Table 4: Severity and occurrence analysis of faults both at startup and runtime phase in liquid-cooled frequency converter.

Assessment Fault Severity Occurrence SO Priority  Startup faults Air in cooling system 9 3 27 1 Phase module Cooling channel clogging 9 2 18 1 Runtime faults    Pump delivery pressure Decreasing 8 2 16 2 Pipe clogging 8 2 16 2 Pipe leakage 8 2 16 2 Air-cooled heat Exchanger cooling effect Decreasing 6–8 2 16 2 Valve blockage 6–8 2 16 2 Temperature sensor defect 9 3 27 1 Phase model loosening 9 1 9 3