Harmonics and flicker compliance testing in line with IEC/EN 61000-3-2 and IEC/EN 61000-3-3

Your task

The above-mentioned perturbations lead to thermal stress in grid transformers, voltage fluctuations that damage sensitive components and increased currents in the capacitors of other connected devices. Over time, these effects shorten the lifespan of power equipment and increase the risk of unexpected downtime.

Beyond harmonic interference, voltage fluctuations known as flicker also impact power stability. Flicker is caused by repeated changes in load, such as when starting motors or charging capacitors. These variations can interfere with the performance of nearby electronics and disrupt sensitive operations. Left unmanaged, this instability can damage equipment and compromise the reliability of the surrounding environment.

To ensure market access and operational safety, electronic products must comply with standards such as IEC/EN 61000-3-2/-12 (harmonic current) and IEC/EN 61000-3-3/-11 (voltage flicker).

Rohde & Schwarz solution

The LMG600 power analyzer series provides a turnkey compliance test solution for harmonic current emissions (IEC/EN 61000-3-2) and voltage flicker (IEC/EN 61000-3-3) up to 16 A, integrating a power analyzer, clean AC source and the LMG test suite software. For higher requirements, the system can be extended to support IEC/EN 61000-3-12 and IEC/EN 61000-3-11 tests up to 75 A using additional third-party components. The results are repeatable, traceable and deliver a compliant pass/fail decision from early development through product release.

Harmonics and flicker testing

Harmonics compliance confirms that a product’s input current spectrum stays within defined standard limits. Testing is performed under steady operating conditions using a clean AC source to ensure accuracy. By comparing measured results against standard set values, the process provides a definitive pass/fail decision that secures overall regulatory compliance. This requires certified test equipment and dedicated compliance software.

Flicker compliance testing evaluates voltage fluctuations caused by current variations in the equipment under test (EUT). By applying standardized operating sequences and load steps, the system measures disturbance metrics against established voltage limits. Using a reference impedance source, such as the RI2415 reference impedance for compliance tests in line with IEC/EN 61000-3-3/-11, ensures these measurements are accurate. Together, harmonics and flicker testing confirms that a product behaves as a good grid citizen and does not interfere with the power grid.

LMG test suite software

The LMG test suite works with the LMG600 power analyzer series to perform EMC compliance testing. Measurements are available via real-time online analysis or through stored offline data records. This flexibility extends to hardware compatibility, as the software supports all CE-compliant AC power sources on the market.

The software generates comprehensive PDF test reports, including results and essential electrical properties such as RMS values, power factor and harmonic distortion. These documents feature graphical comparisons of results against standard limits, as well as full documentation of equipment settings and test structures. To eliminate manual post-editing, reports can be customized with company information and design elements for a professional finish.

Supported standards include IEC/EN 61000-3-2/-12 (harmonic emissions) and IEC/EN 61000-3-3/-11 (flicker disturbance). The software also enables standby power measurements (IEC 62301:2011 and EN 50564) and vehicle electromagnetic compatibility testing (ECE R-10.4 Annex 11). The LMG600 series performs harmonic analysis and flicker measurement in line with IEC/EN 61000-4-7 and IEC/EN 61000-4-15. A full list of supported standards can be provided on request.

Application

IEC/EN 61000-3-2 is an international EMC standard that limits harmonic current emissions in low voltage grid systems for EUTs with input currents up to 16 A per phase. This standard is used in the measurement example below.

Before starting the test, the EUT is supplied with a nearly sinusoidal voltage using a clean AC power source that is suited for harmonics compliance testing. To avoid interference with other measurements, any signal cables from the LMG600 power analyzer series should be disconnected before starting to wire the test setup. Also, it should be ensured that the test environment meets the IEC/EN 61000-4-7 requirements as indicated in the standard description (IEC 61000-4-7:2002).

Measurement circuit

The measurement circuit for a 3-phase EUT in line with IEC/EN 61000-3-2 is as shown in the figure below. For single-phase measurements, the same circuit applies by ignoring two of the three phases. In the software, operation of a 1- or 3-phase EUT is clearly selectable in the test parameters (see screenshot second image).

The EUT analyzed in this example is single-phase and the circuit diagram used is displayed in the next figure. The same circuit applies for the IEC/EN 61000-3-12 standard in both cases.

If a flicker measurement is to be analyzed, the circuit diagram in the following figure shows the circuit necessary for the EN/IEC 61000-3-3 standard. Although the example focuses on harmonic compliance, flicker analysis would follow similar steps. It is important to recall that a network impedance will be required additionally for such a test, as mentioned in the flicker testing section.

Measurement steps

1. If an AC power supply is not used, plug the EUT power supply into the LMG-MAS breakout box for Schuko devices or another suitable Schuko adapter
2. Connect the LMG-MAS to CH1 of the power analyzer using laboratory leads
3. Open the LMG test suite software
4. Press Test in the Quick Access Bar at the top of the main screen
5. In the test description:
– Select the measuring standard EN 61000-4-7:2002 +A1:2009
– Select limits as EN 61000-3-2:2014
– Select normal test conditions
6. Select the correct device class
7. Set the expected power consumption for the EUT and any additional information needed
8. Set the correct mains voltage and mains frequency (manually or automatically by selected region)
9. If EUT specific information is needed in the report, this can be added under EUT details, test equipment, laboratory details, product mode details and instrumentation details
10. Click OK
11. Press Connect to connect an LMG600 for the first time, or it connects automatically if the LMG600 is recognized
12. Select the channel connected to the EUT
13. Click OK
14. The software requires the EUT to be in a mode expected to produce the maximum total harmonic current and gives you the opportunity to check this graphically
15. Press Start Measure
16. The results, including minimum and maximum values, are clearly displayed after the measurement

Test report interpretation

After a successful test, a comprehensive report is generated, including detailed harmonic distortion percentages for review. The test report can be exported in different formats (e.g. .pdf, .docx and .csv). An example report is shown below.

If a test fails, the LMG test suite software provides a detailed analysis of the non-compliant results and the exact harmonic levels at which the failure occurred. This precise data accelerates the selection of appropriate power factor correction (PFC) circuits or special filters, reducing overall product development time.

Summary

The LMG600 power analyzer series provides turnkey compliance testing for EMC standards. It supports harmonic current emissions (IEC/EN 61000-3-2) and voltage flicker (IEC/EN 61000-3-3) testing up to 16 A (expandable to 75 A). The combination of a power analyzer and a clean AC power source delivers accurate pass/fail decisions about power grid compliance of the EUT.

The LMG test suite software automates measurements and generates detailed PDF reports, including RMS values and harmonic distortion orders. Precise analysis of failed tests enables rapid optimization of filters and PFC measures, accelerating product release.