## 4 Application Example
### Energy Study of the Transformation House  
The Fluke 435 Series II analyzer was connected to the transformer secondary terminals and measurements were made on working days and holidays. The values of the transformer copper losses, due to each component of the secondary currents, were measured by the Fluke 435 Series II analyzer, entering in the loss screen of this instrument (Figure 3) a value of resistance equal to the short-circuit resistance of the transformer, indicated in Table 4.  
The active (\(P\)) and reactive (\(Q^{\prime}\)) powers recorded throughout the measurement campaign on working days and holidays remained (without significant changes) at the values represented in Figures 4 and 5, for working days and holidays, respectively. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Rated Power (kVA)** & **Copper Losses (W)** & **Core losses** & **Short-Circuit** \\  & & **(W)** & **Resistance (\(\Omega\))** \\ \hline
1600 & 17,000 & 2600 & 0.011708 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Nominal features of Ormazabal distribution transformers. Figure 3: Loss calculator screen from the analyzer Fluke 435 Series II. Based on the measured values of reactive power (\(Q^{\prime}\)), represented in Figures 4 and 5, it was deduced that the capacitor banks (\(Q_{c1}\) and \(Q_{c2}\)) were permanently connected at all hours of working days and holidays, giving rise to the high values of capacitive reactive power (higher than 300 kVAr) during times of low activity of companies. The values of the reactive power absorbed by the installations fed by the transformer, without the effect of the capacitor banks, are those represented by \(Q\) in Figures 4 and 5. The values of the transformer copper losses, due to the active and reactive currents (\(P_{ca}\) and \(P_{cr}^{\prime}\)), are those represented in Figures 6 and 7, for working days and holidays, respectively. Likewise, these figures represent the losses that the reactive currents would cause if the capacitor banks (\(P_{cr}\)) were not connected. The comparison of the values of \(P_{cr}\) and \(P_{cr}^{\prime}\) shows the impact produced by the capacitor banks on the copper losses of the transformer, which are especially important in periods of low activity of the companies. It can be noted in Figures 6 and 7 that transformer power losses caused by reactive currents have values between 500 and 700 W each hour in low activity periods, with capacitor banks, whereas these power losses reach only between 50 and 100 W each hour in these periods if capacitor banks were disconnected. Figure 4: Active (\(P\)) and reactive (\(Q^{\prime}\)) powers delivered by the transformer on working days, as well as the reactive powers (\(Q\)) supplied without capacitor banks. (Negative sign indicates capacitive reactive powers). Figure 5: Active (\(P\)) and reactive (\(Q^{\prime}\)) powers delivered by the transformer during holidays, as well as the reactive powers (\(Q\)) supplied without capacitor banks. (Negative sign indicates capacitive reactive powers). Likewise, the Fluke 435 Series II analyzer recorded the values of copper losses caused in the transformer by unbalanced currents (\(P_{cu}\)) and distortion currents (\(P_{ch}\)). These values are those indicated in Figures 8 and 9, for working days and holidays, respectively. It can be seen in these figures that the copper losses caused by the distortions were greater than those caused by the unbalances, undoubtedly due to the amplification of the distortion currents produced by the Ferranti effect in the presence of capacitive loads. However, the importance of losses due to imbalances and distortions is comparatively much less than those caused by capacitive reactive currents. Figure 6: Transformer power losses in working days due to (a) active currents (\(P_{ca}\)); (b) reactive currents with capacitors (\(P_{cr}\)); and (c) reactive currents without capacitors (\(P_{cr}\)).