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.
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