Electricity, which is essential for EMUs to run, is sent from a substation to the contact wire stretched over the tracks (feeding). EMU pantographs contact the contact wire, which draws electricity into the railcar (current collection), and this electricity is then consumed by the motors and various other railcar equipment. After completing its role, the electricity returns to the substation through rails and feeder lines (current return). There are two types of electrical power, DC and AC, each with its advantages and disadvantages. The challenge for AC feeders is to reduce inductive communication interference; however, the original system had sections in the contact wire, which made it difficult to control train noise. New feeding systems that have solved this problem will be presented, compared with the old system. The most critical issue for the current collection is to minimize contact loss, which occurs when the pantograph detaches from the contact wire. The causes and effects of large and small contact loss are introduced. Additionally, the mechanism of the catenary system and pantographs is introduced to minimize contact loss, noise, and maintenance.