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:
s 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 going from the rated continuous current to twice rated continuous current. (ix) Mechanical Endurance Life Test. No-load mechanical operation tests are made on a complete generator circuit breaker or on a single pole of the generator circuit breaker if all three poles are identical to ensure its satisfactory operation in normal service without excessive maintenance. In practical applications, the generator circuit breaker is connected to the bus duct by means of flexible copper or aluminum connections. The enclosure of the generator circuit breaker may be welded to the enclosure of the bus duct. These conditions should be taken into account during the tests. A sufficient number of no-load mechanical operations should be performed by the circuit breaker to provide a reasonable indication of its mechanical reliability and life. The demonstrated life should be adequate for the plant life expectancy. (x) Rated Interrupting Time. The rated interrupting time of the generator circuit breaker is the maximum permissible interval between the energizing of the trip circuit at rated control voltage and rated fluid pressure of the operating mechanism and the interruption of the main circuit in all poles on an opening operation. Typical values are approximately 60–90 ms with the actual time being dependent on the rated short-circuit current. For generator circuit breakers equipped with resistors, the interrupting time for the resistor current may be longer. The interrupting time of a generator circuit breaker is demonstrated for different currents by the test duties cycles specified in IEEE Std C37.013. Interrupting times of test results, when expressed in cycles, shall be in cycles of the power frequency. (xi) Short Circuit Current with Delayed Current Zero. It is generally