York Emc Testing

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Emission Testing

David Hambley MSc. C. Eng.

MIEE


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Contents!Common EMC tests

What are we testing for?

What do we need to do the test?

What are the important parameters?

How do we do it?

Which standards?

Emission Testing


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Introduction

!Electromagnetic Compatibility Ability of equipmentto function

satisfactorily in its electromagnetic

environment without introducingintolerable electromagneticdisturbances to anything in thatenvironment.


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EMC testing

Conducted Radiated

Emissions

Conducted Radiated

Immunity

Electromagnetic Compatibility


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Emissions

!Why worry? Protect the electromagnetic

environment

Protect radio services Emergency services

Commercial broadcasts

Prevent interference with otherequipment intended to operate in thesame environment


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Emissions!Standards contain:

Limit lines

Test method

!Basic emission standards EN55011 Industrial, scientific and medical

EN55013 Broadcast receivers

EN55014 Household appliances

EN55015 Lighting apparatus

EN55022 Information Technology Equipment


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Conducted emissions

!AC power port Conducted electrical noise

Switched mode power supplies

150kHz-30MHz (most equipment)

9kHz-30MHz (lighting)

!Aim to protect LW/MW/SW broadcasts

!Main equipment required Spectrum analyser or receiver

Line Impedance Stabilisation Network (LISN)


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Conducted emissions


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Conducted emissions!LISN

Inserted into power line

Allows measurement of RF voltage

Provides defined impedance eg 50//50H

Provides some noise isolation from mains supply

!Some precautions

EUT current

Earth leakage current Filtered supply

Ambient radiated signals


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Harmonic emissions!AC power port

Conducted electrical noise

Linear power supplies

50Hz-2kHz

!Aim to protect electrical supply quality Prevent conductor burnout

Protect supply waveform

!Main Equipment required 50Hz power amplifier

Power analyser


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Harmonics/flickerequipment


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Harmonic emissions

!50Hz power amplifier Powers equipment under test

Removes harmonics present on

incoming supply!Power analyser

Measures the harmonics generated

!Standard EN61000-3-2


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Flicker!AC power port

Disturbances impressed on electrical supply

Simulates effect on 60W light bulb

!Aim to protect electrical supply quality

Prevent excessive voltage deviations

Protect supply waveform

!Main Equipment required

50Hz power amplifier

Flicker impedance

Software algorithms


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Flicker

!50Hz power amplifier Powers equipment under test

Provides a stabilised voltage supply

!Flicker impedance Defined impedance across which the

flicker voltage is measured

!Standard EN61000-3-3


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Radiated emissions!Enclosure port and associated cabling

Microprocessor frequencies

Switched mode power supplies

DC brushed motors

30MHz-1000MHz (most equipment) 9kHz-30MHz (additionally for lighting)

!Aim to protect

Commercial broadcasts Emergency services

Mobile phone services


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Radiated emissions

!Main equipment required Spectrum analyser or receiver

Antenna

Open Area Test Site (OATS)

4m mast

Turntable

Ellipse free from reflecting objects


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Radiated emissions

EUTNon-metallictable

3m or 10m

mast

antenna

cable runningundergroundto control room

ground plane

EUT

Antenna

xx 10m3m

ground plane

CISPR Ellipse

Position ofmeasurementequipment if notunderground


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Typical open area test site


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Covered open area test site


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Measuring detectors

!Hardware detectors contained in spectrumanalysers and receivers

!4 detectors used in EMC testing

Peak

Peak hold (max hold)

Quasi-peak

Average

!Each detector has unique characteristics


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Peak detector!Standard detector

!Detects signal peak or envelope worstcase levels

!Allows measurements to be made quickly!Not referenced in commercial EMC

standards (except one railway standard)

!Used For pre-compliance testing

In conjunction with a quasi-peak detector


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Peak hold detector

!Variant of peak detector!Display updated if the amplitudemeasured is greater on current

sweep than on previous sweeps!Useful for measuring emissions from

cyclic equipment

!Not referenced in commercial EMCstandards


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Quasi-peak detector!Referenced by all commercial EMC

standards

!Based upon subjective human responseto pulsed interference e.g. car ignition

!Provides a weighted output

!Weighted output based upon pulse

repetition frequency (PRF)!Output up to 43.5dB less than peak

detector


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Quasi-peak detector! Long charge/discharge times

! Measurements are slow

! 9k-150k 150k-30M 30-1000MRBW (kHz) 0.2 9 120Charge Tc (ms) 45 1 1Discharge Td (ms) 500 160 550

! Conducted emission =53 minutes per phase

! QP detector used in conjunction with peak detector

! Only emissions from EUT are measured using QP detector


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Average detector!Referenced in commercial EMC

standards for conducted emissiontests

!Measures the average level!Average level


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Other emissions tests!Conducted emissions on telecoms ports

Similar to that on ac ports using ISN

!Conducted disturbance power

Applies to household appliances mainly

AC power port

Emissions measured using clamp on wheels

!Discontinuous interference

Measures transient conducted emissions (spikes)

AC power port

Requires oscilloscope to capture spikes


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Immunity Testing


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Immunity

!Why worry? Ensure adequate protection against

interference

Annoyanceo Interference on radio or TV

Safety critical

o Lift electronicso Vehicle ABS systems


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Immunity!Standards contain:

Test levels

Test method

!Basic immunity standards

EN61000-4-2 Immunity to ESD

EN61000-4-3 Radiated immunity

EN61000-4-4 Immunity to EFT/B

EN61000-4-5 Immunity to surge

EN61000-4-6 Conducted RF immunity

EN61000-4-8 Power frequency magnetic immunity

EN61000-4-11 Voltage dips and interruptions


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Introduction!Emission tests have limits

Under limit = pass, over limit = fail

!How can immunity be assessed?

What parameters should be monitored?

How should they be quantified?

What degradation is acceptable?

To the manufacturer? To the user?

Standards contain performance criteria


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Introduction! Performance criteria B

The apparatus shall continue to operate as intended after thetest. No degradation of performance or loss of function isallowed below a performance level specified by themanufacturer, where the apparatus is used as intended. Theperformance level may be replaced by a permissible loss of

performance. During the test, degradation of performance is,however, allowed. No change of actual state or stored data isallowed.

If the minimum performance level, or the permissible

performance loss, is not specified by the manufacturer, theneither of these may be derived from the product descriptionand documentation and what the user may reasonably expectfrom the apparatus if used as intended.


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Immunity to ESD!Enclosure port

Areas which can be touched under normaloperation

!Increasing importance

!More sensitive electronics!More hostile environment Particularly the home

!Aim to protect semiconductor devices Temporary disturbance or destruction of

components!


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Immunity to ESD


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Immunity to ESD


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Immunity to ESD!Main equipment required

ESD simulator (gun)


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Immunity to ESD!Standard

EN61000-4-2

!Two types of discharge

Contact (typically 4kV or 6kV)

To metallic surfaces

Coupling planes Air (typically 8kV)

Insulating surfaces


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Immunity to ESD!Two types of application

Direct

To the equipment under test

Contact discharge

Air discharge

Indirect

To coupling planes

Contact discharge only Horizontal coupling plane (HCP)

Vertical coupling plane (VCP)


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Radiated immunity!Enclosure port and associated cabling

!Electromagnetic fields from intentionaltransmitters

Mobile phones

Other radio communications

!80MHz-1000MHz frequency range

>1GHz testing will be required in the future

!Analogue circuits are vulnerable Measuring circuits eg thermometers

Audio equipment


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Radiated immunity!Main equipment required

Anechoic chamber

Signal generator

Power amplifier Power meter

Antenna

Field probe


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Radiated immunity


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Radiated immunity!Standard

EN61000-4-3

!Requirements 0-6dB field uniformity over 1.5m x 1.5m area

80MHz-1000MHz

Test level: 3V/m, 10V/m or 20V/m depending uponenvironment

1kHz 80% amplitude modulated field

Pre-calibrated field

!Monitoring the equipment under test CCTV

External monitoring


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Immunity to EFT/B!Electrical fast transient/burst

interference!Results from electrical switching

Thermostats

Equipment being switched on & off

!5ns rise time and 50ns half life

!Applied in bursts 15ms in duration

!300ms repetition rate

I it t EFT/B


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Immunity to EFT/B


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Immunity to EFT/B!Standard

EN61000-4-4!Requirements

Direct coupling

AC power port DC power port

Typically 1kV or 2kV depending upon environment

Indirect coupling Signal cables

Control cables

Typically 1kV or 2kV depending upon environment


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Immunity to EFT/B!Main equipment required

EFT/B generator

Capacitive coupling clamp

!


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Immunity to surge!Similar to EFT/B

!Voltage & current surge

Nearby lightning strikes

Switching of inductive loads

!Surge waveforms

Voltage waveform specified

Current waveform specified

Immunity to surge


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Immunity to surge

Immunity to surge


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Immunity to surge


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Immunity to surge!Standard

EN61000-4-5

!Requirements Applied in single pulses

Normally 1 minute apart

At 0, 90, 180 & 270 on 50Hz waveform

Line to line coupling Surge applied between lines with respect to earth

Typically 1kV

Line to earth coupling Surge applied between line and earth

Typically 2kV


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Immunity to surge!Main equipment required

Surge generator

Coupling/decoupling network


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Conducted RF immunity! Injection of RF currents into cables

!Electromagnetic fields from intentionaltransmitters

Lower frequency that radiated immunity

LW/MW/SW broadcasts

!150kHz-80MHz frequency range

Overcomes antenna inefficiency

!Analogue circuits are vulnerable Measuring circuits eg thermometers

Audio equipment


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Conducted RF immunity!Main equipment required

Shielded enclosure

Signal generator

Power amplifier

Power meter

Coupling/decoupling networks (CDNs)

Injection clamp

Conducted RF immunity


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Conducted RF immunity


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Conducted RF immunity!Standard

EN61000-4-6

!Requirements

150kHz-80MHz (230MHz)

Test level: 3Vrms, or 10Vrms depending uponenvironment

1kHz 80% amplitude modulated field

Pre-calibrated injection level

Use of CDNs preferred

Use of ferrite clamp with feedback as an alternative


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Immunity to VDI!Voltage dips & interruptions

!AC power port

!Supply perturbations

Voltage dips Deviation from nominal 230V supply

Resulting from equipment being switched on

Voltage interruptions Loss of supply

Resulting from supply interruption


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Immunity to VDI!Standard

EN61000-4-11

!Requirements Inrush capability of facility to be measured

Voltage dip Specified as a X% dip for Yms

Typically 30% for 10ms & 60% for 100ms

Voltage interruptions

Specified as a X% dip for Yms Typically >95% for 5000ms

Normally commencing at zero crossing point (but notalways)


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Immunity to VDI!Main equipment required

VDI generator

Oscilloscope


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Summary!Common EMC tests

What are we testing for?

What do we need to do the test?

What are the important parameters?

How do we do it?

Which standards?

Documents

York Emc Testing