Grounding & Shielding: The Essence of EMC Design (DS354)

SynopsisBackground
“One of the problems with grounding is the term itself... it’s too vague
Often a single ground may serve multiple needs, with different rule to each”
The discipline of Electromagnetic Compatibility (EMC) is concerned with the design of Electronic Systems, while minimizing electromagnetic coupling and interference from within the system and between the system to its environment.
The discipline of electromagnetic compatibility covers and requires involvement in a wide range of other fields of engineering, system engineering and electronic engineering, etc.
Meeting the strict EMC standards, as well as ensuring the satisfactory performance of the equipment in its intended electromagnetic environment requires the implementation of technical measures into the system’s design.
The concept of “grounding” is probably among the most important, yet less understood topic of electronic design, often considered as "black magic". Yet – grounding forms an inseparable part of all electronic and electrical designs, from circuit through system up to installation design. Grounding is implemented for EMC and ESD protection, for safety purposes, for lightning and surge protection, etc.
Shielding, on the other hand, is a necessity for avoiding electromagnetic field coupling from and into equipment enclosure. Adequate shielding is necessary to enhance immunity of equipment, and reduce emissions from the equipment enclosure.
Grounding and shielding are two of the essential concepts in EMC design. No design will be acceptable without them being properly implemented.

Synopsis
This three-day comprehensive course provides the trainees with the necessary tools for identification, analysis and understanding of the electromagnetic phenomena related to electronic equipment and system-level grounding and shielding.
This course is intended to shed some light on the concepts and pitfalls of the grounding and shielding - two essential and inseparable concepts in EMC design.
The course will cover the concept of Grounding and its topologies, leading to the implementation of grounding from circuit to system. With respect to shielding – the course will cover issues such as the shielding properties of metals, and the compromises in shielding, which are the main objective of shield design.
Mathematical derivations and calculations kept to the minimum necessary, whereas the practical applications will be extensively discussed.
Practical solutions to practical problems, as well as “real life case histories” are used as examples, and case studies are extensively used along the Course. Bring your interference problems and return with practical and useful solutions.

What You Will LearnParticipants in the Course will
• obtain a systematic approach to the concepts of grounding and shielding
• acquire a fundamental knowledge of the problem and interference sources in electrical and electronic systems
• understand the importance and application of grounding and shielding of equipment and systems and acquire a “common language” with the electronic and mechanical design engineers for achieving total system compatibility
In addition, participants are encouraged to bring forward actual design problems and questions they encountered, which the instructor will attempt to assist in their solution.

Who Should AttendThe Course is intended for system and equipment design engineers and technicians, who are involved in the design and development, qualification or engineering management of electronic and electrical systems and their installation.

PrerequisiteKnowledge of electronic circuit theory.

Course MethodologyThis course is presented classroom style.

Course Duration3 days, 9am - 5pm

Course StructureModule 1: Introduction
1. Basics of EMC
• Nature of an EMI problem
• EMI Sources, Victims and Interactions
• “EMI - The Silent Threat”: A Video Presentation

2. Signals and Coupling Modes
• Spectral contents of signals
• Interference modes – Common Mode vs. Differential Mode Signals
• Signal Coupling and Propagation: “Path of Least Inductance”
• Transmission Line Basics and Frequency Considerations

Module 2: Grounding
3. Grounding Essentials
• Reasons and Rationale for Grounding
• Basic Grounding Topologies

4. Power Grounds
• Power Grounding Design
• Safety Considerations in Power Grounding

5. Signal Grounding
• Signal Return vs. "Ground" Return
• The Grounding Tree

6. Cable Grounding and Shielding
• Basics of Field to Cable Interaction
• Cable Shields
• Signal Cable Grounding vs. Cable Shield Grounding

7. Grounding Implementation on Printed Circuit Board
• Grounding Objectives on PCBs
• Grounding Approaches on PCBs
• Analog Circuits Grounding
• Digital Circuits Grounding
• Mixed Digital and Analog Circuit Grounding
• Chassis Grounding on PCBs

8. Box and System-Level Grounding
• The Interconnect Dilemma
• Multiple Grounds and Solutions

9. Ground-Loop Interaction and Coupling (GLIC)
• CM-to-Differential Mode Conversion
10. GLIC Control Techniques
• Isolation Transformers
• Signal Transformers and BalUns
• Balanced Line Drivers and Receivers
• Optical Isolators
• RF Blocking Chokes
• Signal Filters

11. Grounding Myths and Pitfalls
• “Single point Grounds”
• “Ground Loops”

12. Grounding-Related Case Histories
13. Bonding
• Bonding Techniques
• Corrosion Control in Bonding

14. Field and Cable interaction
• Emission of fields from cables
• Coupling of fields to cables
• Crosstalk between cables
• Cable classification and design

Module 3: Shielding
15. Basics of Shielding
• Shielding Effectiveness
• Shielding Materials

16. Shield Discontinuities
• Aperture Leakage
• Aperture (Window and Slot) Control
• Shielded Windows
• Conductive Gaskets

17. Equipment and System Shield Design
• Box-Level Shield Design
• Rack Shield Design

18. Shield Integrity Violations
• Shield Penetrations
• Shield Discontinuities

Module 4: Summary and Wrap-up
19. Summary
20. Q&As