When it comes to lighting installations, the European directive 2014/30/EU (EMC directive) refers, among other things, to the harmonised European standard EN 55015 "Limits and methods of measurement of radio disturbance characteristics of electrical lighting and similar equipment". Interference emission thresholds in a frequency range above 9 kHz as well as measuring methods for compliance testing are specified in this standard. Currently, permissible interference levels are established up to a frequency of 300 MHz. An expansion of the standard regarding testing and evaluation of interference field intensities going up to 1,000 MHz is currently in process. The established thresholds apply for conducted as well as radiated high-frequency interference emanating from luminaires and luminaire accessories.
Luminaires for incandescent lamps which do not contain light control devices or electronic circuits do not generate electromagnetic interference and are therefore exempt from EMC testing.
All luminaires – with the exception of incandescent lamp luminaires – must comply with thresholds regarding interference potential at their mains voltage supply connection terminals as well as other electrical lines. Figure displays maximum permissible interference potential quasi peak values QS and averages M in relation to frequency. These values also apply to dimmers and transformers with semiconductors.
EN 55015 determines thresholds for the magnetic component of the (wirelessly emitted electromagnetic) interference field intensity (see figure) with thresholds varying depending on the diameter of the testing antenna to be arranged around the luminaire.
Particular applications, e.g. in military contexts or in airfield lighting, can be subject to advanced requirements regarding the limitation of interference emissions.
To ensure a lighting installation’s electromagnetic compatibility, it is necessary to consider the installed luminaires as functional units, i.e. not just their individual components. Even when only control gear and other control components compliant with standard EN 55015 are used, circuit design must be carried out diligently – especially regarding wiring inside of luminaires – in order for the luminaire as a functional unit to comply with EN 55015 requirements as well. In isolated cases, additional interference suppression components may be necessary if the occurring interference emissions cannot be sufficiently reduced through construction measures (see figure).
In practice, even despite diligent electromagnetic compatibility testing, interference e.g. in radio reception or radio transmission can occur during luminaire operation in isolated cases. This is the case in connection with adverse operating conditions. In some cases, interference of this nature can be sufficiently reduced by using a braid-breaker (ferrite bead, see figure) which encircles the voltage supply line.