Document: NUREG-0800
Document ID: 853719df-a6ea-408b-8d43-5956155abc38
Document Type: srp
Title: and 8.3.2.
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1007/ML100740246.pdf
Revision Date: 2023-06
Chapter: 8
Section ID: 8.3.1
CFR Part: 
CFR Title: 

Content:
conditions as the symmetrical current. 8.2-34 Revision 5 - May 2010 The circuit breaker should have, as a minimum, the capability of interrupting the maximum asymmetrical and symmetrical fault current available at the instant of primary arcing contact separation. This current should be calculated by assuming a bolted three phase fault at a point on the system which causes the maximum amount of fault current flowing through the generator circuit breaker. The fault current interrupting capability (short circuit current rating) of the circuit breaker should be demonstrated by performing a series of tests similar to those called for in IEEE Std C37.013. The tests should include close/open (CO) operations and should be performed at the circuit breaker minimum rated air pressure and control voltage and with a rated transient recovery voltage as described in the standard for system-source faults and generator- source faults. (iv) Rated Transient Recovery Voltage (TRV). The ability to withstand rated TRVs, as specified in IEEE Std C37.013 for rated symmetrical and asymmetrical currents, is demonstrated during short-circuit tests. Both inherent circuit transient recovery voltage and power frequency recovery voltage must be considered when demonstrating the rating of a generator circuit breaker. Additional information and guidance on TRV is provided in IEEE Std C37.011 (Reference J). (v) Short-Time Current-Carrying Capability. The generator circuit breaker shall be capable of carrying for a period 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