RKL4621 by Bosch Rexroth Indramat

The RKL4621 is a motor power cable manufactured by Bosch Rexroth Indramat for the RKL Motor Power Cables series. It links servo drives to synchronous motors in automated axes, carrying three-phase power together with auxiliary control cores so that motion controllers can monitor temperature or brake signals through the same harness. By combining power and auxiliary conductors in one jacketed assembly, the cable simplifies routing inside machine tools and material-handling gantries.

This model is built for continuous-motion applications because the copper bundle is rated for 5,000,000 flex cycles in cable chains. A line capacitance of 1.2 nF/m keeps displacement current low, helping drives maintain stable PWM switching. DC losses are minimized by conductors that measure only 0.554 ohm/km at 20 °C, so voltage drop stays within tolerance on long runs. During dynamic travel, the bending radius must not fall below 7.5 × D, which helps prevent shield fatigue. The PUR outer sheath is finished in RAL 2003 (orange) for clear visibility, and each of the four power cores has a cross-section of 35.0 mm² to carry high surge currents without excessive heating.

The cable has a nominal diameter of 30.8 mm, so it fits standard drag-chain inserts. For static cabinet runs, the minimum bend radius is 5 × D, allowing tighter routing where movement is absent. The load-side operating voltage is rated to 600 VAC, matching the output stage of compatible Rexroth inverters. One end terminates in an INS0381/C35 motor connector, and the opposite end uses an RLS0724/K35 drive connector, which eliminates field crimping. Four equally sized power conductors and four 1.5 mm² control cores sit under an oil-resistant PUR jacket, helping the cable maintain insulation integrity in coolant-rich machine environments.