The Schneider Electric MGP1252L3N is a PowerPacT 4 molded case circuit breaker (MCCB) with a 1P+N pole configuration, rated 125 A at 40 °C for distribution applications.
This part is marked obsolete by the manufacturer. There is no listed official successor order code in the record. No direct drop-in replacement is documented here; a cross-reference search against the PowerPacT 4 family's active catalog numbers would be the next step for a new design.
Rated operational voltage is 230 V AC 50/60 Hz, so this is a single-phase (L3-N) breaker for 230 V line-to-neutral circuits. Rated insulation voltage of 750 V and impulse withstand of 8 kV give headroom for surge environments. The toggle control is manual on/off; no shunt trip or auxiliary switch is built in. Mounting is backplate (panel-mounted), horizontal or vertical orientation accepted.
Conforms to BS EN 60947-2, the UK/EU standard for low-voltage switchgear and controlgear — circuit-breakers. It is also suitability for isolation per that standard, so it can be used as a disconnecting means in a panel. The 20000 electrical cycles at rated current (277 V In/2) and 20000 mechanical cycles give a reasonable service life for a distribution breaker in a fixed installation.