1-pole MCCB for line protection — 20 A, TM210 release, 53 kA at 240 V
The Siemens SENTRON 3VM1120-3ED12-0AA0 is a 1-pole molded case circuit breaker (MCCB) designed for line protection in distribution panels. It carries a continuous current rating of 20 A at 40 °C ambient, with the TM210 thermal-magnetic release providing both overload and short-circuit protection in a single unit. The interrupting capacity is 53 kA at 240 V AC and 8 kA at 415 V AC — the 415 V figure is the one that governs most European 400 V distribution, so verify your available fault current against that lower value, not the 240 V headline. The 1-pole form factor (25.4 mm wide) fits a single module on a DIN rail, leaving adjacent slots for other breakers or accessories. Rated insulation voltage is 500 V, and the operating voltage is 415 V AC or 125 V DC. The TM210 release is fixed — no interchangeable trip units — so the 20 A rating is baked in at the factory. Maximum power loss is 4 W.
Thermal derating and ambient limits
The 20 A rating holds flat from 40 °C through 55 °C. At 60 °C it derates to 19 A, and stays at 19 A through 70 °C. That means in a warm panel — say 50 °C internal ambient — you still get the full 20 A; no need to oversize for a typical industrial enclosure. The operating ambient range is -25 °C to 70 °C, storage -40 °C to 80 °C.
Panel fit and integration
The 3VM1120-3ED12-0AA0 mounts on a standard DIN rail. Depth is 70 mm, height 130 mm, width 25.4 mm — a single 1-pole module. The front face carries IP40 protection, adequate for enclosed distribution boards. No undervoltage release, no trip indicator, no communication function — this is a basic thermal-magnetic MCCB for straightforward line protection duty.