What this MCCB is and what it does
The Siemens 3VA2225-5JQ32-0AJ0 is a SENTRON 3VA2 molded case circuit breaker (MCCB) designed for line protection in distribution panels. It is a 3-pole unit rated 250 A at 40 °C, with a full-scale value of 250 A and an initial setting of 50 A. The breaker carries a maximum breaking capacity of 187 kA at 240 V, 121 kA at 415 V, and 4.5 kA at 690 V — the 690 V figure is the tail-off point that governs its use on 690 V systems where fault current is low.
Ratings that decide fit
The headline rating is 250 A continuous at 40 °C, but the breaker is thermally rated across a range: it holds 250 A up to 50 °C, then derates to 238 A at 55 °C, 225 A at 60 °C, 213 A at 65 °C, and 200 A at 70 °C. If your panel ambient runs above 50 °C, the effective ampacity is lower than the nameplate — size accordingly. The interrupting ratings span the common industrial voltages: 187 kA at 240 V, 121 kA at both 415 V and 440 V, 75.6 kA at 500 V, and 4.5 kA at 690 V. The 121 kA at 415 V is the figure most relevant for European 400 V distribution — it gives headroom for high-fault installations without cascading upstream. Maximum power loss is 48 W, which matters for enclosure thermal calculations when multiple breakers are ganged in a panel.
Integration and wiring
The breaker measures 105 mm wide, 181 mm high, and 86 mm deep. It mounts in a standard distribution panel footprint — the 105 mm width is a 3-pole MCCB form factor that fits Siemens SENTRON busbar systems and panelboards. It includes a trip indicator and a communication function. The auxiliary switch configuration is 2 auxiliary switches plus 1 trip alarm switch (HP type). There is no undervoltage release and no auxiliary release.