抄録
It is well known that the voltage drop due to the inrush current at energizing transformer, may at times, interrupt electrical equipment. Generally, the voltage drop is calculated by using the sophisticated tool such as EMTP, so the transformer saturation phenomenon has been properly represented. However, it is not practical for distribution system engineers to calculate the voltage drop with transformer inrush by using EMTP, because there are a lot of network access requests needing such calculations with many kinds of transformers. Therefore, in this paper, a simplified and easy-to-use calculation tool for voltage drop caused by transformer inrush in distribution system is developed. In order to grasp the voltage drop by inrush current during the planning stage, it is formulated by considering the transformer saturation/unsaturation periods in each winding type, the developed tool is based on the versatile spreadsheet software such as Microsoft Excel®. It can be used with accuracy almost similar to the EMTP.
