EMC Standards. Samuel Burri 2013, EPFL

Transcription

1 EMC Standards Samuel Burri 2013, EPFL

2 Outline Introduction History Compliance Requirements Procedures Example: WLAN Standards in power networks Conclusion Samuel Burri, EPFL 2

3 Introduction EMC is concerned with unintentional generation, propagation and reception of electromagnetic energy and the unwanted effects it may induce. [Source: Wikipedia] Samuel Burri, EPFL 3

4 History 1844 Morse: telegraph 1892 Law of telegraph in Germany 1895 Marconi: first radio transmission 1906 IEC inaugural meeting 1927 German Hochfrequenzgerätegesetz 1933 CISPR founded 1934 FCC established 1989 EU EMC Directive Samuel Burri, EPFL 4

5 Organisations (1) International International Electrotechnical Commision (CEI) International Special Committee on Radio Interference (CISPR) International Organization for Standardization United States Federal Communications Commission Society of Automotive Engineers Military standards (MIL-STD) Samuel Burri, EPFL 5

6 Organisations (2) Europe European Committee for Standardization (CEN) European Committee for Electrotechnical Standardization (CENELEC) British Standards Institution Association for Electrical, Electronic and Information Technologies (Germany, VDE) And several others... Samuel Burri, EPFL 6

7 Compliance (1) 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. Samuel Burri, EPFL 7

8 Compliance (2) Each country decides its requirements. Three procedures can be distinguished: Verification: Product is tested by vendor or importer. Declaration of Conformity: Conformity is declared by vendor or other, testing/registration can be required. Certification: A test report is submitted to a third party for approval. Samuel Burri, EPFL 8

9 Compliance (3) Most requirements are harmonized between countries and/or mutual recognition agreements (MRAs) exist. Products can be broadly categorized: Information technology equipment Radio equipment (Wifi, Mobile phones, ) Appliance (Stove, Washing machine, ) Medical / Automotive / Aerospace Samuel Burri, EPFL 9

10 Compliance (4) FCC conducted emission limits: Samuel Burri, EPFL 10

11 Compliance (5) FCC radiated emission limits: Samuel Burri, EPFL 11

12 Example: Simple PCB 10 MHz oscillator driving a 20cm trace with 74LS04 inverters on both ends. Battery supplies and ground trace to connect. Emissions exceed limits by as much as 30dB. Shielding helps. Samuel Burri, EPFL 12

13 Example: WLAN (1) Four frequency ranges: 2.4 GHz, 3.6 GHz, 4.9 GHz and 5 GHz. Only 2.4 GHz and 5 GHz can be used in most countries. In the specification for the 5 GHz band not all existing users were involved. Transmission Power Control and Dynamic Frequency Selection were added. Samuel Burri, EPFL 13

14 Example: WLAN (2) Power restriction and required non-interference measures for WLAN equipment. [Source: Wikipedia] Samuel Burri, EPFL 14

15 Example: WLAN (3) Samuel Burri, EPFL 15

16 Standards in Power Networks (1) The ideal case: Mono-phase Perfect sinusoid Constant frequency Constant effective value Tri-phase Perfectly balanced phases Samuel Burri, EPFL 16

17 Standards in Power Networks (2) European norm EN Applied to medium and low voltage networks Quality is evaluated between provider and consumer up to 35kV. Quality is judged by measures and statistical indicators over intervals of up to one week. Quality needs to be assured regardless of connected appliances. * A different quality can be agreed on by contract. Samuel Burri, EPFL 17

18 Standards in Power Networks (3) In the case of non-conformance the provider can: Offer a price reduction Increase network delivered power Provide additional equipment The provider is responsible for the quality Samuel Burri, EPFL 18

19 Standards in Power Networks (4) Measured parameters: Statistical: Frequency Amplitude Flicker Phase mismatch Harmonics Remote control signals Samuel Burri, EPFL 19

20 Standards in Power Networks (5) Measured parameters Definitions without strict limit: Undervoltage Power interruption Overvoltage Interharmonic voltages Samuel Burri, EPFL 20

21 Standards in Power Networks (6) Frequency Nominal frequency is 50 Hz. Values are obtained as average over 10 seconds. Of the 60'480 values collected over a week 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. Samuel Burri, EPFL 21

22 Standards in Power Networks (7) Amplitude Assessed for lines between 1kV and 35kV Averages over 10 minutes Out of the 1008 values for one week: No more than 5% must leave [0.9 x U; 1.1 x U] Samuel Burri, EPFL 22

23 Standards in Power Networks (8) Flicker Rapid changes in voltage leading primarily to light flickering Perception based assessment Statistical treatment over 2 hours intervals No more than 5% failures of 84 values Samuel Burri, EPFL 23

24 Standards in Power Networks (9) Phase mismatch Evaluated by looking at symmetric components of the power system Averages over 10 minutes No more than 5% failures of 1008 values Samuel Burri, EPFL 24

25 Standards in Power Networks (10) Harmonics Evaluated on averages over 10 minutes Limit table for harmonics of different ranks Limit on the total harmonic distortion at 8% of the nominal voltage Samuel Burri, EPFL 25

26 Standards in Power Networks (11) Remote control commands Collected on 3 second intervals during one day. No more than 1% of 28'800 values above indicated limits. Samuel Burri, EPFL 26

27 Standards in Power Networks (12) Other definitions of EN without strict limits: Voltage drop: Voltage between 1% and 90% of nominal value Short interruption: Voltage below 1% for less than 3 minutes Long interruption: Voltage below 1% for more than 3 minutes Temporal over-voltage: Relatively long duration of over-voltage Transitional over-voltage: Over-voltage for some milliseconds Inter-harmonic voltage: Sinusoidal voltage not being a multiple of 50 Hz. Samuel Burri, EPFL 27

28 Standards in Power Networks (13) IEC Lightning shock 1,2/50: T1 = 1.2μs +/- 0.36μs (30%) T2 = 50μs +/- 10μs (20%) Samuel Burri, EPFL 28

29 Standards in Power Networks (14) IEC Switching shock T1 = 250μs +/- 50μs T2 = 2500μs +/- 1500μs Samuel Burri, EPFL 29

30 Standards in Power Networks (15) IEC ESD discharge Samuel Burri, EPFL 30

31 Standards in Power Networks (16) IEC Bursts (bouncing) 5ns +/- 1.5ns rise time 50ns +/- 15ns width at half maximum Samuel Burri, EPFL 31

32 Standards in Power Networks (17) IEC Inductive load 100 khz frequency, 40% damping Samuel Burri, EPFL 32

33 Standards in Power Networks (18) IEC Inductive load 100 khz frequency, 15% damping Samuel Burri, EPFL 33

34 Conclusion 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. Samuel Burri, EPFL 34

35 Thank you for your attention Sources: Intertek: The Engineer's Guide To Global EMC Requirements: 2007 Edition Clayton R. Paul: Introduction to Electromagnetic Compatibility Pierre Zweiacker, EPFL: High Voltage lecture Wikipedia Samuel Burri, EPFL 35