This is a Siemens SENTRON 3VA1050-3ED42-0AH0 molded case circuit breaker — 4-pole, 50 A continuous at 40 °C, with a TM210 thermal-magnetic release tuned for line protection. The interrupting ratings climb to 75.6 kA at 240 V and still hold 52.5 kA at 415 V, so it handles high-fault utility feeds without cascading upstream. At 440 V it breaks 32 kA; at 500 V and 690 V it still clears 7.5 kA — enough for most industrial secondary distribution. Rated insulation voltage is 800 V, and the thermal derating curve is flat to 50 °C — still 50 A — then drops to 49 A at 55 °C, 48 A at 60 °C, 46 A at 65 °C, and 45 A at 70 °C. That means in a warm panel you lose only 5 A at the top end; the breaker doesn't force a big oversize just because ambient hits 60 °C.
Maximum power loss is 14.6 W, which is modest for a 4-pole 50 A frame — helps keep panel internal temperature rise manageable when grouped with other breakers.
Mechanical fit and panel integration
Dimensions: 130 mm height, 101.6 mm width, 70 mm depth. That covers unheated warehouses and outdoor-rated enclosures in most climates.