CHAPTER 2 Flashcards
EMC
ELECTROMAGNETIC COMPATIBILITY
ABILITY OF A DEVICE, EQUIPMENT, OR SYSTEM TO OPERATE PROPERLY IN ITS INTENDED ELECTROMAGNETIC ENVIRONMENT WITHOUT INTRODUCING SIGNIFICANT ELECTROMAGNETIC INTERFERENCE (EMI) INTO THE ENVIRONMENT.
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EMI
ELECTROMAGNETIC INTERFERENCE
THE TRANSFER OF ELECTROMAGNETIC ENERGY FROM ONE DEVICE OR SYSTEM TO ANOTHER DEVICE OR SYSTEM OPERATING IN THE SAME ENVIRONMENT THAT CAUSES INTERFERENCE WITH NORMAL OPERATION OF THE DEVICES OR SYSTEMS.
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ELECTROMAGNETIC EMISSON
THE PHENOMENOM BY WHICH ELECTROMAGNETIC ENERGY EMANATES FROM A SOURCE. EMISSIONS CAN BE EITHER RADIATED OR CONDUCTED WHEN COUPLED INTO A GIVEN DISTURBED CIRCUIT. SUCH EMMSISIONS MAY BE DIVIDED INTO TWO CATEGORIES: INTENTIONALLY EMITTED SIGNALS AND UNITENTIONAL EMMISIONS.
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ELECTROMAGNETIC IMMUNITY
THE ABILITY OF A DEVICE, EQUIPMENT, SYSTEM TO PERFORM WITHOUT DEGREDATION IN THE PRESENCE OF AN ELECTROMAGNETIC DISTURBANCE.
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EMR
ELECTROMAGNETIC RADIATION
RADIATION COMPOSED OF OSCILLATING ELECTRICAL AND MAGNETIC FIELDS AND PROPOGATED THROUGH A MEDIUM.
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ESD
ELECTROSTATIC DISCHARGE
THE SUDDEN FLOW OF ELECTRICITY BETWEEN TWO ELECTRICALLY CHARGED OBJECTS CAUSED BY CONTACT.
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GROUNG LOOP
TWO PARALLEL PATHS THAT HAVE IDENTICAL CONDUCTIVE TERMINATIONS TO TWO SEPERATE GROUNDING REFERENCES.
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RFI
RADIO FREQUENCY INTERFERENCE
THE DEGREDATION OF A DESIRED SIGNAL AT THE RECEPTOR END CAUSED BY RADIO FREQUENCY DISTURBANCE WITHIN THE RADIO FREQUENCY SYSTEM WHICH IS USUALLY COMPRISED IN TE FREQUENCY RANGE THAT INCLUDES LF, MF, HF, AND VHF.
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TWO DEVICES ARE USING OVERLAPPING OPERATIONAL FREQUENCIES WITHIN THE SAME EM ENVIRONMENT. WHAT IS THE LIKELY AFFECT ON THE POTENTIAL FOR EMI IN THIS ENVIRONMENT?
THE POTENTIAL FOR EMI IS LIKELY TO INCREASE UNDER THESE CONDITIONS.
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NAME 4 MECHANISMS THAT CAN CREATE COUPLING BETWEEN TWO CIRCUITS OR SYSTEMS.
- CONDUCTIVE COUPLING
- INDUCTIVE COUPLING
- CAPACITIVE COUPLING
- ELECTROMAGNETIC COUPLING
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WHAT TYPE OF COUPLING MAY OCCUR WHEN A COMMON AC BRANCH CIRCUIT IS SHARED BETWEEN TWO DEVICES?
CONDUCTIVE COUPLING
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WHAT CAUSES INDUCTIVE COUPLING?
MAGNETIC FIELDS
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WHAT CAUSES CAPACITIVE COUPLING?
ELECTRIC FIELDS
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NAME 3 ESSENTIAL ELEMENTS OF ANY EMC PROBLEM
- SOURCE OF AN EMI ELECTROMAGNETIC ENERGY TRANSFER
- SUSCEPTIBLE DEVICE OR SYSTEM THAT CANNOT PERFORM AS DESIGNED, CONFIGURED, OR PROGRAMMED BECASUE OF THE EMI EVENT.
- COUPLING PATH THAT PROMOTES THE DISTURBANCE
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NAME 8 EXAMPLES OF EMR
- GAMMA RAYS
- X-RAYS
- UV LIGHT
- VISIBLE LIGHT
- IR RADIATION
- RADAR
- MICROWAVES
- RADIOWAVES
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WHAT IS THE SPEED OF LIGHT?
300,000 km/s (186,300 mi/s) IN A VACUUM
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NAME THE 2 CHARACTERISTICS THAT ARE USED TO DISTINGUISH ELECTECTROMAGNETIC WAVES.
- WAVELENGTH (EXPRESSED IN METERS)
- FREQUENCY (EXPRESSED IN HERTZ)
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HOW MANY FREQUENCY BANDS ARE RECOGNIZED BY THE ITU?
12
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TRUE OR FALSE
VISIBLE LIGHT REPRESENTS THE LARGEST PORTION OF THE ELECTROMAGNETIC SPECTRUM.
FALSE, VISIBLE LIGHT REPRESENTS ONLY A SMALL PORTION OF THE ELECTROMAGNETIC SPECTRUM.
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NAME THE 3 PRIMARY PATHS THROUGH WHICH CONDUCTED COUPLING MAY AFFECT ELECTRONIC DEVICES.
- INPUT SIGNAL LINES
- OUTPUT SIGNAL LINES
- UTILITY OR PREMISES ELECTRICAL POWER DISTRIBUTION
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NAME THE 4 PRIMARY CONDITIONS THAT ALLOW RADIATED INTERFERENCE TO ENTER ELECTRONIC DEVICES
- PROXIMITY TO INTERFERING SOURCES
- MISSING OR INADEQUATE GASKETS/ENCLOSURES
- MISSING OR INADEQUATE BONDING AND GROUNDING SYSTEM COMPONENTS.
- MISSING OR INADEQUATE DEVICE OR CABLE SHIELDING
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TRUE OR FALSE
ELECTRICAL CODES DO NOT GENERALLY PROVIDE FOR EMC
TRUE, ELECTRICAL CODES DO NOT PROVIDE FOR EMC.
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WHAT IS AN ELECTROMAGNETIC FIELD?
AN AREA OF ENERGY THAT SURROUNDS ELECTRICAL DEVICES
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WHAT TYPE OF CHARGE CREATES AN ELECTRIC FIELD?
STATIONARY
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WHAT TYPE OF CHARGE CREATES AND MAGNETIC FIELD?
MOVING (ELECTRICAL CURRENTS)
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NORMALLY, IT IS NOT PRACTICAL TO CONTROL EXTERNAL SOURCES OF EMI. WHAT METHODS SHOULD THE ICT DESIGNER USE TO ADDRESS THIS TYPE OF EMI INSTEAD?
REVERT TO METHODS THAT PROMOTE SYSTEM IMMUNITY.
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WHAT IS A RELIABLE AND EFFECTIVE TECHNIQUE FOR MITIGATING THE EFFECTS OF RADIO FREQUENCY INTERFERENCE ON TELEPHONE SETS?
DEPLOYING SHIELDED OR SCREENED STRUCTURED CABLING SYSTEMS IN CONCERNED AREAS.
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WHY IS IT DIFFICULT TO TO DETERMINE A DEVICES EMC?
BECAUSE ITS VALUE IS RELATIVE TO THE ENVIRONMENTIN WHICH IT WILL OPERATE.
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NAME 2 COMPONENTS OF EMC.
- EMISSION
- IMMUNITY
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WHAT UNITS OF MEASURE ARE USED TO DESCRIBE MAGNETIC FIELDS?
AMPERES PER METER
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WHAT FREQUENCY SPECTRUM IS TYPICALLY USED FOR MEASURING CONDUCTED INTERFERENCE?
100 kHz TO 30 MHz
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WHAT FREQUENCY SPECTRUM IS TYPICALLY USED FOR MEASURING RADIATED INTERFERENCE?
30 MHz TO 5 GHz
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HOW IS IMMUNITY TO RADIATED EMISSIONS DETERMINED?
BY EXPOSING THE DEVICE BEING MEASURED TO A SPECIFIED ELECTROMAGNETIC FIELD AND MONITORING ITS PERFORMANCE.
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