MCCB for 250 A feeder protection
The Siemens SENTRON 3VA2225-6HN32-0AB0 is a 3-pole molded case circuit breaker rated for a continuous current Iu of 250 A, with an ETU350 electronic trip unit providing adjustable overload and short-circuit protection for line feeders. The interrupting capacity holds the unit on the grid at 242 kA at 240 V and 187 kA at 415 V — figures that give the site electrical engineer real selectivity headroom against upstream transformers and downstream panelboards, provided the coordination study respects the published let-through curves. The 800 V rated insulation voltage (Ui) means this breaker is comfortable in 480 V and 600 V class systems, though the interrupting rating at 690 V drops to 6 kA, so it's not the right choice for a 690 V main. The thermal derating is honest: full 250 A from 40 °C through 50 °C, then a steady decline to 213 A at 70 °C. If the panel ambient runs above 50 °C, the continuous load must be backed off accordingly — no guessing, the numbers are on the nameplate. Maximum power loss is 48 W, which matters for enclosure ventilation when several breakers are ganged. The auxiliary contact version carries 2 auxiliary switches HP, and the overcurrent release is the ETU350 — no undervoltage release, no ground-fault monitoring, no communication function, no phase-failure detection. This is a straightforward line-protection breaker, not a multifunction power-management device. The front face is rated IP40, so it's fine for a clean indoor panel but not for washdown environments.
Physical fit and panel integration
The breaker measures 105 mm wide, 181 mm high, and 86 mm deep — a standard 3-pole MCCB footprint that drops into a SENTRON 3VA mounting base or a fixed panel cutout. The 105 mm width is the same across the 3VA2 frame family, so if a panel was laid out for a 3VA2225-5HN42-0BB0, this unit will bolt in without rewiring, provided the lug kit and accessory positions match. No DIN-rail mounting on this frame size; it's screw-fixed to the backplate or mounting plate.