What this MCCB carries — and what it doesn't
The Siemens SENTRON 3VM1120-4EE42-0AA0 is a 4-pole molded case circuit breaker (MCCB) rated for 20 A continuous current with a TM220 thermal-magnetic release. It's a line-protection device, not a motor-protective breaker — no ground-fault monitoring, no N-conductor protection, no communication module, and no motor-drive option on the accessory slot. That means it lives in a distribution panel or sub-feed, not on a motor starter bucket. Breaking capacity is the headline: 121 kA at 240 V AC, 76 kA at 415 V, 53 kA at 440 V, and 11.9 kA at 500 V. Those numbers cover the high-fault end of commercial and light-industrial distribution — think transformer secondaries or busway taps where the available fault current is stiff. The 500 V figure drops to 11.9 kA, so if you're on a 480 V corner-grounded delta or a 500 V DC system (max rated operational voltage Ue with DC is 500 V), verify the SCCR of the downstream panel matches. The TM220 release is fixed at 20 A (Ir max. adjustable to 20 A). Rated insulation voltage Ui is 690 V.
Panel fit — DIN rail or direct mount
Dimensions: 101.6 mm wide, 130 mm tall, 70 mm deep. Front face IP40 rated. Power loss is 12 W maximum at full load.
Temperature derating — flat to 55 °C, then a 1 A step
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's a clean, predictable curve — no surprise drop at 50 °C. Storage range is -40 °C to 80 °C; operating ambient is -25 °C to 70 °C.