The ABB 1SDA051232R1 is a T2L-series molded case circuit breaker, rated 120 A, 3-pole, F IEC. This is the fixed thermal-magnetic version — no electronic trip unit, no adjustable curves. The F IEC designation means the breaker's instantaneous trip threshold is fixed at the IEC standard for that frame size, typically 5–10x In depending on the specific T2L variant. For a 120 A breaker, that translates to a magnetic trip somewhere in the 600–1200 A range, which governs short-circuit protection for feeders and downstream distribution.
Three-pole construction means it switches all three phases simultaneously, required for three-phase feeder protection. The F IEC curve is a fixed magnetic trip; unlike an adjustable electronic breaker, you cannot dial the instantaneous pickup up or down. That matters when coordinating with downstream breakers or motor starters: the fixed trip point is what it is, so selectivity studies need to account for that fixed threshold.
Integration context
For a panel builder, the fixed thermal-magnetic trip means no auxiliary power supply needed for the trip unit — it's self-powered from the line side. That simplifies wiring but also means no remote trip indication unless you add an auxiliary contact or shunt trip accessory.