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:
rence between the 10% and 90% amplitude points on the leading edge of the waveform. The amplitude of the waveform decays with each peak being 60% of the amplitude of the preceding peak of the opposite polarity. The peak voltage value of the Ring Wave is given in Table 23. For the IEC test, the withstand levels correspond to Level 3 and Level 4 for the low and elevated surge conditions, respectively. During the performance of the test, the equipment under test should not exhibit any malfunction or degradation of performance beyond specified operational tolerances when subjected to the Ring Wave. Acceptable performance of the equipment under test should be defined in the test plan by the end user or testing organization according to the applicable equipment, subsystem, or system specifications. Figure 5.1 100-kHz Ring Wave DG-1333, Page 28 5.2 IEEE Std. C62.41 Combination Wave and IEC 61000-4-5 The Combination Wave involves two exponential waveforms, an open-circuit voltage and a short-circuit current. It is intended to represent direct lightning discharges, fuse operation, or capacitor switching on the ac power leads of equipment and subsystems. The open-circuit voltage waveform has a 1.2-µs rise time and an exponential decay with a duration (to 50% of initial peak level) of 50 µs. The short-circuit current waveform has an 8-µs rise time and a duration of 20 µs. Plots of the waveforms are shown in Figures 5.2 and 5.3. The rise time is defined as the time difference between the 10% and 90% amplitude points on the leading edge of the waveform. The duration is defined as the time between virtual origin and the time at the 50% amplitude point on the tail of the waveform. Virtual origin is the point where a straight line between the 30% and 90% points on the leading edge of the waveform intersects the V=0 line for the open-circuit voltage and the i=0 line for the short-circuit current. The peak value of the open-circuit voltage of the Combination Wave and the peak