It belongs to the XT2 frame size, which is the compact, high-performance line in ABB's molded case portfolio.
What the 125A TMA trip unit means for your application
The 125A TMA trip unit provides thermal overload protection (inverse-time curve) for cable and equipment, plus magnetic short-circuit protection with an adjustable instantaneous pickup. On the XT2 frame, this rating typically covers feeder circuits and smaller motor loads up to about 55 kW at 400 VAC.