# Smart Internet of Things Power Meter for Industrial and Domestic Applications
## 4 Results
### Numerical Results  
The measurement errors between the devices for each electrical property are displayed in Table 2. Columns 2 to 4 presents the error between our meter and each industrial meter, and the average value of the three errors is calculated in the last column. The last line of the table presents the average of all electrical properties' error values, which can be interpreted as general error values. Figure 6: Power meters cabinet. For a clearer analysis, we also compared the values measured by the industrial meters and determined the measurement errors between them using (_7_). \[Err_{X-Y}[\%]=\frac{PMX_{value}-PMY_{value}}{PMY_{value}}\times 100\% \tag{7}\] \[ArgErr_{XY}[\%]=\frac{Err_{X-Y}+Err_{Y-X}}{2}\]  
where  
\(PMX_{value}\) and \(PMY_{value}\) are the values measured by different meters (\(X\) and \(Y\)), \(Err_{X-Y}\) is the measurement error between meter \(X\) and meter \(Y\) (reference), \(AvgErr_{XY}\) represents the average measurement error between two different meters. Table 3 presents the industrial meters' comparative errors in columns 2 to 7. As can be seen, each device was taken sequentially as a reference for the other meters. Finally, the average error values between each pair of devices are calculated in the last row of the table. From these results, we can observe that our device most closely aligns with the values measured by the Siemens SENTRON PAC4200 meter (0.92% error), which was expected given the fact that it was calibrated against it. We can also see that the Phoenix Contact meter presents the largest errors compared to the Siemens (2.82%) and Janitza (3.39%) meters, explaining why our power meter has the largest measurement error against this device (3.06%). The largest errors of our device can be observed in the case of THD measurements. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Measurement**} & \multicolumn{4}{c}{**Measurement Error [\%]**} \\ \cline{2-5}  & **Janitza** & **Phoenix** & **Siemens** & **Average** \\  & **UMG-96 RM** & **EEM-MA400** & **PAC4200** & **Average** \\ \hline Voltage & 0.24 & 0.24 & 0.09 & 0.19 \\ Current & 0.14 & 0.59 & 0.44 & 0.30 \\ Frequency & 0.02 & 0.02 & 0.02 & 0.02 \\ Power Factor & 0.02 & 0.02 & 0.02 & 0.02 \\ Active Power & 0.37 & 0.74 & 0.36 & 0.24 \\ Reactive Power & 2.27 & 9.36 & 1.09 & 2.16 \\ Apparent Power & 0.38 & 0.73 & 0.36 & 0.27 \\ Voltage THD & 4.38 & 8.07 & 3.10 & 4.03 \\ Current THD & 5.08 & 7.75 & 2.85 & 3.79 \\
**Average** & **1.43** & **3.06** & **0.92** & **1.22** \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Power meter (our solution) vs. industrial meter measurement errors. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Measurement**} & \multicolumn{4}{c}{**Measurement Error [\%]**} \\ \cline{2-5}  & **JAN vs. PHX** & **PHX vs. JAN** & **JAN vs. SIM** & **SIM vs. JAN** & **PHX vs. SIM** & **SIM vs. PHX** \\ \hline Voltage & 0.03 & 0.03 & 0.16 & 0.16 & 0.16 & 0.16 \\ Current & 0.73 & 0.72 & 0.57 & 0.57 & 0.15 & 0.15 \\ Frequency & 0.01 & 0.01 & 0.01 & 0.01 & 0.02 & 0.02 \\ Power Factor & 0.01 & 0.01 & 0.01 & 0.01 & 0.02 & 0.02 \\ Reactive Power & 11.89 & 10.57 & 3.06 & 2.98 & 8.50 & 9.36 \\ Apparent & 1.12 & 1.11 & 0.74 & 0.73 & 0.38 & 0.38 \\ Power & 7.74 & 7.78 & 1.59 & 1.62 & 7.45 & 7.62 \\ Voltage THD & 8.26 & 8.72 & 2.50 & 2.58 & 7.84 & 7.77 \\ \hline \multirow{2}{*}{Average} & 3.43 & 3.34 & 1.04 & 1.04 & 2.77 & 2.87 \\  & 3.39 & & 1.04 & & 2.82 \\ \multicolumn{2}{c}{JAN-PHX} & \multicolumn{2}{c}{JAN-SIM} & \multicolumn{2}{c}{PHX-SIM} \\ \hline \hline \end{tabular}
\begin{tabular}{c} JAN = Janitza UMG-96 RM meter, PHX = Phoenix Contact EEM-MA400 meter, SIM = Siemens SENTRON PAC4200 meter.  
\end{table} 
Table 3: Industrial meters comparative measurement error. They are a result of the FFT library harmonics amplitude estimation accuracy and can be improved by calibrating the voltage and current harmonic measurements with the reference meter's values.