Adjustable DC Load or Resistor for 0.5–10V, 1500A, for Parallel Heat Rise Testing

✨ The discussion addresses the challenge of performing parallel heat rise testing on power feed cables for conductor bars, requiring adjustable DC loads or resistors capable of handling 0.5 to 10 V at currents up to 1500 A per conductor, with two conductors running simultaneously (totaling approximately 3000 A at 2-5 V). The goal is to cycle 10 devices under test (DUTs) through 50 cycles each, heating them to a maximum temperature of 85°C over about 45 minutes per cycle, then cooling to ambient. Due to the high current and power dissipation (up to 15 kW), traditional series-pass elements or buck regulators pose significant thermal management challenges. The proposed practical solution involves using stainless steel water-cooled pipes as adjustable resistors by varying pipe length to balance current across multiple branches, since purchasing multiple high-current DC power supplies (e.g., 2000 A units) is cost-prohibitive. The existing infrastructure includes large DC power supplies rated at 5000 A and 10000 A fed from 3-phase 480 V. Alternative suggestions include using AC with autotransformers and step-down transformers feeding rectifiers, but DC is mandatory for the test. Supercapacitors were considered but deemed insufficient for the required heating duration. The key technical challenge is achieving fine voltage/current adjustment at very high DC currents with manageable power dissipation and cost.