What This Is
It's a compact, high-performance breaker sized for panelboard and distribution board integration, typically used to protect cable and busbar systems in commercial and light industrial mains.
The description string XT2S 125 EKI encodes the frame size and breaking capacity. '125' is the frame rating in amps — this is a 125 A frame. 'EKI' typically denotes the interrupting rating and accessory configuration; on ABB's XT2S platform, that usually maps to a standard breaking capacity for 400 VAC distribution. The exact kA rating at the service voltage should be confirmed from the nameplate or the full datasheet for the specific variant.