Full PLC & HMI Retrofit on a Hebei Huayu Carton Production Line

A carton production line arrived with a catastrophic fault — a short circuit between 24VDC and 230V AC phase that destroyed most of the electrical and electronic components across the machine. Nothing was spared. The intervention covered the full scope of the damage: 🔍 Root cause diagnosis — traced the short circuit path through the panel and identified every damaged component ⚡ VFD repair — component-level repair on damaged variable frequency drives 🔧 VFD installation & commissioning — installed replacement drives and programmed all parameters (acceleration, deceleration, frequency limits, control mode) 🖥️ HMI repair — diagnosed and repaired the damaged human-machine interface 🧠 New PLC installation — replaced the failed controller with a Schneider Electric Modicon TM221, rewrote the full ladder logic program 🔌 Full rewiring — stripped and rebuilt all panel wiring from scratch following proper industrial standards The machine went from completely dead to back in production — no original documentation, no backup program, built from zero.