What this MCCB is and what it does
The Siemens 3VA1125-5EF36-0AG0 is a SENTRON 3VA molded case circuit breaker (MCCB) rated for 25 A continuous current at 40 °C, 3-pole, configured for line protection with a TM240 thermal-magnetic release. It carries a 187 kA interrupting capacity at 240 V, 121 kA at 415 V, and 75.6 kA at 440 V — numbers that tell you this breaker handles high-fault-current scenarios typical in distribution panels feeding motor control centers or transformer secondaries. The 25 A rating holds flat from 40 °C through 50 °C, then derates to 24 A at 55 °C and 22.5 A at 70 °C — a thermal curve worth checking if your panel ambient runs hot. The TM240 release means the thermal element is fixed at 25 A; no field-adjustable overload pickup on this variant.
Integration and mounting
Mounts on a DIN rail or panel-mount baseplate; the 76.2 mm width (3-pole standard) and 70 mm depth fit standard 3VA cubicle cutouts. IP40 on the front face — sufficient for enclosed distribution boards, not for washdown environments. The built-in trip indicator (red/green flag) gives a quick visual on tripped status without opening the door.
Auxiliary contacts and ratings
Comes with one auxiliary switch and one trip alarm switch (HP type) factory-installed. No undervoltage release, no shunt trip, no communication module — this is a basic line-protection breaker. The 800 V rated insulation voltage (Ui) covers 480/600 V distribution systems with margin. Latching endurance rated at 15,000 operations, which is typical for this class of fixed thermal-magnetic MCCB.