Line protection MCCB — what the ratings mean for your panel
The Siemens 3VA1112-5EF36-0AE0 is a SENTRON 3-pole molded case circuit breaker rated for line protection duty, carrying a TM240 thermal-magnetic overcurrent release and 125 A of continuous current at 40 °C through 50 °C ambient. Breaking capacity is the headline: 187 kA at 240 V, 121 kA at 415 V, 75.6 kA at 440 V, and 17 kA at 690 V — that means this MCCB can safely interrupt fault currents up to those levels without welding contacts or cascading upstream, which is what you need for high-fault installations like transformer secondaries or large motor control centers. The TM240 release is a fixed thermal-magnetic trip unit — no electronic adjustment, no communication module, no ground-fault or undervoltage accessory fitted from the factory, but it does ship with four HQ auxiliary switches for remote status indication.
Continuous current derating — where the 125 A rating holds and where it tapers
Rated continuous current Iu is 125 A, and it holds flat from 40 °C through 50 °C ambient — no derating needed in a typical warm panel. Above 50 °C the TM240 release begins to taper: 120 A at 55 °C, 117.5 A at 60 °C, 115 A at 65 °C, 112.5 A at 70 °C. If your panel ambient runs hot — say near a furnace line or in a sealed cabinet — the 112.5 A floor at 70 °C still leaves headroom for a 100 A load.
Panel fit — footprint and integration
The 3VA1112-5EF36-0AE0 measures 130 mm high, 76.2 mm wide, and 70 mm deep — a standard SENTRON 3VA frame size that drops into a DIN-rail or screw-mounted panel without surprises. Front protection is IP40, so it's fine for a clean indoor panel but not for washdown or outdoor exposure without an additional enclosure. Operating temperature range is -25 °C to 70 °C; storage range is -40 °C to 80 °C — the storage limit governs handling and shipping, not running conditions.