Elec­tro­mag­netic com­pat­i­bil­ity test­ing in EMC lab

EN 61000–4–6:2014 Elec­tro­mag­netic com­pat­i­bil­ity (EMC) — Part 4 – 6: Test­ing and mea­sure­ment tech­niques — Immu­nity to con­ducted dis­tur­bances, induced by radio-​frequency fields (IEC 61000 – 4-6:2013)

Ana­log: IEC 61000 – 4-6:2013 Elec­tro­mag­netic com­pat­i­bil­ity (EMC) — Part 4 – 6: Test­ing and mea­sure­ment tech­niques — Immu­nity to con­ducted dis­tur­bances, induced by radio-​frequency fields

Replace: EN 61000 – 4-6:2009 Elec­tro­mag­netic com­pat­i­bil­ity (EMC) — Part 4 – 6: Test­ing and mea­sure­ment tech­niques — Immu­nity to con­ducted dis­tur­bances, induced by radio-​frequency fields


New in this edi­tion:
• Updates in CDN usage;
• Cal­i­bra­tion of clamps;
• Reor­ga­nized clause 7 regard­ing test setup and injec­tion meth­ods;
• Annex A is ded­i­cated to EM and decou­pling clamps;
• Annex G which now addresses the mea­sure­ment uncer­tainty of the volt­age test level;


Scope
Inter­na­tional stan­dard EN 61000 – 4-6:2014 relates to con­ducted immu­nity require­ments of elec­tri­cal and elec­tronic equip­ment to elec­tro­mag­netic dis­tur­bances cre­ated by RF trans­mit­ters in fre­quency range 150kHz-​80MHz. This stan­dard is not applic­a­ble to equip­ment have no wires (power sup­ply cables, ground­ing cables, sig­nal, telecom­mu­ni­ca­tion cables etc.).


Gen­eral
Elec­tronic activ­ity in radio fre­quen­cies in any equip­ment cre­ates elec­tro­mag­netic field. When wires and cables are exposed to these fields, cur­rents and volt­ages are cre­ated in these con­duc­tors. Radio, TV, radar, smart­phones etc. use radio fre­quency energy to per­form their func­tions, there­fore emit high power fields. These fields can be con­ducted through cables to other equip­ment or radi­ated in air and induced in cables. Cur­rent test method ver­i­fies equip­ment sus­cep­ti­bil­ity to high power elec­tro­mag­netic fields induced in cables. These dis­turb­ing fields are approx­i­mated by elec­tric and mag­netic near-​fields. Dis­tur­bances are induced in cables directly using cou­pling decou­pling devices. Dis­tur­bances are induced in com­mon mode regard­ing ground ref­er­ence plane. Cable sys­tems con­nected to an equip­ment are assumed to be in res­o­nant mode (λ/​4, λ/​2 open or folded dipoles) and as such are rep­re­sented by cou­pling and decou­pling devices hav­ing a com­mon mode imped­ance of 150Ω with respect to a ref­er­ence ground plane. Where pos­si­ble the EUT is tested by con­nect­ing it between two 150Ω com­mon mode imped­ance con­nec­tions: one pro­vid­ing an RF source and the other pro­vid­ing a return path for the cur­rent.


Test level
Inter­na­tional stan­dard EN 61000 – 4-6:2014 define fol­low­ing immu­nity lev­els in fre­quency range 150kHz-​80MHz. Test lev­els are expressed in RMS val­ues.


Dur­ing immu­nity tests these sig­nal is 80% ampli­tude mod­u­lated using 1kHz sine wave to sim­u­late actual threats. Exam­ple of ampli­tude mod­u­la­tion is shown below.

Test lev­els must be selected accord­ing to spe­cific prod­uct stan­dards or generic stan­dards that defines lev­els in accor­dance to elec­tro­mag­netic envi­ron­ment. For equip­ment intended to be oper­ated in a wide range of envi­ron­ments fol­low­ing clas­si­fi­ca­tion can be used:
Class 1: Low level elec­tro­mag­netic envi­ron­ment. Typ­i­cal envi­ron­ment next to low power trans­ceivers and envi­ron­ments at least 1km far away from radio and tele­vi­sion trans­mit­ters.
Class 2: Mod­er­ate elec­tro­mag­netic envi­ron­ment. Typ­i­cal envi­ron­ment next to portable trans­mit­ters with power less than 1W. Typ­i­cal house­hold and com­mer­cial envi­ron­ment.
Class 3: Severe elec­tro­mag­netic envi­ron­ment. Typ­i­cal envi­ron­ment where trans­mit­ters with power less than 2W are in use in close prox­im­ity. High power broad­cast trans­mit­ters and ISM equip­ment are in close prox­im­ity. Typ­i­cal indus­trial envi­ron­ment.


Dis­tur­bance injec­tion
Dis­tur­bances are injected using cou­pling decou­pling devices. These devices cou­ple sig­nal to cable with low inser­tion loss and decou­ple dis­tur­bance from aux­il­iary equip­ment. Both devices can be inte­grated in one enclo­sure. Pre­ferred device is CDN– cou­pling decou­pling net­work. Also cur­rent clamp can be used and elec­tro­mag­netic clamp can be used with appro­pri­ate decou­pling net­work.


Dis­tur­bances shall be injected in all cables con­nected to equip­ment under test. In cur­rent case (upper pic­ture) EUT has two cables ant two aux­il­iary equip­ment. In first cable CDN is used for dis­tur­bance injec­tion between EUT and aux­il­iary equip­ment. In sec­ond cable injec­tion clamp is used.

Dur­ing the test­ing only one cable at a time is tested. The fre­quency range is swept from 150kHz to 80MHz, using the sig­nal lev­els estab­lished dur­ing the set­ting process, and with the dis­tur­bance sig­nal 80% ampli­tude mod­u­lated with a 1kHz sine wave, paus­ing to adjust the RF sig­nal level or to change cou­pling devices as nec­es­sary. Where the fre­quency is swept incre­men­tally, the step size shall not exceed 1% of the pre­ced­ing fre­quency value. The dwell time of the ampli­tude mod­u­lated car­rier at each fre­quency shall not be less than the time nec­es­sary for the EUT to be exer­cised and to respond, but shall in no case be less than 0,5s. The sen­si­tive fre­quen­cies (e.g. clock fre­quen­cies or fre­quen­cies iden­ti­fied by the man­u­fac­turer or obtained as out­come of the test) shall be analysed in addi­tion to the stepped fre­quen­cies.

Attempts should be made to fully exer­cise the EUT dur­ing test­ing, and to fully inter­ro­gate all exer­cise modes selected for sus­cep­ti­bil­ity.
The use of a spe­cial exer­cis­ing pro­gram is rec­om­mended.


Per­for­mance cri­te­rion
The tests results are clas­si­fied in terms of loss of func­tion or degra­da­tion of per­for­mance. Inter­na­tional stan­dard EN 61000 – 4-6:2014 does not define Pass/​Fail cri­te­ria. This is defined by generic or spe­cific prod­uct stan­dards. EN 61000 – 4-6:2014 defines per­for­mance cri­te­ria that can be used to eval­u­ate equip­ment under test per­for­mance.

Per­for­mance cri­te­rion A
Nor­mal per­for­mance within lim­its spec­i­fied by the man­u­fac­turer;

Per­for­mance cri­te­rion B
Tem­po­rary loss of func­tion or degra­da­tion of per­for­mance. Self-​recovery after the test, with­out oper­a­tor inter­ven­tion;

Per­for­mance cri­te­rion C
Tem­po­rary loss of func­tion or degra­da­tion of per­for­mance. Oper­a­tor inter­ven­tion needed for recov­ery after the test;

Per­for­mance cri­te­rion D
Loss of func­tion or degra­da­tion of per­for­mance which is not recov­er­able. Dam­age
of hard­ware or soft­ware, or loss of data.


The manufacturer’s spec­i­fi­ca­tion may define effects on the EUT which may be con­sid­ered insignif­i­cant, and there­fore accept­able.

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