# Evaluating Effects of Electric Vehicle Chargers on Residential Power Infrastructure
## 3 Load Profile Analysis of EV Chargers
### Voltage and Current Analysis  
Current and voltage are basic parameters used to analyze the behavior of various electrical loads, enabling more efficient system planning and design. Identifying problems such as current overload can prevent damage to connected devices, and voltage monitoring can prevent abnormal operations, allowing the original system to be expanded to support the use of chargers. Figure 4 shows a voltage profile graph comparing the average voltage reading (V\({}_{\text{avg}}\)) with the graph state at each time point for the three phases (V\({}_{1}\), V\({}_{2}\), and V\({}_{3}\)). An analysis of the average voltage readings (V\({}_{1,\text{avg}}\), V\({}_{2,\text{avg}}\), and V\({}_{3,\text{avg}}\)) collected from EV chargers in condominium is presented. The blue background represents the time periods when there are active electric vehicle charging users. This graph provides insights into the load profile and potential problems within the power system. The graph shows the change in the average voltage over time for the three phases, indicating how the electrical load varies throughout the data collection period. The voltage values of all three phases generally show a consistent pattern. However, some anomalies can be observed, including periods when the voltage drops significantly, sometimes reaching zero volts, especially in V\({}_{1}\) and V\({}_{2}\). There are also cases where the voltage value rises above the normal range. Such fluctuations indicate that the electrical load may be imbalanced or that there may be issues with the charger. Figure 5 illustrates the maximum current of each phase (I\({}_{1,\text{Max}}\), I\({}_{2,\text{Max}}\), and I\({}_{3,\text{Max}}\)) compared with the charging state at each time point. It was found that, during charging periods, the maximum current of each phase is significantly higher, especially in 1-Phase (I\({}_{1,\text{Max}}\)), indicating higher energy usage to charge EVs. During non-charging periods, the peak current of each phase is greatly reduced, indicating lower power consumption. The analysis also revealed that the increase in current during the charging time is directly related to the number and timing of EVs being charged, as shown in the graph depicting the increase in current during continuous charging. This graph shows that there is a higher demand for single-phase charging services than for three-phase charging services. As a result, the current in 1-Phase is higher than in the other phases. It can be observed that significantly higher currents in Phases 2 and 3 occur at certain times, coinciding with specific charging behaviors. This indicates an imbalanced load distribution between the different phases, which may impact power quality, such as causing harmonic and voltage distortion. During non-charging periods, the maximum current of all phases is very low, indicating minimal or no power consumption during those times. This is consistent with predictions that, when EVs are not being charged, electrical energy use returns to normal levels without affecting the electrical system. This analysis also shows that, during non-charging periods, the electrical system can return to a stable state without stressing the electrical equipment, helping to reduce the risk of electrical problems and maintenance requirements. From the analyzed data, it was found that, during EV charging periods, the peak current of each phase increases significantly, causing stress on electrical equipment such as  
Figure 4: Voltage profiles of all three phases in relation to EV charger usage: **(a)** full-range view and **(b)** zoomed-in view (220–240 V). Figure 5: Maximum current values in each phase during charging and non-charging periods. transformers, wires, and voltage regulators. This stress may lead to damage or reduce the lifespan of these devices. An imbalanced load distribution between different phases can cause voltage distortion, affecting power quality and the operation of connected electrical equipment.