Model-Based Fault Detection and Isolation of a Liquid-Cooled Frequency Converter on a Wind Turbine

Table 3

Severity level of fault in liquid-cooled frequency converter.

Effect	Severity of effect	Ranking
Hazardous	The operation of system may not be safe and/or not in compliance with government regulations (f.x. IEC or UL standard)	9
Very high	The primary functionalities are lost	8
High	The system is only operable at reduced performance	7
Moderate	The overall system performance is affected but the system is functional	6
Low	Minor parts of the system operating at reduced performance	5
Very low	The fault is noticed but does not affect the overall system performance	4
Minor	The fault is often noticed but does not affect the overall system performance	3
Very minor	The fault is only noticed in rare cases	2
None	No noticeable effect	1