What it is and what it does
The Siemens 3VA2140-8HM36-0AA0 is a SENTRON molded case circuit breaker (MCCB) designed for line protection — the primary job is guarding feeders and distribution branches against overloads and short circuits. It's a 3-pole unit rated at 40 A continuous current, with an insulation voltage of 800 V, meaning it's sized for standard 400 V industrial panels but carries headroom for higher-voltage distribution. The 40 A rating holds flat across the full operating temperature range from -25 °C to 70 °C (, -), so no derating curve to chase in a warm enclosure. Breaking capacity is what decides whether this breaker clears a fault without welding its contacts or venting plasma. At 240 V it interrupts 440 kA; at 415 V and 440 V it's 330 kA; at 500 V it's 220 kA; and at 690 V it's 52.5 kA. Those numbers are high enough for most industrial service-entrance and sub-distribution panels — the 440 kA at 240 V covers high-fault locations like transformer secondaries. The breaker also includes summation-current ground-fault monitoring, which sums the phase conductors to detect leakage without a separate GFCI module.
Panel fit and mounting
The 3VA2140-8HM36-0AA0 measures 86 mm deep by 105 mm wide by 181 mm tall. It's a DIN-rail-mount MCCB — snaps onto standard 35 mm rail, so it goes into a panel the same way a contactor or terminal block does. The 105 mm width for a 3-pole 40 A breaker is compact for its class; it leaves room alongside for other SENTRON or SIRIUS components on the same rail. Power loss is only 1.2 W maximum, so heat buildup in a dense enclosure is minimal.