What this MCCB carries — and what that means on the panel
The Siemens 3VA2225-6HN32-0AJ0 is a SENTRON molded case circuit breaker sized for 250 A continuous duty, with an electronic ETU350 overcurrent release that gives you adjustable long-time, short-time, and instantaneous pickup — not a fixed thermal-magnetic, so you can coordinate selectivity downstream without swapping the breaker. Rated insulation voltage is 800 V, and the interrupting ratings climb to 242 kA at 240 V and 187 kA at 415 V — numbers that tell you this breaker is built for high-fault panels, not light distribution. Three poles, line-protection version, no undervoltage release, no ground-fault module, no communication stack — it's a straight feeder or main breaker, not a multifunction device.
Thermal derating and real-world loading
At 40 °C the breaker holds the full 250 A without derating; at 55 °C it's 241 A, at 70 °C it's 213 A. That means in a warm panel — say 50 °C — you still get the full 250 A, but if the enclosure runs hot from adjacent drives or transformers, you lose about 15 % by 70 °C. Plan your ambient accordingly. Maximum power loss is 48 W at rated current — not trivial in a sealed enclosure. If you're packing several breakers in a row, factor that heat into the panel ventilation or the internal temperature rise will push you down the derating curve faster than the ambient alone suggests.
Footprint and mounting
Dimensions are 105 mm wide, 181 mm tall, 86 mm deep — a standard 3-pole MCCB footprint that drops into most SENTRON panelboards and distribution blocks without re-drilling the mounting plate. Front face carries IP40 protection — fine inside a cabinet, not for outdoor or washdown exposure.
Auxiliary contact configuration
Comes fitted with 2 auxiliary switches plus 1 trip-alarm switch (HP type) — enough to signal breaker position and fault status back to a PLC or annunciator without adding an external contact block.