초록
The latest equipment automatic Intelligence of digital base done large size equipment appear in succession. That run by voltage electric current(mA, mV, ${\mu}A,\;{\mu}V$) that outline is microscopic of action of accuracy large size equipment of this digital base is bulk. Have received influence that is great in river electric field by installment that use computer. Most of domestic working voltage from service entrance extra-high voltage and working voltage of commercial frequency 60Hz working voltage 220V that use our country outside 1 country in interior of 22.900V for semiconductor use computer use digital installment of appliance as well as various smalls of digital base, middle, large size that safety is these fine voltage electric current that is not enough direct admonition hundred vast damage give can. Also, already act in surge circle and impulse transient phenomena such as several thousands, myriads, strong bit error more than billions time to digital fine electronic circuit by mistake use of using electric facility system of system electric power.