Document: NRC Regulatory Guide
Document ID: 82021804-a487-471b-a76c-095315525b53
Document Type: regulatory_guide
Title: Guidelines for Evaluating Electromagnetic and Radio-Frequency Interference in Safety-Related Instrumentation and Control Systems (Rev. 2)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML1628/ML16281A531.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.180
CFR Part: 
CFR Title: 

Content:
µs 20 µs 50 ns The IEC 61000-4 tests comparable to the IEEE Std. C62.41.2-2002 tests are listed in Table 22. The test waveforms are the same and the test procedures are very similar. Hence, a direct interchange of the test methods is acceptable to the NRC staff. Table 22 Comparable SWC Test Methods IEEE Std. C62.41-1991 IEC Method Ring Wave 61000-4-12 Combination Wave 61000-4-5 EFT 61000-4-4 IEEE Std C62.41.2-2002 describes location categories and withstand levels for the surge waveforms that should provide an appropriate degree of SWC. Location categories depend on the proximity of equipment to the service entrance and the associated line impedance. Category C covers the exterior and service entrance. Category B covers feeders and short branch circuits extending to interior locations from the service entrance. Category A covers outlets and branch circuits in interior locations. The indicated withstand level at all locations is 6 kV peak voltage for all of the SWC tests, while the peak current varies according to location. The withstand levels presented in this regulatory position are based on Category B locations. The NRC staff has concluded that imposition of the 6 kV level on all tests without regard to location is overly conservative so an exception in the endorsement of the standard is taken to the specified withstand level. A determination of the withstand level classification that characterizes a particular location is more suitable for selecting applicable withstand levels than the application of a single conservative level as specified in the standard. This is a continuation of prior guidance, and the levels endorsed in Revision 1 of the guide for Category B locations remain acceptable to the NRC staff. Low withstand levels are appropriate for plant areas known for little load or capacitor switching and limited power surge activity, while elevated withstand levels are appropriate for locations where primary power is provided through connection to external