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J2019L
March 23, 2019, 10:00 PM
A 70 sqmm copper cable can withstand a short circuit current of 8.05kA for 1 second. If the protection relay operates in 0.2 second, then what is the maximum fault current that the cable can tolerate?

The solve method seems to apply: 8.05kA * sqrt(1/0.2) = 18.0 KA
Is there someone can find the source document to proof this concept?
Wanderer20001us
April 25, 2019, 10:13 AM
A 70 sqmm copper cable can withstand a short circuit current of 8.05kA for 1 second. If the protection relay operates in 0.2 second, then what is the maximum fault current that the cable can tolerate?

The solve method seems to apply: 8.05kA * sqrt(1/0.2) = 18.0 KA
Is there someone can find the source document to proof this concept?

I2T = I2T. Damage energy remains constant.