10.3 StorageThe DC link of the KEB COMBIVERT is equipped with electrolytic capacitors. If theelectrolytic aluminium capacitors are stored de-energized, the internal oxide layer is re-moved slowly. Due to the leakage current the oxide layer is unrenewed. If the capacitorstarts running with rated voltage there is a high leakage current which can destroy thecapacitor.In order to avoid defectives, the KEB COMBIVERT must be started up depending on thestorage period in accordance with the following specification:Storage period < 1 year• Start-up without special measuresStorage period 1…2 years• Operate drive converter one hour without modulationStorage period 2…3 years• Remove all cables from the power circuit; especially of braking resistor or module• Open control release• Connect variable transformer to drive converter input• Increase variable transformer slowly to indicated input voltage (>1 min) and remainat least on the specified time.Voltage class Input voltage Residence time400 V0…280 V 15 min280…400 V 15 min400…500 V 1 hStorage period > 3 years• Input voltages as before, however double the times per year. Eventually changecapacitors.After expiration of this start-up the KEB COMBIVERT can be operated on nominal ratingconditions or delivered to a new storage.10.3.1 Cooling circuitThe cooling circuit must be completely empty if a unit shall be switched off for a longerperiod. The cooling circuit must be blown out additionally with compressed air at tem-peratures below 0°C.61MAINTENANCE
