Document: NUREG-0800
Document ID: 899b3059-69f1-4f7b-bead-1d58e5f4870f
Document Type: srp
Title: Revision 5 - March 2007
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0705/ML070550080.pdf
Revision Date: 2023-06
Chapter: 7
Section ID: 7
CFR Part: 
CFR Title: 

Content:
the objective of the isolation and the specific type and configuration of the isolation device (e.g., relay, isolation amplifier, optical-electronic device). The MCF represents the application of the maximum credible alternating current (AC) and direct current (DC) voltages and currents that are applied to the device in common and differential modes (as defined by IEEE Std 100-2000, “The Authoritative Dictionary of IEEE Standards Terms 7th Edition”) that exist based on the installation of the device. Common mode refers to faults between both signal terminals and a common reference plane (ground) and causes the potential of both sides of the transmission path to be changed simultaneously and by the same amount relative to the common reference plane (ground). Differential mode refers to faults between the signal terminals that cause the potential of one side of the signal transmission path to be changed relative to the other side. The mode of application should satisfy the following guidelines for test configurations. For isolation of safety circuits from non-safety circuits: • MCFs and surges should be applied between the signal output terminals of the (non-safety) circuits (differential mode) and between any output terminal and ground (common mode). • Surges should be applied to power terminals. The guidance of IEEE Std C62.45-2002 is acceptable for surge testing at the power input. • The signal input terminals should be monitored to assure that no unacceptable interactions (degradations or distortions) between the safety and non-safety circuits would occur. For isolation between redundant safety circuits: • MCFs should be applied between the signal input terminals (differential mode) and between any input terminal and ground (common mode); the output should be monitored to assure that no unacceptable interactions (degradations or distortions) between redundant safety circuits will occur. • Surges should be applied to power terminals. The guidance of