The Cutler‑Hammer IQ DP‑4000 is a three‑phase power supply module that feeds the IQ DP‑4000 electrical distribution monitor; it receives its input from the same source it measures and supplies regulated DC to the control system. Common failure modes include blown fuses or relays due to overcurrent, insulation breakdown of internal wiring under high ambient temperatures, and degradation of the voltage regulator ICs when operating outside specified line ranges. First‑check steps: verify incoming AC phase voltages and continuity of the power leads; inspect all fuses and relay contacts for signs of arcing or corrosion; review any error codes displayed on the DP‑4000 panel for indications of overvoltage, undervoltage, or temperature excursions.[oss-gpt-20b]