# Power Quality Impact and Its Assessment: A Review and a Survey of Lithuanian Industrial Companies
## 5 Discussion
### Further Analysis of the Survey Results: PQ Impact Similarity Assessment  
In this section, possibilities of further analysis of the survey results will be demonstrated. The task is to perform a comparison in order to assess the similarly of the impact of RMS voltage variations on different end-use devices. A qualitative comparison will be  
Figure 11: The Johari window. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Aspect** & \multicolumn{4}{c}{**Evaluation of Competence**} \\  & **I** & **II** & **III** & **IV** \\ \hline Knowledge of LST EN 50160:2010 & - & 0.50 & 0.50 & - \\ Familiarity with other PQ standards & 1.00 & - & - & - \\ Familiarity with the relevant EMC standards & 1.00 & - & - & - \\ Experience in PQ data analysis & - & 0.75 & 0.25 & - \\ Selection of internal monitoring nodes & - & 0.50 & 0.50 & - \\ Experience in remote PQ monitoring & 1.00 & - & - & - \\ Short-duration RMS variation mitigation & - & 1.00 & - & - \\ Harmonic mitigation & - & 1.00 & - & - \\ Voltage transient mitigation & 1.00 & - & - & - \\ Realization of predictive maintenance & 1.00 & - & - & - \\ Assessment of economic losses & - & 0.50 & 0.50 & - \\ \hline \hline \end{tabular}
\end{table} 
Table 32: Competency evaluation of the Lithuanian industry in the field of PQ. performer first, followed by a quantitative comparison. The methodology is described in Sections 3.2 and 3.3. The comparative samples with relevant statistical parameters are listed in Table 33. The smallest sample size is 7, the largest is 46. The numbers assigned to the categories in the table will continue to be used in this work. As mentioned in Section 3, the scores are expressed as a percentage, thus the maximum value is 100, and the minimum value is 0. The samples with a size of either 1 or 2 will not be further investigated. Nevertheless, they are important for further research (e.g., end-user equipment classification) and for the general understanding of the influence of PQ on technological processes. The type of one-tailed test in each case is given in Table 34: the \(z\)-test is used six times, and the \(t\)-test is used in the rest of the cases. The calculated scores are given in Tables 35-37. The critical values are given in Appendix A. Obviously, the table is symmetrical with respect to the main diagonal. There are 36 tests in total. The core part of the tests is based on Equation (23). The total number of the positive decisions on the similarity are presented in Tables 38-40: Table 38 presents the results when the significance level is 0.05, Table 39--when the significance level is 0.10, and Table 40--the total sum of the numbers given in Tables 38 and 39. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{**No.**} & \multirow{2}{*}{**Category**} & \multirow{2}{*}{**Size**} & \multicolumn{2}{c}{**Mean**} & \multicolumn{3}{c}{**Population**} & \multicolumn{3}{c}{**Sample**} \\  & & & **1** & **2a** & **2b** & **1** & **2a** & **2b** & **1** & **2a** & **2b** \\ \hline
1. & Controllers & 46 & 80.22 & 90.71 & 90.61 & 16.94 & 13.52 & 13.67 & 17.12 & 13.57 & 13.72 \\
2. & LV three-phase & 44 & 76.05 & 88.00 & 87.88 & 21.09 & 17.46 & 17.56 & 21.33 & 17.66 & 17.76 \\
3. & Lighting & 33 & 48.30 & 65.33 & 65.00 & 25.83 & 25.26 & 25.44 & 26.24 & 25.65 & 25.84 \\
4. & Heating elements & 30 & 42.73 & 59.86 & 59.40 & 27.83 & 24.97 & 25.17 & 28.31 & 25.40 & 25.60 \\
5. & LV single-phase & 27 & 66.52 & 79.58 & 79.38 & 28.02 & 23.81 & 24.00 & 28.55 & 24.27 & 24.46 \\
6. & Servers & 18 & 72.00 & 83.01 & 82.80 & 29.66 & 23.62 & 23.88 & 30.52 & 24.31 & 24.57 \\
7. & MV three-phase & 11 & 80.73 & 89.56 & 89.47 & 23.76 & 20.42 & 20.52 & 24.92 & 21.42 & 21.52 \\
8. & Variable-frequency drives & 9 & 80.67 & 91.50 & 91.38 & 18.40 & 13.24 & 13.49 & 19.52 & 14.05 & 14.30 \\
9. & Welding equipment & 7 & 47.71 & 64.72 & 64.20 & 31.56 & 27.05 & 27.43 & 34.09 & 29.21 & 29.62 \\ \hline \hline \end{tabular}
\end{table} 
Table 33: Statistical parameters of the comparative samples.