Electromagnetic Interference and Compatibility
Electromagnetic Interference (EMI) manifests as malfunctions at the component, equipment, subsystem and system level. Generally, EMI is an electrical disturbance from either a natural phenomenon (lightning, Electrostatic Discharge (ESD), etc.) or an electrical or electronic equipment that causes an undesired response (malfunction) in other equipment. These malfunctions can result in time consuming delays for investigation and troubleshooting to implement needed corrections. Electromagnetic Compatibility (EMC) looks at controlling those disturbances using installation techniques and other EMI and Radiofrequency Interference (RFI) reducing techniques that are implemented early in the design and installation of the equipment or system.
This Wiki introduces readers to existing EPRI EMC guidance related to the following topics:
Background[edit]
EMC received renewed attention in the early 1990s when nuclear power plants started replacing obsolete analog I&C systems with newer digital systems. Little guidance was available then on EMC for nuclear plants, and EPRI addressed the issue by publishing the Handbook for Electromagnetic Compatibility of Digital Equipment in Power Plants and a series of iterations the Guidelines for Electromagnetic Compatibility Testing of Power Plant Equipment (aka TR-102323) that reflected the increasing knowledge base and evolution of testing standards.
One issue of special note in early versions of the EMC testing guideline is the treatment of CS114, a high-frequency conducted susceptibility test that has proven particularly problematic for most equipment. The CS114 test levels recommended in earlier revisions of the EPRI EMC testing guideline were based on plant data acquired by EPRI in the early 1990s. The results of the reevaluation published in 2003 and 2007 EPRI reports indicated that the early data was misapplied, and less conservative test levels have been proposed in the revisions TR-102323 EMC testing guideline since 2008.
The other EMC issue identified in 2006 was the increasing use of cell phones and later wireless technologies, EPRI continues to work on assessments of new wireless devices susceptible of introducing electromagnetic interferences in the plant environment and incorporating the results of those assessments into newer versions of the TR-102323.
Finally, EPRI published in 2023 the Electromagnetic Compatibility Assessment Methodology (EMCAM) a risk-informed EMC assessment and control method allocation process for Digital I&C equipment, designed for use within the EPRI Digital Systems Engineering Framework.
Fundamentals[edit]
The two volumes of the Handbook for Electromagnetic Compatibility of Digital Equipment in Power Plants were published in 1994 and are since 2008 publicly available. The handbook explains the fundamentals of electromagnetic compatibility and provides guidelines for ensuring the electromagnetic compatibility of digital equipment in power plants. The handbook is applicable to digital equipment being installed in all types of power plants.
- Volume 1 - Fundamentals of EMI Control: presents a comprehensive and theoretical discussion of the fundamentals of EMI control. This volume is a reference to assist the reader in answering questions encountered while on the road to fully understand and prevent potential EMI problems.
- Volume 2 - Implementation Guide for EMI Control: presents a practical implementation guide for EMI control, beginning with design and procurement through testing and installation; it also includes information on operation and maintenance.
Training Materials[edit]
EPRI provides training on EMI & EMC fundamentals, browse EPRI Training and Development Platform for future training opportunities.
For self-paced learning opportunities on the topic, review:
- Engineering Technical Training Module (ETTM) – EMI and RFI Noise Analysis: a computer based training course updated in 2018 that allows students to learn the types and characteristics of electrical disturbances found in a power plant environment.
- Engineering Technical Training Module (ETTM) - EMI and RFI Noise Analysis, Version 1.0: a computer based training course that provides training for power plant engineers on the types and characteristics of electrical disturbances found in a power plant environment.
- EMI Qualification of Digital Equipment Upgrades - Revision 2, Version 3: a computer based training course that presents the recommended generic EMI susceptibility and emissions test levels for use in establishing equipment EMC for nuclear power plant applications.
EMC Testing and Control Guidance[edit]
As discussed in the background the EMI & EMC knowledge increased in the industry with the practical experience and research completed and this was reflected in the different iterations on the Guidelines for Electromagnetic Compatibility Testing of Power Plant Equipment (aka TR-102323). The TR-102323 table below describes the main changes and provides links for access in EPRI website.
In addition to continuing with the evolution of the testing guidance, EPRI has developed a risk informed methodology that integrates with the Digital Systems Engineering Framework as the risk-informed testing and control method allocation process for EMC. The EMCAM section below describes the main changes and provides links for access tp its most current version in EPRI website.
TR-102323 Guidelines for Electromagnetic Compatibility Testing of Power Plant Equipment versions access table[edit]
| Revision # | Publication year | Notes |
|---|---|---|
| Revision 5 and the [ Errata version] | 2019 & 2024 | The latest revision, incorporates all learnings from past versions and contains in the appendixes the technical bases for the changes. It also adds additional guidance and clarification to various sections of the document based on current events and issues experienced by the nuclear power industry. This includes the addition of an example exclusion zone calculation with clarification supporting each equation recommended for use by the guideline, arc welding EMI suppression guidance, adjustable and variable frequency speed drives EMI suppression guidance, lighting system EMI suppression guidance, wireless emissions control guidance, a summary of lessons learned and operating experience from nuclear industry related EMI events. |
| Revision 4 | 2013 | This revision of the EPRI guidance made better use than previous ones of EMC testing standards commonly used by equipment vendors and suppliers and generally reduced differences with the recommendations of NRC Regulatory Guide 1.180, Revision 1. Where differences remained, the bases for the Revision 4 position were provided. One issue of special note in Revision 4 is its treatment of CS114. The CS114 test levels recommended in previous revisions of this report and in Regulatory Guide 1.180, Revision 1, were based on plant data acquired by EPRI in the early 1990s. The latest results indicate that the early data was misapplied, and less conservative test levels were recommended. |
| Revision 3 | 2004 | Not available on EPRI website, revision 3 incorporated the results of the 2003 reevaluation of the conducted susceptibility limits and proposed less conservative test levels. |
| Revision 2 | 2000 | This version revised the limits to reduce excessive conservatism, based on plant operating experience since the first version of the guide was released and broader frequency ranges to accommodate newer telecommunication devices. |
| Revision 1 | 1997 | Revision 1 reflected modifications to the original document. |
| Revision 0 | 1994 | Not available on EPRI website, this first issue received NRC approval through a safety evaluation report (SER) in 1996 and became a de facto standard within the U.S. nuclear industry. The SER report has been maintained in the appendixes of the subsequent revisions of this guidance. |
EMCAM - A risk-informed approach to EMC[edit]
The Electromagnetic Compatibility Assessment Methodology (EMCAM) is a risk-informed I&C equipment assessment and control method allocation process designed as an element of the Digital Systems Engineering Framework to:
- remove conservatism during equipment assessment (where acceptable) for a given application and
- tailor the testing scope and level and control method allocation for a given application.
This proposed method can potentially reduce testing costs and provide a more flexible decision-making during:
- testing specification and assessment, and
- allocation of additional electromagnetic interference (EMI) controls.
EMCAM enables a user to decide which technical or administrative control methods to apply during system design and assessment to achieve a risk reduction target (RRT) value and Control Effectiveness Profile (CEP) score provided from a corresponding hazards analysis process, such as Hazards and Consequences Analysis for Digital (HAZCADS). EMCAM uses the CEP score value and equipment location information to identify recommended EMC testing parameters (acceptance criteria, scope and limits) and additional controls for nuclear facility I&C equipment modifications.
Technical bases for testing limits[edit]
Testing limits in the TR-102323 "recommended practices" and EMCAM were originally developed from data collected by EPRI in 1993-1994 and are documented them. The limits have been questioned serval times as overly conservative mainly due to data misinterpretation. Two reports have been issued to review the bases for the data in particular for the conducted emissions susceptibility (CS) test, CS114.
- Review of High Frequency Conducted Susceptibility Limits: Assessment of CS114 Test Limits in TR-102323: published in 2003, it documents a review of the bases for the high-frequency conducted emission susceptibility (CS) test limits recommended in EPRI Report TR-102323 (Revisions 0-2) for testing and qualifying equipment to be installed in nuclear power plants. The primary purpose of the investigation was to provide additional information to support EMI Working Group discussions of the problems that are consistently experienced with this part of EMI qualification testing. The report provides recommendations on potential ways to develop additional bases for revising the current recommended limits for this testing.
- Review of High Frequency Conducted Susceptibility Limits for Electromagnetic Compatibility Testing: published in 2007, it documents the technical basis for the CS114 test levels in Regulatory Guide 1.180, Revision 1, and provides technical justification for changes to the existing industry and NRC guidance on CS114 qualification tests.
Technology Assessments and Troubleshooting Methods and Results Reports[edit]
Another areas of work for EPRI were:
- the development of a troubleshooting guide to trace and correct EMI malfunctions, and
- the assessment of new technologies that once introduced in the plants could cause EMI.
Troubleshooting EMI[edit]
The Electromagnetic Interference (EMI) Troubleshooting Guide assists practitioners with the development of a troubleshooting methodology that can be used by utility personnel to diagnose and resolve EMI issues. The report provides the necessary background and supporting information to develop an EMI troubleshooting guide that will help save time and money by making it easier to trace, diagnose and resolve EMI issues in the field. It may be used by utilities to directly implement its guidance at a facility or to aid in interactions with vendors by ensuring a common understanding and compliance with reputable electromagnetic compatibility standards and techniques.
Technology Assessment Reports[edit]
EPRI continues to assess new technologies introduced at the plants to identify EMI issues and propose control methods to ensure EMC compatibility. Available assessments are listed in the table below:
| Title | Publication date | Description |
|---|---|---|
| Wireless Technology Assessment: Analysis of Radiated Emissions from Common Phones, Laptops, and Tablets | 2018 | Provides the bounding exclusion zones for three wireless protocols (Wi-Fi, Bluetooth, and LTE) and examines field strengths generated within the far-field of wireless transmission for a subset of wireless devices during normal operation. |
| EPRI Robotics Research: Electromagnetic Compatibility Assessment of SPOT Robotic Platform | 2022 | Documents the completed electromagnetic compatibility testing of a Spot robot for radio frequency emissions, and susceptibility characterization in accordance with EPRI product 3002015757, Guidelines for Electromagnetic Compatibility Testing of Power Plant Equipment, Revision 5 to TR-102323. |
| Li-Fi Wireless Communications: Technology Evaluation for Utility Applications | 2023 | This report includes discussions not only about radiated and electromagnetic emissions, but also examines the potential benefits and challenges of Li-Fi technologies related to security, spectrum output, and communication performance. |
| Wireless Technology Assessment: Analysis of Radiated Emissions from Common Phones, Laptops, and Tablets - 2024 Update | Pending | This report provides an update to the guidance contained in the previous report to include a sampling of the latest cellular phones, tablet devices, and other devices using these additional wireless communications protocols. The information contained in it is intended to provide the nuclear industry with example data from wireless technology to support their own internal evaluations of the technology and the establishment of associated exclusion zones. |
EMI Documented Experiences Analysis[edit]
EPRI has documented the analysis of EMI events to inform the industry of EMI risks and offer suggestion on how they can be further mitigated.
| Title | Publication year | Description |
|---|---|---|
| Indian Point-2 Flash Photography Event | 2009 | This report presents the results of an independent assessment by the EPRI Electromagnetic & Radio Frequency Interference Working Group on a flash photography event at the Indian Point-2 (IP-2) nuclear power plant.
|
| Assessment of Electromagnetic Interference Events in Nuclear Power Plants | 2011 | This report seeks to identify, collect, and analyze the EMI-related incidents in an effort to understand the level and trends in these events. Beyond trends, the analysis probes the causal factors of the events. The fundamental physics of the events is studied with the objective of using an improved understanding of the physics of interference for evaluating the range of mitigations that are possible. |
Additionally, Guidelines for Electromagnetic Compatibility Testing of Power Plant Equipment: Revision 5 to TR-102323 in its appendix L includes a summary of lessons learned and OE obtained from the 2011 report mentioned in the table above and EMC events presented in EPRI EMI Qualification of Digital Equipment Upgrades in Nuclear Power Plants - Computer-Based Training.