What this MCCB is and where it fits
The Siemens SENTRON 3VA1125-5EF32-0AB0 is a 3-pole molded case circuit breaker (MCCB) rated for line protection — the job it does is protecting cables and busbars from overloads and short circuits in a distribution panel. It carries a rated continuous current (Iu) of 25 A at 40 °C, and it's built around a TM240 thermal-magnetic release, so the thermal element handles sustained overloads while the magnetic element clears hard faults fast.
What the interrupting ratings mean for your panel
This breaker's interrupting capacity at 240 V is 187 kA — that's the maximum fault current it can safely interrupt at that voltage without welding contacts or rupturing the case. At 415 V it's still 121 kA, at 440 V it's 75.6 kA, and at 690 V it drops to 17 kA. What that tells you: on a 240 V or 415 V distribution board with high available fault current (say, close to a large transformer), this MCCB gives you the headroom to avoid cascading failures upstream. The rated insulation voltage is 800 V, so the internal clearances are designed for 690 V systems as well.
Thermal derating — the real-world current you can expect
At 40 °C, 45 °C, and 50 °C the breaker holds a full 25 A without derating. At 55 °C it drops to 24 A, at 60 °C to 23.5 A, at 65 °C to 23 A, and at 70 °C to 22.5 A. If your panel runs hot — say, a crowded enclosure near a furnace line — you need to account for that 2.5 A loss at the top end. The operating temperature range is -25 °C to 70 °C, so it's fine for most indoor industrial environments.
Auxiliary contacts and mounting
This version comes with 2 auxiliary switches HP (high-performance) pre-fitted — they signal the breaker's open/closed and tripped status back to a PLC or indicator lamp without needing a separate aux block. The front face is IP40, so it's splash-protected from the front but not sealed against hose-down. Depth is 70 mm, width 76.2 mm, height 130 mm — it fits the standard SENTRON 3VA panel footprint, so it swaps into an existing 3VA cutout without re-drilling the mounting plate.