What this MCCB does on a panel
The Siemens SENTRON 3VA2040-6KQ36-0AA0 is a 3-pole molded case circuit breaker (MCCB) rated for 40 A continuous current, designed for line protection in distribution panels. It carries a 242 kA interrupting capacity at 240 V, dropping to 187 kA at 415 V and 121 kA at 500 V — at 690 V it still holds 3 kA. That 242 kA figure means it can clear a bolted fault on a high-capacity transformer secondary without the arc flashing over to adjacent breakers; the 3-pole construction handles three-phase feeds common in industrial motor control centers and sub-distribution boards. Rated insulation voltage is 800 V, so it's suitable for 480/277 V and 600 V systems with margin. The breaker includes a communication function and ground-fault monitoring via summation current formation on the L-conductor — that's a built-in residual-current detection that sums the phase currents to find leakage to ground, saving an external RCD module in the panel.
Thermal derating and panel fit
The 40 A continuous rating holds flat from 40 °C through 70 °C ambient — no derating needed in a warm enclosure. That's unusual for an MCCB; most start pulling current back above 40 °C. The 2.2 W maximum power loss at rated load means it won't cook neighboring components in a densely packed panel. Dimensions are 181 mm high, 105 mm wide, 86 mm deep — standard SENTRON 3VA footprint, so it drops into existing 3VA busbar systems and mounting plates without re-drilling.