Noise terminal voltage

When using electrical and electronic equipment, harmonic noise voltage occurs at the power input terminals such as commercial outlets. Since line-conducted noise is transmitted to the power supply as noise and adversely affects other loads, it must be kept below the standard value. If you try to directly measure the line-conducted noise voltage, errors due to the impedance of the power circuit occur, making accurate measurement difficult. Therefore, to eliminate measurement errors caused by the impedance of the line-conducted noise voltage and to measure it accurately, a line impedance stabilization network (LISN) is connected between the commercial outlet and the electrical/electronic device.