Line protection MCCB with ETU560 — 25 A, 187 kA at 240 V
The Siemens 3VA2125-5JQ46-0CJ0 is a SENTRON molded case circuit breaker (MCCB) configured for line protection, with a rated continuous current Iu of 25 A and a 4-pole frame. Its interrupting capacity hits 187 kA at 240 V and 121 kA at 415 V — figures that place it in the high-fault category for industrial distribution panels where upstream transformer capacity or motor contribution drives available fault current above typical MCCB ratings. At 690 V the rating drops to 3.75 kA, so verify the system voltage before specifying. The ETU560 electronic trip unit supports adjustable protection curves and communication, making this breaker suitable for selective coordination studies and power-monitoring schemes. The undervoltage release is integrated — it will trip on loss of control voltage, a common requirement for emergency-stop circuits and safety disconnects in conveyor or pump panels.
Thermal derating and panel fit
The breaker carries its full 25 A continuously up to 50 °C ambient. Above that it derates linearly: 24.06 A at 55 °C, 23.13 A at 60 °C, 22.19 A at 65 °C, and 21.25 A at 70 °C (–). In a sealed enclosure or next to heat-generating drives, that 70 °C ceiling is the real limit — not the 25 A label. The 140 mm width and 107 mm depth fit a standard 4-pole MCCB footprint; the IP40 front means the face is protected against tools and wires >1 mm but not against moisture, so mount it in a dry, lockable section of the panel.