What this MCCB is and what it does
The Siemens 3VA1125-5GE46-0AA0 is a SENTRON molded case circuit breaker (MCCB) rated for line protection — it's the primary overcurrent and short-circuit safeguard in a distribution panel, not a motor-starter combination. Four poles, 25 A continuous, with a TM220 thermal-magnetic release that handles both overload (thermal) and instantaneous fault (magnetic) trips. The 187 kA breaking capacity at 240 V is the headline number, but what matters for panel coordination is the full voltage curve: 121 kA at 415 V, 75.6 kA at 440 V, and 17 kA at 500 V and 690 V. That tells you this breaker is sized for high-fault installations where the available short-circuit current is substantial — think industrial switchgear, not a light-commercial load center.
Thermal derating and real-world current
The 25 A rating holds flat from 40 °C to 50 °C ambient — no derating needed in a typical ventilated enclosure. At 55 °C it drops to 24 A, at 65 °C to 23 A, and holds 23 A through 70 °C. If your panel runs hot (stacked breakers, poor airflow), factor that 2 A loss above 50 °C. The TM220 release is fixed-trip, not adjustable, so the thermal curve is set at the factory.
Physical fit and panel integration
Dimensions: 101.6 mm wide (4 in), 130 mm tall (5.12 in), 70 mm deep (2.76 in). IP40 on the front face. The 4-pole format switches three phases and neutral.
Power loss and auxiliary considerations
Maximum power dissipation is 8.5 W at rated load. No undervoltage release, no trip indicator, no communication function on this variant. Insulation voltage rated 800 V.