The four common EMC standards for lighting are CISPR 15, IEC 61547, IEC 61000-3-2 and IEC 61000-3-3. CISPR 15 and IEC 61547 requires radiated tests related to anechoic chamber.

EMC tests for lighting equipments

On this page we are focusing on the tests which require anechoic chambers. Let’s start with CISPR 15 and Radiated Emissions.

1) Anechoic Chamber requirements according to CISPR 15

CISPR 15 requires radiated emissions tests for the frequency range 30MHz to 1GHz. The standard lists alternative test methods for the radiated emissions tests: OATS/SAC at 10m, OATS/SAC at 3m, FAR at 3m, TEM-Waveguide and CDNE. For full compliance testing you should choose one of them. Anechoic Chamber related test methods require one of these test chambers:

1. Semi Anechoic Chamber (SAC) for 10m measurements
2. Semi Anechoic Chamber (SAC) for 3m measurements
3. Fully Anechoic Room (FAR) for 3m measurements

Since CISPR 15 requires radiated emissions tests to be performed according to CISPR 16-2-3, the anechoic chamber requirements are on CISPR 16-2-3 and CISPR 16-1-4.

Typical FAR site geometry is given on Figure 12 of CISPR 16-2-3:2016+AMD1:2019:

2) Anechoic Chamber requirements according to IEC 61547

IEC 61547 requires Radio-Frequency Electromagnetic Fields immunity tests for the frequency range 80MHz to 1GHz. This test shall be performed according to the IEC 61000-4-3 standard. Thus for full compliance testing, the anechoic chamber to be used shall comply with the requirements (field uniformity) of IEC 61000-4-3.

IEC 61547 requires Radio-frequency electromagnetic fields tests require to generate field with these parameters:

Frequency range : 80-1000 MHz

Field level: 3V/m (unmodulated)

Modulation: 1 kHz, 80 % AM, sine wave

The anechoic chamber’s field uniformity performance shall cover above frequency range and field level.  

IEC 61000-4-3 requirements

IEC 61000-4-3:2020 lists the anechoic chamber requirements under its Description of the test facility article:

‘’Because of the magnitude of the field strengths generated, the tests shall be made in a shielded enclosure in order to comply with various national and international laws prohibiting interference with radio communications. In addition, since most test equipment used to collect data is sensitive to the electromagnetic field generated during the execution of the immunity test, the shielded enclosure provides the necessary “barrier” between the EUT and the required test instrumentation. Care shall be taken to ensure that the interconnection wiring penetrating the shielded enclosure is adequately isolated from the conducted and radiated emission and preserves the integrity of the EUT signal and power responses.

The test facility typically consists of an absorber-lined shielded enclosure large enough to accommodate the EUT whilst allowing adequate control over the field strengths. This includes

anechoic chambers or modified semi-anechoic chambers, an example of which is shown in Figure 2. Associated shielded enclosures should accommodate the field generating and

monitoring equipment, and the equipment which exercises the EUT.’’

16-point Uniform Field Area (1.5×1.5m) or field uniformity performance is measured to ensure the test facility’s compliance to IEC 61000-4-3. It is used to demonstrate the capability of the test facility and the test equipment to generate the uniform field for testing. Data for setting the required field strength for the immunity test is obtained and is used to test all EUTs.

Field Uniformity measurements of an EMC anechoic chamber can be done by the laboratory itself or third party calibration or test site validation service providers. Internal measurements need expertise and additional tools for validation setup. Third party calibration or validation shows independency since the validation is not performed by the chamber installers or the chamber’s owner.

IEC 61547 does not specifically require a Fully Anechoic Room (FAR) or Semi Anechoic Chamber (SAC) and it refers to IEC 61000-4-3 for chamber related requirements. Thus, Radio-Frequency Electromagnetic Fields immunity tests according IEC 61547 can be done in 

1. Semi Anechoic Chamber (SAC) for 3m measurements (this may require additional RF absorbers for the floor to reduce reflections)
2. Fully Anechoic Room (FAR) for 3m measurements

Summary – Anechoic Chamber requirements according to CISPR 15 & IEC 61547

Considering the anechoic chamber requirements of both CISPR 15 and IEC 61547 any of these two chamber types can be used for Radiated Emissions (RE) and Radiated Immunity (RI) tests:

Radiated Emissions test setups have some differences when SAC and FAR is compared. Since SAC requires antenna scanning between 1 and 4 meter heights, antenna mast is needed. However FAR does not require such a scanning, a fixed position of the antenna is enough.  The antenna inside a FAR shall be located at middle level of the test volume. Important requirement for FAR: the turntable, antenna mast and supporting floor shall be in place during the site validation procedure.

Radiated Immunity test setups are almost similar when SAC and FAR compared. Adding floor RF absorbers (ferrite tiles) to SAC would allow it be like FAR. 

Differences:

1) Dimensions: SAC has larger dimensions like 9x6x6m, FAR can be smaller since there is no requirement about the height and the only requirement is NSA and Field Uniformity performance. 

2) Floor: SAC has a ground floor. Removable RF absorbers allow the chamber switch between RE and RI test setups. While performing RE tests, floor shall remain ground. While performing RI tests, floor might be covered with portable RF absorbers. 

3) Price: Due to dimensions SAC would be more expensive than FAR. 

4) Advantages: Due to larger dimensions, with SAC electronic products other than lighting products can also be tested.  Electronic products other than lighting which require 1-4m antenna scanning during radiated emissions tests cannot be tested in FAR if its height is does not cover this scanning range. 

Recommendations:

If you would like to perform the tests only for lighting equipments, FAR is recommended. You can both perform RE and RI tests compliant with the standards inside the fully compliant FAR. It is an economical solution for the organizations who are only focusing on EMC testing of lighting equipments. 

If you would like to perform several electronic products including lighting equipments, SAC with additinoal RF absorbers is recommended. This option will allow you to switch the chamber between SAC and FAR by using additional movable ferrite tiles on the floor. Even it is costly, it is recommened as long term solution. 

What we offer:

We are offering any test site solution related to lighting EMC. Design to on-site installation services of semi anechoic chamber or fully anechoic room. We can add any EMC test instrument to offer a turnkey solution. Onsite training and site validation services are also available.