MCCB for starter protection — 125 A, TM120M release, 220 kA at 240 V
The Siemens SENTRON 3VA1112-6MH32-0AD0 is a 3-pole molded case circuit breaker (MCCB) designed specifically for starter protection, meaning it's built to handle the high inrush and repetitive switching of motor starters while providing short-circuit and overload protection. Its TM120M thermal-magnetic release gives a fixed 125 A rating across the 40 °C to 50 °C ambient range, then derates gradually to 114 A at 70 °C. The interrupting capacity is 220 kA at 240 V, 154 kA at 415 V, and 75.6 kA at 440 V — figures that put it in the high-fault-current class for industrial distribution. Rated insulation voltage is 800 V.
What the ratings mean for your panel
The 125 A continuous rating at 40-50 °C means this MCCB can carry a full 125 A load without derating in a typical ventilated enclosure. Above 55 °C, the thermal curve pulls back — at 70 °C it's good for 114 A. For a motor starter circuit, the TM120M release provides the magnetic short-circuit trip plus thermal overload curve matched to motor protection profiles. The 220 kA SCCR at 240 V means it safely interrupts faults up to that level without cascading upstream — critical for high-fault panels near large transformers. The 3-pole configuration handles three-phase loads. The 800 V rated insulation voltage gives headroom for 690 V systems.
Integration notes — auxiliary switches and basic switch
The 3VA1112-6MH32-0AD0 ships with a pre-configured basic switch (3VA11126MH320AA0) and three auxiliary switches HQ for status feedback to a PLC or indication panel. The auxiliary switches are wired separately from the main power path. No undervoltage release, no ground-fault monitoring, and no communication function — this is a straightforward thermal-magnetic MCCB for motor starter duty. Dimensions are 70 mm deep, 76.2 mm wide, 130 mm high, fitting standard panel mounting.