EMC Standards
Samuel Burri
2013, EPFL
Outline
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Introduction
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History
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Compliance
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Requirements
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Procedures
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Example: WLAN
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Standards in power networks
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Conclusion
Samuel Burri, EPFL
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Introduction
EMC is concerned with unintentional generation,
propagation and reception of electromagnetic energy
and the unwanted effects it may induce.
[Source: Wikipedia]
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History
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1844 Morse: telegraph
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1892 Law of telegraph in Germany
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1895 Marconi: first radio transmission
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1906 IEC inaugural meeting
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1927 German Hochfrequenzgerätegesetz
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1933 CISPR founded
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1934 FCC established
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1989 EU EMC Directive
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Organisations (1)
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International
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International Electrotechnical Commision (CEI)
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International Special Committee on Radio Interference
(CISPR)
International Organization for Standardization
United States
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Federal Communications Commission
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Society of Automotive Engineers
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Military standards (MIL-STD)
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Organisations (2)
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Europe
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European Committee for Standardization (CEN)
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European Committee for Electrotechnical
Standardization (CENELEC)
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British Standards Institution
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Association for Electrical, Electronic and
Information Technologies (Germany, VDE)
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And several others...
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Compliance (1)
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“In general, compliance means conforming to a
rule, such as a specification, policy, standard or
law.” [Wikipedia]
A device needs to fulfill certain requirements
with respect to EMC/EMI to be put on the
market.
Compliance can be divided in emission and
susceptibility testing.
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Compliance (2)
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Each country decides its requirements.
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Three procedures can be distinguished:
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Verification: Product is tested by vendor or importer.
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Declaration of Conformity: Conformity is declared
by vendor or other, testing/registration can be
required.
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Certification: A test report is submitted to a third
party for approval.
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Compliance (3)
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Most requirements are harmonized between
countries and/or mutual recognition agreements
(MRAs) exist.
Products can be broadly categorized:
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Information technology equipment
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Radio equipment (Wifi, Mobile phones, …)
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Appliance (Stove, Washing machine, …)
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Medical / Automotive / Aerospace
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Compliance (4)
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FCC conducted emission limits:
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Compliance (5)
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FCC radiated emission limits:
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Example: Simple PCB
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10 MHz oscillator driving a 20cm trace with
74LS04 inverters on both ends.
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Battery supplies and ground trace to connect.
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Emissions exceed limits by as much as 30dB.
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Shielding helps.
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Example: WLAN (1)
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Four frequency ranges:
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2.4 GHz, 3.6 GHz, 4.9 GHz and 5 GHz.
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Only 2.4 GHz and 5 GHz can be used in most
countries.
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In the specification for the 5 GHz band not all
existing users were involved.
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Transmission Power Control and Dynamic
Frequency Selection were added.
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Example: WLAN (2)
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Power restriction and required non-interference
measures for WLAN equipment.
[Source: Wikipedia]
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Example: WLAN (3)
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Standards in Power Networks (1)
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The ideal case:
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Mono-phase
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Perfect sinusoid
Constant frequency
Constant effective value
Tri-phase
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Perfectly balanced phases
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Standards in Power Networks (2)
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European norm EN 50160
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Applied to medium and low voltage networks
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Quality is evaluated between provider and
consumer up to 35kV.
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Quality is judged by measures and statistical
indicators over intervals of up to one week.
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Quality needs to be assured regardless of
connected appliances. *
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A different quality can be agreed on by contract.
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Standards in Power Networks (3)
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In the case of non-conformance the provider
can:
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Offer a price reduction
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Increase network delivered power
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Provide additional equipment
The provider is responsible for the quality
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Standards in Power Networks (4)
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Measured parameters:
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Statistical:
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Frequency
Amplitude
Flicker
Phase mismatch
Harmonics
Remote control signals
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Standards in Power Networks (5)
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Measured parameters
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Definitions without strict limit:
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Undervoltage
Power interruption
Overvoltage
Interharmonic voltages
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Standards in Power Networks (6)
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Frequency
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Nominal frequency is 50 Hz.
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Values are obtained as average over 10 seconds.
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Of the 60'480 values collected over a week
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None must leave the interval [47 Hz; 52 Hz]
No more than 5% must leave [49.5 Hz; 50.5 Hz]
Continental Europe experiences very seldom more
than 0.2 Hz deviation.
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Standards in Power Networks (7)
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Amplitude
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Assessed for lines between 1kV and 35kV
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Averages over 10 minutes
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Out of the 1008 values for one week:
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No more than 5% must leave [0.9 x U; 1.1 x U]
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Standards in Power Networks (8)
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Flicker
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Rapid changes in voltage leading primarily to light
flickering
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Perception based assessment
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Statistical treatment over 2 hours intervals
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No more than 5% failures of 84 values
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Standards in Power Networks (9)
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Phase mismatch
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Evaluated by looking at symmetric components of
the power system
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Averages over 10 minutes
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No more than 5% failures of 1008 values
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Standards in Power Networks (10)
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Harmonics
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Evaluated on averages over 10 minutes
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Limit table for harmonics of different ranks
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Limit on the total harmonic distortion at 8% of the
nominal voltage
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Standards in Power Networks (11)
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Remote control commands
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Collected on 3 second intervals during one day.
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No more than 1% of 28'800 values above indicated
limits.
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Standards in Power Networks (12)
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Other definitions of EN 50160 without strict limits:
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Voltage drop: Voltage between 1% and 90% of nominal value
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Short interruption: Voltage below 1% for less than 3 minutes
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Long interruption: Voltage below 1% for more than 3 minutes
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Temporal over-voltage: Relatively long duration of over-voltage
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Transitional over-voltage: Over-voltage for some milliseconds
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Inter-harmonic voltage: Sinusoidal voltage not being a multiple of
50 Hz.
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Standards in Power Networks (13)
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IEC 60060-1 Lightning shock 1,2/50:
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T1 = 1.2μs +/- 0.36μs (30%)
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T2 = 50μs +/- 10μs (20%)
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Standards in Power Networks (14)
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IEC 60060-1 Switching shock
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T1 = 250μs +/- 50μs
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T2 = 2500μs +/- 1500μs
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Standards in Power Networks (15)
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IEC 61000-4-2 ESD discharge
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Standards in Power Networks (16)
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IEC 61000-4-4 Bursts (bouncing)
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5ns +/- 1.5ns rise time
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50ns +/- 15ns width at half maximum
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Standards in Power Networks (17)
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IEC 61000-4-12 Inductive load
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100 kHz frequency, 40% damping
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Standards in Power Networks (18)
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IEC 61000-4-12 Inductive load
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100 kHz frequency, 15% damping
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Conclusion
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EMC standards are a very broad topic and vary
from one country to the next.
EMC should be taken into account at all steps
in product development.
Working with experts / accredited laboratories
is highly recommended.
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Thank you for your attention
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Sources:
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Intertek: The Engineer's Guide To Global EMC
Requirements: 2007 Edition
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Clayton R. Paul: Introduction to Electromagnetic
Compatibility
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Pierre Zweiacker, EPFL: High Voltage lecture
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Wikipedia
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