What this MCCB is and what it does
The Siemens 3VA1140-5MH36-0AA0 is a SENTRON 3VA1 molded case circuit breaker (MCCB) built for starter protection — meaning it's designed to sit ahead of a motor contactor and handle the high inrush without nuisance tripping, while still clearing a bolted fault. Rated 40 A continuous at 40 °C (derates to 37 A at 70 °C), it's a 3-pole unit with a TM120M thermal-magnetic release that tracks the motor's heating curve. The interrupting rating is the headline: 187 kA at 240 V, 121 kA at 415 V, and still 7.5 kA at 690 V — that's enough to ride through a fault on a high-capacity transformer secondary without the breaker itself becoming the weak link.
Ratings that decide the fit
The 187 kA interrupting rating at 240 V is the number that matters for high-fault panels — it means this breaker can safely interrupt a fault current up to that level without rupturing or welding contacts, which is critical for UL 489 listed series ratings where the MCCB is the main device. At 415 V it still clears 121 kA, so it handles most industrial distribution bus faults. The 40 A frame with TM120M release is sized for motor branch circuits up to about 25 hp at 460 V; the thermal element tracks the motor's locked-rotor profile, so you don't get nuisance trips on start. The 70 mm depth and 76.2 mm width fit the standard SENTRON 3VA panel footprint — same cutout as the rest of the 3VA1 family, so a panel laid out for a 63 A frame accepts this 40 A unit without re-drilling.
Where it goes in the panel
Mounts on a DIN rail or direct-panel mount via the 3VA1 base. The 3-pole design means it occupies three module widths (76.2 mm total). Front IP40 protection keeps dust out of the enclosure; the breaker itself is rated for use in a standard industrial panel with no additional sealing. The TM120M release has a fixed thermal and magnetic setting — no adjustment dial, so the trip curve is set at the factory for the 40 A rating. No undervoltage release, no shunt trip, no communication module on this variant — it's a straight electromechanical MCCB with no auxiliary electronics.