Conducted Immunity IEC 61000-4-6. What exactly does conducted immunity mean? It is a test to determine overall immunity to radiated fields, but the test.

ConductedConducted Immunity Immunity

IEC 61000-4-6IEC 61000-4-6

What exactly does “conducted What exactly does “conducted immunity” mean?immunity” mean?

It is a test to determine overall immunity to radiated It is a test to determine overall immunity to radiated fields, but the test is performed with signals injected onto fields, but the test is performed with signals injected onto cables, ie: “conducted” into the EUT. cables, ie: “conducted” into the EUT.

If the EUT is small relative to the wavelength, the If the EUT is small relative to the wavelength, the interfering signal will not significantly excite the EUT interfering signal will not significantly excite the EUT itself, but the connected cables will act as antennae and itself, but the connected cables will act as antennae and can become resonant. The signal will then conduct into can become resonant. The signal will then conduct into the EUT through the ports.the EUT through the ports.

Why not radiate?Why not radiate?

Creating fields this low in frequency require a large Creating fields this low in frequency require a large antenna and amplifier. $$$$$$$antenna and amplifier. $$$$$$$

At the practical EUT-antenna distances involved, will be At the practical EUT-antenna distances involved, will be operating in the near field. Predictability of coupling to operating in the near field. Predictability of coupling to the EUT is poor.the EUT is poor.

Advantages (over radiated test)Advantages (over radiated test)Requires significantly less amplifier.Requires significantly less amplifier.

Does not require anechoic chamber.Does not require anechoic chamber.

Typical test setups cost less.Typical test setups cost less.

More repeatable.More repeatable.

Testing ports individually aids in mitigation. Testing ports individually aids in mitigation. “Which port is susceptible??”“Which port is susceptible??”

DisadvantagesDisadvantages

With many ports, can be more time consuming.With many ports, can be more time consuming.

Multiple ports require multiple CDNS. Multiple ports require multiple CDNS.

Can only approximate real world situations (all Can only approximate real world situations (all cables exposed).cables exposed).

IEC 61000-4-6IEC 61000-4-6

Testing and measurement techniques – Immunity to Testing and measurement techniques – Immunity to conducted disturbances induced by radio-frequency conducted disturbances induced by radio-frequency fields.fields.

Scope: Immunity requirements of electrical and electronic Scope: Immunity requirements of electrical and electronic equipment to electromagnetic disturbances coming from equipment to electromagnetic disturbances coming from intended radio-frequency transmitters in the frequency range of intended radio-frequency transmitters in the frequency range of 9kHz to 80 MHz. Equipment not having at least one conducting 9kHz to 80 MHz. Equipment not having at least one conducting cable is excluded.cable is excluded.

Object: Establish a common reference for evaluating the Object: Establish a common reference for evaluating the functional immunity of equipment when subjected to conducted functional immunity of equipment when subjected to conducted disturbances.disturbances.

Frequency Breakpoint, Frequency Breakpoint, Radiated vs ConductedRadiated vs Conducted

Basic standard is 80 MHz.Basic standard is 80 MHz.

Some product family standards extend this to Some product family standards extend this to 230 MHz.230 MHz.

Limitations of CDNs with regards to impedance Limitations of CDNs with regards to impedance and decoupling requirements.and decoupling requirements.

Why 80MHz instead of 30MHz Why 80MHz instead of 30MHz (emissions breakpoint)?(emissions breakpoint)?

Efficiency of antenna at low frequencies more Efficiency of antenna at low frequencies more critical in immunity.critical in immunity.

Range up to 80MHz easily accomplished by Range up to 80MHz easily accomplished by CDNs.CDNs.

Radiated Emissions easily performed at farther Radiated Emissions easily performed at farther distances, while radiated immunity power distances, while radiated immunity power requirements prohibit testing farther than 3m. requirements prohibit testing farther than 3m.

Test Levels:Test Levels:

Specified as open-circuit voltage (emf)Specified as open-circuit voltage (emf)

120dBuV or 1V.120dBuV or 1V. 130dBuV or 3V. (note: 3V = 129.5dBuV)130dBuV or 3V. (note: 3V = 129.5dBuV) 140dBuV or 10V140dBuV or 10V X – open levelX – open level 80% amplitude modulated with 1kHz modulation 80% amplitude modulated with 1kHz modulation

frequency.frequency.

EquipmentEquipment

RF GeneratorRF Generator

– Signal generatorSignal generator

– AmplifierAmplifier

– AttenuatorAttenuator

– Specific requirements regarding harmonics.Specific requirements regarding harmonics.

Coupling and decoupling Coupling and decoupling device(s).device(s).

CDN (preferred)CDN (preferred)– Specific requirement for impedance Specific requirement for impedance

(nominal 150 ohm).(nominal 150 ohm).

Clamp injection devicesClamp injection devicesImpedance and decoupling established at the AE Impedance and decoupling established at the AE device.device.

– EM ClampEM Clamp– Bulk Current Injection (BCI) probe.Bulk Current Injection (BCI) probe.

Direct injection devicesDirect injection devices150 to 50 ohm adapters150 to 50 ohm adapters

Level Setting (calibration) Level Setting (calibration) procedureprocedure

Actual voltage level is half the test specification. Actual voltage level is half the test specification.

In 150 ohm system, measured level is 1/6 the In 150 ohm system, measured level is 1/6 the test specification. In a 50 ohm system, the test specification. In a 50 ohm system, the measured level is ½.measured level is ½.

Test setupTest setup

EUT 0.1m above ground reference plane.EUT 0.1m above ground reference plane.Interconnecting cables 30 to 50mm above GRP.Interconnecting cables 30 to 50mm above GRP.CDNs 0.1 to 0.3m from the projection of the EUT onto CDNs 0.1 to 0.3m from the projection of the EUT onto the reference plane.the reference plane.Rules for selecting the injection method. (see 7.1.1) Rules for selecting the injection method. (see 7.1.1) CDNs are preferred.CDNs are preferred.Only two CDNs Only two CDNs requiredrequired. One has the signal injected, . One has the signal injected, the other is terminated, providing a 150 ohm impedance.the other is terminated, providing a 150 ohm impedance.Selection of which port to terminate. (See 7.2) Pick the Selection of which port to terminate. (See 7.2) Pick the port with the lowest circuit impedance.port with the lowest circuit impedance.If clamp injection is used, must adhere to sections 7.3 or If clamp injection is used, must adhere to sections 7.3 or 7.4. Emphasis is on maintaining a 150 ohm circuit 7.4. Emphasis is on maintaining a 150 ohm circuit impedance. If not, procedure in 7.4 is used.impedance. If not, procedure in 7.4 is used.

Test ProcedureTest Procedure

Swept from 150kHz to 80MHzSwept from 150kHz to 80MHz

Dwell time with AM carrier at each Dwell time with AM carrier at each frequency long enough for EUT to be frequency long enough for EUT to be exercised and respond, but no less than exercised and respond, but no less than 0.5 seconds.0.5 seconds.

Provisions for frequency switching Provisions for frequency switching transients. Level may be reduced during transients. Level may be reduced during frequency steps. (new)frequency steps. (new)

Evaluation of results.Evaluation of results.

A.A. Normal performance.Normal performance.

B.B. Temporary loss of function, which Temporary loss of function, which ceases after disturbance ceases without ceases after disturbance ceases without intervention.intervention.

C.C. Temporary loss of function, requires Temporary loss of function, requires intervention.intervention.

D.D. Loss of function which is not recoverable.Loss of function which is not recoverable.

Test report.Test report.

Includes all information necessary to Includes all information necessary to reproduce test.reproduce test.

Description of EUT exercising method.Description of EUT exercising method.

Performance level specified by Performance level specified by manufacturer.manufacturer.

Observed effects of disturbance.Observed effects of disturbance.

Rationale for pass/fail.Rationale for pass/fail.

Changes from edition 1.1 to 2.2Changes from edition 1.1 to 2.2

Only two 150 ohm connections: The source Only two 150 ohm connections: The source CDN, and one terminated CDN. CDN, and one terminated CDN.

1% step size, dwell time long enough for EUT to 1% step size, dwell time long enough for EUT to be exercised and respond, but no less than 0.5 be exercised and respond, but no less than 0.5 seconds. seconds.

CDNs are now “preferred” in the text of the CDNs are now “preferred” in the text of the standard. (6.2)standard. (6.2)

Impedance requirements for 80 to 230 MHz now Impedance requirements for 80 to 230 MHz now specified, with more tolerance. (B.1)specified, with more tolerance. (B.1)

Changes, cont’dChanges, cont’d

The modulation check (6.4) no longer specifies that an The modulation check (6.4) no longer specifies that an RF oscilloscope must be used.RF oscilloscope must be used.

The output level can be determined either by measuring The output level can be determined either by measuring the power from the amp output, or by the signal the power from the amp output, or by the signal generator output – as long as the stability of the system generator output – as long as the stability of the system can be guaranteed. (6.4) This was not mentioned in ed can be guaranteed. (6.4) This was not mentioned in ed 1.1.1.1.

Ed 1.1 stated that the modulation must remain switched Ed 1.1 stated that the modulation must remain switched on. (6.4) This requirement has been removed. on. (6.4) This requirement has been removed.

Several drawings changed, to reflect more attention Several drawings changed, to reflect more attention given to maintaining AE impedance.given to maintaining AE impedance.

Annex F, Test setup for large EUTs.Annex F, Test setup for large EUTs.

Comments, ObservationsComments, Observations

Verify CDNs in-house if possible. Verify CDNs in-house if possible.

Why open-circuit voltage spec?Why open-circuit voltage spec?

Current formula in 7.4 – is it correct, or will the Current formula in 7.4 – is it correct, or will the EUT be overtested? This seems to conflict with EUT be overtested? This seems to conflict with 6.2.2. By the equation, the EUT could be 6.2.2. By the equation, the EUT could be overtested.overtested.

““Overtesting” depends on whether the Overtesting” depends on whether the susceptible circuit is capacitively or inductively susceptible circuit is capacitively or inductively coupled.coupled.

Comments, Observations, cont’dComments, Observations, cont’d

No specific requirements to check linearity or gain No specific requirements to check linearity or gain compression, only a mention of checking modulation compression, only a mention of checking modulation envelope. (see 6.4) 61000-4-3 calibrates to 1.8 times envelope. (see 6.4) 61000-4-3 calibrates to 1.8 times the level.the level.

Harmonics should be checked at 1.8 times the test level Harmonics should be checked at 1.8 times the test level (peak modulation envelope).(peak modulation envelope).

When testing to 7.4, “The modified test voltage level When testing to 7.4, “The modified test voltage level shall be recorded in the test report”. How do you shall be recorded in the test report”. How do you determine the test voltage from the current, when the determine the test voltage from the current, when the circuit impedance is unknown? Assume 150 ohms?circuit impedance is unknown? Assume 150 ohms?

Problems with Annex F, Test setup Problems with Annex F, Test setup for large EUTs.for large EUTs.

Two ground planes, separated by a protective Two ground planes, separated by a protective earth conductor. Resonance?earth conductor. Resonance?

EUT relationship to the ground plane not defined EUT relationship to the ground plane not defined adequately. No mention of 10cm distance from adequately. No mention of 10cm distance from ground plane as there is for standard orientation.ground plane as there is for standard orientation.