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EMI EMC
EMI EMC
EMI EMC
EMI EMC
EMI EMC
EMI EMC
EMI EMC
EMI EMC
EMI EMC
EMI EMC
EMI EMC
EMI EMC
EMI EMC
EMI EMC
EMI EMC
EMI EMC
EMI EMC
EMI EMC
EMI EMC
EMI EMC
EMI EMC
EMI EMC
EMI EMC
EMI EMC
EMI EMC
EMI EMC
EMI EMC
EMI EMC
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EMI EMC

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Electromagnetic Interference and Electromagnetic Compatibility, Design constraint in Electronics, High Frequency Electronics

Electromagnetic Interference and Electromagnetic Compatibility, Design constraint in Electronics, High Frequency Electronics

Published in: Engineering, Business, Technology
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  • 1. Electromagnetic Interference & Electromagnetic Compatibility BY VIKRAM KUMAR ASSISTANT PROFESSOR DEPARTMENT OF INSTRUMENTATION & CONTROL JSS ACADEMY OF TECHNICAL EDUCATION, NOIDA
  • 2. What are EMI and EMC ? • An electromagnetic disturbance which may degrade the performance of an equipment or causes malfunction of the equipment, is called electromagnetic interference (EMI). • Electromagnetic compatibility (EMC) is a near perfect state in which a receptor functions satisfactorily in the common electromagnetic environment, without introducing intolerable electromagnetic disturbance to any other devices / equipment's / system in that environment.
  • 3. Commonly experienced EMI Situations • Power supply ‘Hum’ in radio sets • Crackling sound on radio/TV during lightening • White spots on TV picture due to nearby mobile • Jitter in Digital signal reading in lab • Cross talk on telephones • Radio silence under HT wires.
  • 4. Critical EMI Situations • Loss of transmission. • Malfunction of life support equipment- Pacemaker. • Malfunction in critical process control in industry. • Malfunction of aircraft equipment. • Unintended of detonation of explosive devices. • Malfunction of Missile guidance system.
  • 5. Intrasystem Vs. Intersystem EMI • Intrasystem interface comes about as a result of self-jamming or undesirable emission coupling within a system. • Intersystem EMI is the interference between two more discrete systems or platforms which are frequently under separate user control. Intersystem EMI is more difficult to control
  • 6. A system is said to be electro magnetically compatible if :-  It doesn't cause interference with other system .  It is not susceptible to emissions from other systems.  It doesn’t cause interference with itself. The methodologies to prevent EMI are:-  Suppress the emissions at source point, the best method to control EMI .  Make the coupling path as inefficient as possible.  Make the receiver less susceptible to emission. Purpose and Methodology for EMC System
  • 7. EMI on Human Body An electric field on an unshielded person discharges to the ground, while the magnetic field ”permeates" the body inducing a magnetic flux that generates secondary electric fields inside the body.
  • 8. Power line interferences with the human body 50Hz distribution in the body. The red areas show where the strongest currents are. Absorption of cell phone radiation with concentrations in the neck.
  • 9. Important techniques to control EMI at source point are • Proper Grounding–single point, multi point or hybrid grounding depending upon the frequency of operation. • Shielding –Metal barrier is used to suppress coupling of radiated EM energy into the equipment. • EMI Filtering-used to suppress conducted interference on power, signal and control lines. • PCB layout –Proper PCB design from the early design stage is required. EMI control techniques at source
  • 10. EM Interference
  • 11. Independent earth electrodes, a solution generally not acceptable for safety and EMC reasons Installation with a single earth electrode EMC - Earthing principles and structures
  • 12. Installation with multiple earth electrodes
  • 13. Common Mode & Differential Mode Interference An item of equipment with external cables AB and CD, in an electric field. . Three loops have been created by the above circuit Loop 1 ABCDA, Loop 2 ABEFA & Loop3 DCEFD
  • 14. ‘First aid’ responses to conducted interference. • Parallel capacitor at (a) reduces differential mode voltage developed at the input. • Series inductance shown at (b) reduce common mode current flow to ground by stray capacitance. Remedial or ‘First Aid’
  • 15. Example of common-mode impedance coupling Common Mode Coupling
  • 16. Types of Interference Types of Interference
  • 17. Capacitive Coupling Example of capacitive coupling Cable shielding with perforations reduces capacitive coupling
  • 18. Inductive Coupling Example of inductive coupling
  • 19. Radiated Coupling Definition of radiated coupling Examples of radiated coupling
  • 20. Countermeasures • Inductive Coupling 1. Twist the wires to reduce the loop area 2. Run the twisted wire close to ground 3. Design ground & return planes with minimal penetrations • Capacitive Coupling 1. Separating the source and the receiver and properly connecting shield will reduce capacitive coupling • Radiated Coupling 1. Reducing bandwidth 2. Using good signal routing 3. Shielded enclosure 4. Reducing the loop Size
  • 21. References • Center of Electronics Test and Engineering, Noida. • SAMEER Kolkata Centre EMI-EMC Division • SAMEER Chennai – CEM Division • EMV 2012 Düsseldorf- The latest EMC highlights and trends • Dr Jeff Chambers, Understanding Common Mode Interference , Westbay Technology Ltd • Wiki EIG (Electrical Installation Guide)
  • 22. Thank You! Q?

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