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