a fixed thermal-magnetic type — no interchangeable trip units, so what you order is what you get. The 15 000 mechanical endurance cycles (latching) tell you it's built for a moderate number of operations, not a switching duty cycle like a contactor.
Mounting and integration
Dimensions are 130 mm high, 76.2 mm wide, 70 mm deep. It mounts on a DIN rail or can be screw-fixed to a backplate — the 76.2 mm width is a standard 3-pole MCCB footprint, so it fits existing cutouts and busbar layouts. The front face carries IP40 protection, meaning tools or fingers won't reach live parts, but it's not sealed against water ingress — keep it inside the enclosure. The shunt trip release (STL) is wired separately; the auxiliary contacts (2 HQ switches) give status feedback to a PLC or indicator lamp. No communication module, no ground-fault monitoring, no undervoltage release on this variant — it's a straightforward thermal-magnetic breaker with remote trip capability.