Category strategy — SENTRON 3VA frame at 250 A
The Siemens 3VA1225-5EF32-0KB0 is a SENTRON molded case circuit breaker (MCCB) in a 3-pole configuration, rated 250 A continuous at 40 °C ambient. It is designed for line protection — the primary protective device in a distribution panel, not a motor-protective or ground-fault version. The 3VA platform is Siemens' current-generation MCCB family, consolidating the legacy 3VL series under a unified accessory and mounting footprint. Breaking capacity is the headline spec for this frame size: 187 kA at 240 V AC, 121 kA at 415 V, 75.6 kA at 440 V, 30 kA at 500 V, and 17 kA at 690 V. That 187 kA at 240 V puts it in the high-interrupting category — suitable for transformer-fed switchboards or large motor-control centers where fault current is high. The 690 V rating of 17 kA still covers most industrial distribution bus requirements. Thermal derating is published from 40 °C through 70 °C: the breaker holds full 250 A up to 50 °C, then steps down to 243 A at 55 °C, 237 A at 60 °C, 230 A at 65 °C, and 223 A at 70 °C. That curve lets you size the breaker for a panel's actual ambient without oversizing the frame. Rated insulation voltage is 800 V, covering 690 V systems with margin.
Lifecycle and supply base posture
Power loss at rated current is 57 W maximum — a figure to factor into panel thermal calculations, especially in densely populated switchboards. The breaker ships with a shunt trip (STL) release and two auxiliary switches HP as standard, per the design-of-auxiliary-switch and design-of-auxiliary-release fields. No undervoltage release is fitted; no communication function is integrated.
Integration — panel fit and mounting
Dimensions are 105 mm wide, 158 mm high, 70 mm deep. That 105 mm width is the standard 3VA 3-pole frame width — it occupies three 35 mm DIN-rail module positions if panel-mounted, or bolts directly onto a mounting plate via the rear fixing points. The 70 mm depth keeps the breaker within typical 200 mm deep enclosure profiles, leaving room for cable bending radii behind the line and load terminals. The breaker is designed for line protection, meaning the trip curve and accessories are optimized for cable and busbar protection rather than motor overload. If your BOM calls for motor protection, the 3VA family includes motor-protective variants with adjustable thermal-magnetic or electronic trip units — this specific order code is the fixed line-protection version. The supplied basic switch order code is 3VA12255EF320AA0, which is the internal switching mechanism; the external order code 3VA1225-5EF32-0KB0 is the complete assembled breaker.