What this 4-pole 0.3 A MCB is for
It is designed for branch-circuit protection in control panels, distribution boards, and industrial machinery where the load draws under a third of an amp — think signal transformers, contactor coils, or small power supplies. Rated breaking capacity is 70 kA per IEC 60947-2 at AC, and 15 kA at DC per the same standard.
Pollution degree 3, overvoltage category III — rated for fixed installations in industrial environments where conductive pollution may occur. Ambient temperature range is -40 °C to 75 °C, with derating above 55 °C: at 55 °C the rated current drops to 0.28 A, at 70 °C to 0.29 A (the spec table shows a slight non-monotonicity, but the trend is clear — above 55 °C, derate). Vibration resistance per IEC 60068-2-6: ±1 mm at 5–25 Hz, 50 m/s² at 25–150 Hz.