The Mean Well DRT‑960‑24 is a DIN‑rail mounted AC‑DC power supply that delivers 24 V DC at up to 40 A (960 W) from a 340–550 VAC three‑phase input with built‑in PFC and short‑circuit protection. Common failure modes include overheating of the internal switching MOSFETs or heat sink, degradation of the output capacitors under high ambient temperatures, and failure of the input voltage selector switch or over‑voltage protection circuitry when exposed to transient spikes above 550 VAC. First‑check diagnostics: verify that the unit is receiving correct AC input voltage and phase balance; measure the 24 V DC output for stability and ripple; inspect the heat sink and fan (if present) for dust buildup or mechanical damage, and confirm that all fuses and protection relays are intact.[oss-gpt-20b]