Siemens SENTRON 3VA2140-5MN36-0AB0 — 40 A MCCB for Motor Protection
The Siemens 3VA2140-5MN36-0AB0 is a 3-pole molded case circuit breaker from the SENTRON family, designed specifically for motor protection. It carries a continuous current rating of 40 A across the full ambient temperature range from 40 °C to 70 °C, meaning no derating is needed in a warm panel — a practical advantage when the breaker sits near other heat-generating devices. The 187 kA interrupting capacity at 240 V and 121 kA at 415 V give it the headroom to clear high-fault conditions without cascading upstream, which simplifies coordination studies in a distribution board.
Motor Protection and Phase Failure Detection
This MCCB is built for motor protection duty, with integrated phase failure detection. That means it will trip if one phase drops out — a common failure mode that can single-phase a motor and burn it out if the overload relay doesn't catch it fast enough. The design eliminates the need for a separate phase-failure relay in the motor branch circuit, saving a DIN-rail slot and a wiring step. The basic switch is order code 3VA21405MN360AA0, and the auxiliary switch configuration is two HP-style aux switches, which can be wired for remote status indication or interlocking.
Breaking Capacity and Selectivity
The interrupting ratings are given at five voltage levels: 187 kA at 240 V, 121 kA at 415 V and 440 V, 75.6 kA at 500 V, and 3.7 kA at 690 V (–). The sharp drop at 690 V is typical for a 40 A frame — the arc energy at that voltage exceeds what the compact arc chutes can extinguish at high current. For a 400 V distribution system, the 121 kA rating covers most industrial transformer sizes up to about 2.5 MVA. The minimum trip time is 4 s, maximum 17 s, which is a thermal-magnetic or electronic trip curve suited for motor starting inrush without nuisance tripping.
Physical Fit and Panel Integration
Dimensions are 105 mm wide, 181 mm high, and 86 mm deep (–). That is a standard SENTRON 3VA2 frame size — it mounts on a DIN rail or can be screw-mounted to a backplate. The 86 mm depth means it will clear a standard 200 mm deep enclosure with room for wiring gutters. No undervoltage release, no voltage trip, no communication module, and no ground-fault monitoring are built in; if those functions are needed, they must be added via external accessories or a different variant.