What this MCCB is and what it protects
The Siemens 3VA2125-6HN46-0AA0 is a SENTRON molded case circuit breaker (MCCB) designed for line protection — meaning it sits at the feeder or main distribution point, not on a motor branch. It carries a continuous current rating of 25 A (flat across the full 40–70 °C ambient range, so no derating headache in a warm enclosure) and an insulation voltage of 800 V, which covers most 400/480 V industrial panels with headroom for 690 V systems. The ETU350 electronic trip unit gives you adjustable long-time, short-time, instantaneous, and ground-fault protection curves — not a fixed thermal-magnetic, so you can coordinate selectively with downstream breakers.
Interrupting capacity — the real number for fault duty
At 240 V this breaker clears 242 kA symmetrical — that's a very high interrupting rating, typical for a large-frame MCCB on a high-fault utility feed. At 415/440 V it still holds 187 kA, and at 500 V it's 121 kA. The drop to 3.7 kA at 690 V tells you this is a 240–500 V part for most practical installations; if your system is 690 V, the available fault current must be under 3.7 kA, which is a niche case. The 4-pole construction means it switches all three phases plus neutral, common for TN-S or TN-C-S systems where the neutral needs protection.
Mounting and panel fit
Dimensions are 181 mm high, 140 mm wide, 86 mm deep — a standard 4-pole MCCB footprint for 160 A frame size. It mounts on a DIN rail or directly to a backplate via the screw terminals. The front face carries IP40 protection, so it's fine inside a closed panel; no washdown rating, so keep it out of wet zones. Power loss at rated current is only 0.6 W, negligible for thermal budgeting inside a crowded cabinet.