This document discusses electromagnetic interference (EMI), including definitions of key terms, sources of EMI, types of EMI, effects of EMI, and units used to specify EMI parameters. It addresses conducted and radiated EMI, natural and man-made sources of EMI, intra-system and inter-system EMI, and thermal and non-thermal biological effects of EMI. Measurement units covered include voltage, current, electric field strength, and magnetic field strength.

9. 1.EMI EMC Definitions and units of parameters
2.Sources of EMI
3.Conducted and Radiated EMI
4.Transient EMI.
5.Units of specifications
6.Civilian standards and military standards.

10. Class-1

11. Recap : definitions
 1.what is EM disturbance ?
 2.what is EMI ?
 3.what is RFI ?
 4.EMC ?
 5.EMS ?
 6.Intra EMI ?
 7.Inter EMI ?
 8.Intentional EMI ex:
 9.Unintentional EMI ex :
 10.How EMI occurs ?
 11.What is E-field coupling & H- field coupling ?
 12.Fraunhoffer limit ?

12. Wide spread usage of all electronic and electrical
equipment

13. EM disturbance : EM phenomenon
*****Ex:noise,unwantedsg,propagtn medium
EMI : degradation in the system
RFI: degradation in reception of wanted
EMC : *** ability of a system to work satisfactorily in EM
environment.
EMS : capability of a device or ckt to respond to the unwanted
electrical noise.

14. EMI / EMC
• EMI is defined as the undesirable signal which causes
unsatisfactory operation of a circuit or device.
• EMC is defined as the ability of electronic and communication
equipment to be able to operate satisfactorily in the presence of
interference and not be a source of interference to nearby
equipment.
• EMS Electromagnetic susceptibility (EMS) is the capability of a
device to respond to EMI.

17. Basic Types of EMI:
These are of two types. They are
•Intra-EMI:
EMI is said to be intra-EMI if the functional characteristics of
one module within an electronic equipment or system is disturbed
due to EMI from another module. *Ex:
b) Inter-EMI:
EMI is said to be inter-EMI if the functional characteristics of
one equipment is disturbed due to EMI generated by another
equipment. *Ex:

18. How EMI can be tackled systematically ?
 Possible strategies could be adopted .
 A)design
 B)design
 C)define
 i) Understand ----------emission process  enough to be able
to control them with in limits.
 ii) Establish ------------ design criteria  to achieve
immunity against permitted EMI levels.
 iii) evolve ----------procedures  to test equipment against
defined limits & establish the process of regulation.
D) Suppress techniques

19. Sources of EMI :

20. EMI SOURCES
These are divided mainly into two types.
I. Natural and
II. Man-made
I. Natural EMI sources are again of the following
types:
Terrestrial and Extra-Terrestrial.
Terrestrial Sources
These are atmospheric thunderstorms, lightning
discharges and precipitation static.
Extra-Terrestrial Sources
These are sun-disturbed & quiet, cosmic noise and radio
stars.

21. Man made noise:
 A)systems : i) comm /radar/navigation
 Fluorescent tube light,
 Automobile ignition systems /industrial such as arc
welders heaters etc..
 Appliances such as microwave ovens,mixers etc..
 B) circuits/components : local
osc,switches,motors,relays,nonlinear ckt
elements,armatures,latching contractors,corona,rusty
contacts,circuit breakers.etc..

22. Natural noises :
 Terrestrial Sources: thunderstorms, lightning
 discharges and precipitation static.
 These are atmospheric EM noise  caused by
electric discharge in the atmosphere.
 Cloud to gnd discharge : (thunders )

23. Cloud to cloud discharge:
(lightning)
 Static charges acquired by a cloud -------produces a
static electric field .
Electro static discharge :
 Accumulated static electric charges are discharged.
 When occur ? O.O
 Ex:wool and glass

24. Celestial noises
 Sun ,stars,
 Galaxy.

25. EMI receptors :

27. Effects of EMI :

28. The common effects of EMI
(i) Annoying Effects
Very often, momentary and random disturbances in
radio and television reception occur.
(ii) Disturbing Effects
Unwanted reset and change of status in settings in
computers and digital equipment is noticed due to EMI.
The malfunctioning of computer key boards are noticed.
(iii) Catastrophic Situations
The burning of electronic components, loss of data,
change of threshold settings, improper or unwanted
operations and sometimes biological hazards occur very
often.

29. B.T.P.MADHAV

30. B.T.P.MADHAV

31. BIOLOGICAL EFFECTS OF EMI / EMR
EM waves, light, heat, x-ray and gamma rays are all different forms
of electromagnetic radiation.
However, they differ in their wavelength. These radiations have
hazardous effects on men and material.
The effects can be divided into two categories.
7.Thermal Effects
2. Non-thermal Effects.

34.  Radiated emissions and susceptibility :
 Field strength (volts/meter or tesla )
 Conducted emissions and susceptibility :
 Voltage & current (volts and amperes)
 Voltage : volts,dBv,dBmv,dBμV
 Current :
 Electric field :v/m dBv/m,dBmv/m
 Magnetic field : w/m or tesla .