MCCB for line protection — 25 A, 4-pole, TM210 release
The Siemens SENTRON 3VA1125-4GD42-0AA0 is a 4-pole molded case circuit breaker (MCCB) rated for 25 A continuous current, designed for line protection in distribution panels and motor control centers. The TM210 thermal-magnetic release provides fixed overload and short-circuit protection — no adjustment dials, which means the trip curve is locked at the factory and cannot be inadvertently changed during commissioning or maintenance. This is relevant under GMP change-control expectations: the protection settings are qualifiable and traceable because they are not field-adjustable. Breaking capacity is 121 kA at 240 V AC, derating to 75.6 kA at 415 V and 52.5 kA at 440 V. At 500 V and 690 V it holds 11.9 kA. These figures govern selectivity coordination with downstream devices — the site electrical engineer should verify that the fault current at the point of installation does not exceed the rated breaking capacity at the system voltage.
Current-carrying capacity across ambient temperature
The breaker carries its full 25 A rating from 40 °C to 50 °C ambient. At 55 °C it derates to 24 A, at 65 °C to 23 A, and holds 23 A through 70 °C. When panel internal temperature exceeds 50 °C — common in sealed enclosures with multiple heat sources — the load current must be reduced accordingly. The maximum power loss is 8.5 W per pole, which contributes to the enclosure thermal budget.
Physical fit and mounting
Dimensions are 70 mm deep, 101.6 mm wide, and 130 mm high — a 4-pole MCCB footprint that fits standard Siemens SENTRON mounting bases. The front face carries IP40 protection, suitable for installation inside a panel where the enclosure provides the environmental seal. No undervoltage release or communication module is fitted; this is a standalone breaker for basic line protection.