The convenient electricity we use every day is generated from hundreds of thousands of volts of ultra-high voltage at power plants, which is then converted into a low voltage that we can safely use through a complex and massive power grid.
The most important route on that journey and the core of the power grid of the Republic of Korea (the power grid where the most electrical safety managers work and the most accessible to the general public who use electricity) is believed to be the 22.9 kV distribution system.
Even at this very moment, 22.9 kV of electricity is flowing ceaselessly through factories, buildings, apartments, and schools across the country where the readers of this book work, keeping the Republic of Korea running.
Accordingly, the author wrote this book because he felt that there was a need for detailed explanatory materials, including on-site photos, for 22.9 kV distribution facilities.

This book was written to allow students majoring in electricity, who will be the main players in the future electric industry, to indirectly experience the 22.9 kV substation facility site, and to help electrical safety managers who are working for the first time after obtaining an electrical qualification increase their understanding of the major equipment that makes up the substation facility.
It was also written so that those who are currently working in electrical-related fields can use it as a study guide to obtain the Engineer (Electrical and Safety Field), the highest national technical qualification, by further improving their skills.


Even at this very moment, approximately 70,000 electrical safety managers (as of 2022) are working hard in the field to ensure the safety of facilities, and countless electrical engineers are working behind the scenes to ensure a stable supply of electricity.
However, the statistics on electric shock accidents that occur every year (electric shock accidents have a much higher fatality rate than general accidents) prove that those of us who work with electricity are always at risk of losing our lives.
That's why we must constantly strive to understand electricity better, and I believe that safety is guaranteed only when we follow safety rules to the extent that we know.
Also, as an electrician and a professional, I believe that I must manage power facilities well and strive to protect the lives and property of citizens by providing a stable supply of electricity.