Siemens SENTRON 3VM1225-4ED32-0AA0 — 250 A MCCB, TM210 Release
The Siemens SENTRON 3VM1225-4ED32-0AA0 is a 3-pole molded case circuit breaker (MCCB) rated 250 A at 40 °C, designed for line protection in distribution panels. Its TM210 thermal-magnetic overcurrent release handles overload and short-circuit protection without a separate trip unit. The interrupting ratings are what decide fit: 121 kA at 240 V, 76 kA at 415 V, 53 kA at 440 V, and 17 kA at 500 V — so at 415 V it clears faults up to 76 kA without cascading upstream, which is the figure most panel builders check for IEC 60947-2 coordination. The 70 mm depth and 105 mm width fit standard MCCB panel mounting footprints.
Thermal Derating and Continuous Current
The breaker holds 250 A continuous from 40 °C through 50 °C ambient. Above that it derates linearly: 243.3 A at 55 °C, 236.5 A at 60 °C, 229.8 A at 65 °C, and 223 A at 70 °C. If the panel ambient hits 60 °C, the available continuous current drops to 236.5 A — the so-what is that a 250 A feeder needs a panel ventilation review or a higher-frame breaker if the enclosure runs hot. Maximum power loss at rated current is 57 W, which feeds into the enclosure thermal calculation.
Physical Integration and Approvals
Front-side protection class is IP40 — suitable for enclosed panel mounting, not for washdown or outdoor exposure. Rated insulation voltage is 800 V, so it can be applied in 690 V systems with margin. The TM210 release design means the thermal and magnetic settings are factory-fixed; no field-adjustable dials. No undervoltage release, no ground-fault monitoring, no communication function — this is a plain line-protection MCCB. Operating temperature range is -25 °C to 70 °C; storage from -40 °C to 80 °C.