Document: NUREG-0800
Document ID: 97120913-d26f-4324-ab62-22f3f5b73925
Document Type: srp
Title: and 8.3.2.
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0636/ML063600410.pdf
Revision Date: 2023-06
Chapter: 8
Section ID: 8.3.1
CFR Part: 
CFR Title: 

Content:
of time Ts equals 1 second, any short-circuit current determined from the envelope of the current wave at the time of the maximum crest, whose value does not exceed 2.74 times the rated short-circuit current, and whose rms value I determined over the complete 1 second period does not exceed the rated short circuit current considered above. The fault current chosen should be that due to a fault on the system at a point which causes the largest I2t heating of the circuit breaker. The short-time current-carrying capability should be demonstrated with a current-carrying test as described in IEEE Std C37.013. It is not to be inferred that the generator circuit breaker is to be capable of interrupting after the required short-time current-carrying capability duty until it has cooled down to normal heat run temperature. (vi) Duty Cycle Capability. The duty cycle capability of the generator circuit breaker should be demonstrated by a series of symmetrical and asymmetrical close-open cycle tests as specified in IEEE Std C37.013. The time between two operations to interrupt short circuit current shall be the rated value of 30 minutes specified in the standard. (vii) Transformer Excitation Current Switching Tests. The circuit breaker interruption of an unloaded station main and/or auxiliary transformer excitation current should not generate excessively high surge voltages which could damage the connected bus and transformer insulation. This should be verified by test. (viii) Rated Continuous Current-Carrying Test. The thermal capability of the circuit breaker should be demonstrated by a test at its continuous current rating. The test should be in accordance with the requirements and ratings contained in IEEE Std C37.013. For applications which use two generator circuit breakers in a parallel circuit, a test should be conducted 8.2-33 Revision 4 - March 2007 to determine the time to reach the maximum permissible temperature on the most limiting component of the breaker when