## 6 Discussion and Conclusions  
Based on the literature review, modern lighting sources used in commercial and residential facilities can emit significant amounts of conducted emissions at frequencies up to \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \begin{tabular}{c} **Supply** \\ **Voltage [V]** \\ \end{tabular} & **210** & **220** & \
\begin{tabular}{c} **230** \\ **Reference** \\ \end{tabular} & **240** & **250** &
\begin{tabular}{c} **Lighting** \\ **Equipment** \\ \end{tabular} \\ \hline \multirow{4}{*}{\(TSHD\) [dB\({}_{\text{i}}\)V]} & 695.64 & 678.22 & \multirow{4}{*}{635.55} & 637.30 & 582.55 & \multirow{4}{*}{CFL 20 W} \\  & (9.46\%) & (6.71\%) & & (0.28\%) & (\(-\)8.34\%) & \\ \cline{1-1}  & 346.81 & 339.89 & \multirow{4}{*}{343.43} & 341.97 & 337.72 & \multirow{4}{*}{LED 7 W} \\  & (9.99\%) & (\(-\)1.03\%) & & (\(-\)0.42\%) & (\(-\)1.66\%) & \\ \cline{1-1}  & 855.91 & 845.49 & \multirow{4}{*}{840.15} & 81.59 & 825.89 & \multirow{4}{*}{LED 8 W} \\ \cline{1-1}  & (1.88\%) & (0.64\%) & & (\(-\)1.02\%) & (\(-\)1.70\%) & \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Influence of the voltage supply variation on the TSHD index value for EUT. Figure 11: Influence of the voltage supply on the TSHD index value for selected lighting sources. 150 kHz. Currently, existing standards refer to emission limits using nominal parameters of supply, i.e., nominal supply voltage and sinusoidal waveform of supply voltage. However, public power grid regulations permit levels of supply voltage in the range \(\pm\)10% of the rated voltage [14]. It is inclined to propose a discussion-oriented on the new framework of the test conditions, which would consider the impact of voltage supply conditions. The purpose of this paper is to present a methodical and comparative study on the influence of mains voltage level variation on the conducted emission injected into the power grid by selected electrical equipment. With the use of a programmable power supply, the supply voltage sinusoidal shape is maintained at the frequency of 50 Hz, with the only variable being the mains voltage RMS value level. In public low-voltage networks, voltage changes are assumed to be within the permissible range. The measurements are done in a series of steps of 10 V from 210 V to 250 V, respectively. Tested electrical equipment represents popular energy-saving lighting sources using CFL and LED technologies with active and non-active power factor correction. The obtained results lead to the general conclusion that there is a relationship between supply voltage level variations and the low and high frequency conducted emissions introduced into the power grid by electrical loads. In detail, the total harmonic distortion factor increases nearly linearly with an increase in supply voltage in the low-frequency band up to 2 kHz. The increase is mainly influenced by odd harmonics, especially those up to a frequency of approximately 750 Hz (15 th harmonic). In the frequency domain between 9 and 150 kHz, it can be concluded that in the case of LED sources, the amplitude level in the spectra of conducted disturbances is more or less constant at all voltage levels. In contrast, the CFL shows a decrease in the level value of higher frequency conducted disturbances as the supply voltage increases. In comparison to the emission created at the nominal voltage level for the LV network, the maximum conducted emission change for the supply voltage level variation for the study cases is as follows:  
* Higher up to circa 12% in the frequency range 0-2 kHz;
* Higher up to circa 9.5% in the frequency range of 9-150 kHz. In the frequency domain between 9 and 150 kHz, the dependence between the produced emission and mains voltage level variations is unique for each appliance. For two examined types of lighting sources, CFL and LED, it is observed that a change in the supply voltage level causes a shift in the spectrum in the frequency domain.