What it is and where it goes
The Siemens 3VA2140-5MN32-0HH0 is a SENTRON molded case circuit breaker (MCCB) designed specifically for motor protection. Rated 40 A continuous across the full -25°C to +70°C operating range, it handles motor loads without derating as panel temperatures rise — that means one part number for the whole enclosure, no temperature zone calculations. Phase failure detection is built in, so a lost leg trips the breaker before single-phasing cooks the motor winding. Interrupting capacity sits at 121 kA at 415 V and 187 kA at 240 V — high enough for most transformer-fed industrial services without a current-limiting fuse upstream. At 690 V the rating drops to 3.7 kA, so if the line side is 690 V, verify the available fault current stays below that threshold.
Lifecycle and sourcing posture
The basic switch inside is order code 3VA21405MN320AA0, which is the interchangeable thermal-magnetic trip unit. If a panel already carries a 3VA frame, the trip unit swaps independently of the case.
Fit and wiring details
Mounts on a DIN rail — 105 mm wide, 181 mm tall, 86 mm deep. The depth leaves clearance behind a standard gland plate. Built-in auxiliary switch configuration: two auxiliary switches plus one trip alarm switch. The auxiliary release is a shunt trip (STL) — that's a separate coil that trips the breaker on command from an emergency-stop circuit or a remote relay. No undervoltage release on this variant. Power loss at rated load is 1.6 W maximum — negligible for panel thermal budgeting.
Coordination and selectivity note
The 121 kA at 415 V and 75.6 kA at 500 V give this MCCB enough interrupting capacity to serve as a main breaker in most 400 V distribution boards fed by a 1 MVA or smaller transformer. Selectivity with downstream 10–25 A miniature breakers is achievable with the right time-current curve — the trip indicator and voltage trigger aid in troubleshooting. Storage range is -40°C to +80°C, wider than the operating range, which matters if the spare sits on a cold warehouse shelf.