Frame and trip unit — what In and Iu mean for the BOM line
The 1SDA068081R1 is an ABB XT4N 160 TMD 25-300 3p F F distribution circuit breaker. The 'In' rating of 25 A is the continuous current the breaker carries without tripping — it sets the overload threshold for the protected circuit. The 'Iu' of 160 A is the frame rating, meaning the XT4 chassis and contacts are rated for 160 A thermal current; the installed trip unit limits the actual protection to 25 A. The TMD trip unit is thermal-magnetic: the thermal element handles overload protection (inverse-time curve), and the magnetic element provides instantaneous short-circuit response. The adjustable range 25-300 refers to the thermal-magnetic setting range in A — this unit is fixed at 25 A, not field-adjustable.
Electrical ratings and panel fit
Rated voltage is 690 V AC, 50/60 Hz, covering standard low-voltage distribution networks up to 690 V line-to-line. Three-pole construction handles three-phase circuits. Dimensions 8.25 cm x 10.5 cm x 16 cm (LxWxH) — confirm DIN-rail or mounting plate space; the XT4 frame is a common ABB molded-case size.