Block NKD 25/1,17 is a three-phase, open-type line reactor (inductor) designed for 3 × 400 VAC systems on 50–60 Hz mains. It handles 25 A per phase, with an inductance of 1.170 mH and a short-circuit voltage of 4% at 400 VAC, helping limit fault currents and shape supply impedance. The unit weighs 3.80 kg and uses screw-clamp terminals for 10 mm² conductors, with DIN rail mounting and M4 fixing screws; insulation class IEC F (UL class 155), IP 00, and a 2500 VAC insulation test. The operating ambient range is −10 °C to +40 °C, and the model is listed as discontinued for new designs by BLOCK.
