What this 4-pole MCB does on the line
The four poles (4P) switch all phases in a single module width of 4 modular units (72 mm wide), so it fits standard DIN-rail enclosures without extra bridging.
Thermal derating and environment
Rated 3 A at 35 °C ambient, the breaker derates to 2.82 A at 40 °C, 2.73 A at 45 °C, 2.63 A at 50 °C, and 2.53 A at 55 °C. If the panel runs warm — common in a crowded enclosure or near a freezer evaporator — size the load against the derated value at the actual ambient.
Depth is 76 mm, installation depth 70 mm, width 72 mm (4 MW), height 90 mm. The neutral is not switched (no neutral pole), so this breaker protects three phases plus a switched neutral? Check: the 4P designation here means all four poles are protected poles — verify the datasheet if you need a switched neutral.