Q385 : Effects of Fault Clearing Time on Safety Thresholds
Question I get different values for the safety thresholds computed for a fault clearing time of 0.5 seconds when I compare the results of the 2002 version of CDEGS with older versions. What has changed?
Answer The difference is due to a new computation method for the decrement factor. For a fault duration of 0.5 seconds, it is now recommended to use the exact formula for the decrement factor for all values of the fault duration. Previously, the recommendation was to use 1 for all fault duration times >= 0.5 s.