PETRAIII is a 3rd generation sychrontron light-source starting operation in 2009. The annual availability usually reaches a level over 97%. For this level of availability a high reliable pre accelerator is mandatory. The pre accelerator complex for PIII includes a Linac (LINACII), an accumulator ring (PIA) und a booster synchrotron (DESYII). With the constant-current (“top-up”) operation mode of PETRA III, the pre accelerators must deliver beam every few minutes. As a consequence they have to run continuously. Maintenance periods are rather limited. At the same time, the reliability and operation stability must be very high. To fulfill this goals several technical systems are designed redundant and the complex runs in a completely automated operation mode.