The "C" model is a stripped-down version aimed at price-sensitive markets. It replaces the full alphanumeric LCD with a combination of bright LED status indicators (Mains On, Generator On, Load On Generator, Alarm) and a smaller digital readout. While it loses some advanced programming features, it retains the essential AMF logic and engine protection. The AC01C is common on entry-level automatic standby generators for home use.
Even robust systems fail. Here is a cheat sheet for frequent errors: pramac ac 01 generator monitor control system ac01 mp ac01c