What this MCCB is and what it does
The Siemens 3VA1125-5EF32-0AH0 is a SENTRON molded case circuit breaker (MCCB) designed for line protection in distribution panels. It carries a 25 A continuous rating at 40 °C, with a TM240 thermal-magnetic overcurrent release that provides both overload and short-circuit protection. The 3-pole construction suits three-phase feeders or branch circuits. Its interrupting capacity reaches 187 kA at 240 V AC, dropping to 121 kA at 415 V and 75.6 kA at 440 V — figures that cover most industrial service-entrance and distribution applications where high fault current is a concern. At 500 V and 690 V the rating settles to 17 kA, so verify the available fault current at the point of installation.
Thermal derating and ambient limits
The breaker holds its full 25 A rating from 40 °C up to 50 °C. At 55 °C it derates to 24 A, and at 70 °C to 23 A. Operating ambient range is -25 °C to 70 °C; storage range is -40 °C to 80 °C. For cold-chain or freezer applications, the -25 °C operating floor means it runs cold and stays cold — no condensation issues at sub-zero panel temperatures.
Physical fit and panel integration
The 3VA1125-5EF32-0AH0 measures 70 mm deep, 76.2 mm wide, and 130 mm tall. The 76.2 mm width (3 inches) is the standard 3-pole MCCB footprint for Siemens SENTRON 3VA breakers — it drops into a panel designed for that family without re-drilling the mounting plate. Power loss at rated current is 8.5 W max, which matters for enclosure heat-rise calculations.
Auxiliary switching and signaling
This variant includes 2 auxiliary switches plus 1 trip alarm switch (HQ type). The trip alarm signals a faulted state independently of the auxiliary contacts — useful for remote annunciation in a PLC or SCADA system. No undervoltage release or ground-fault monitoring is fitted on this order code.