MCCB for line protection — 200 A, 4-pole, TM240 release
The Siemens 3VA1220-4GF42-0HC0 is a SENTRON molded case circuit breaker (MCCB) rated for line protection duty. It carries a rated continuous current Iu of 200 A across four poles, with the TM240 thermal-magnetic overcurrent release providing both overload and short-circuit protection. The interrupting ratings are 121 kA at 240 V, 75.6 kA at 415 V, 25 kA at 440 V, and 11.9 kA at 690 V — figures that govern the available fault current the breaker can safely clear at each voltage level without upstream coordination failure. This breaker is dimensioned at 70 mm deep, 140 mm wide, and 158 mm tall, fitting into standard SENTRON panel cutouts and busbar arrangements. It includes 2 auxiliary switches (HQ type) and a shunt trip (STL) for remote tripping, but has no communication module, undervoltage release, phase failure detection, or ground fault monitoring — it is a straightforward line-protection device, not a multifunction power monitor.
Thermal derating and ambient limits
The 200 A rating holds flat from 40 °C up to 50 °C ambient. Above that, derating begins: 194 A at 55 °C, 188 A at 60 °C, 182 A at 65 °C, and 176 A at 70 °C. The operating ambient range is -25 °C to +70 °C; storage range is -40 °C to +80 °C. For a panel builder, the 70 mm depth and IP40 front protection mean the breaker mounts in a standard distribution board with a gland plate — no special enclosure depth required, but the front face is not sealed against washdown.
Coordination and selectivity note
For selectivity studies, the TM240 release is a fixed thermal-magnetic design — no electronic adjustment. The 100% N-conductor protection rating means the neutral pole is fully rated, not derated. The latching endurance is 15,000 operations, adequate for distribution duty but not for frequent switching. The shunt trip (STL) requires an external control voltage to trigger; the auxiliary contacts (2 HQ switches) provide status feedback to a PLC or indicator lamp.