Abstract: An apparatus for estimating the lifetime of a surge protective device (SPD) using the discharge characteristics of a metal oxide varistor (MOV) includes an MOV having an input terminal and an output terminal; an impulse voltage application unit applying an impulse voltage for MOV test to the input terminal of the MOV; a discharge current measurement unit; a first switching unit connecting a power line to the input terminal of the MOV; a second switching unit connecting a ground line to the output terminal of the MOV in the normal mode and selectively connecting the discharge current measurement unit in the MOV test mode; an MOV test management unit providing information; a discharge current check unit generating an MOV abnormal signal; and an MOV state display unit displaying an MOV abnormal signal.

Abstract: A ground electrode (100) positioned in the earth and a monitoring device (200) configured to measure a current and resistance of a ground line, where the monitoring device (200) includes a ground current sensing unit (210) configured to measure the current of the ground line, a resistance sensing unit (220) configured to measure ground resistance of the earth and an earth resistance rate, a voltage sensing unit (230) configured to check a voltage value of commercial power, a temperature and humidity sensing unit (240) configured to check a surrounding temperature and humidity of the monitoring device (200), and a monitoring unit (250) configured to confirm whether the ground current, ground resistance and earth resistance measured are abnormal values by compared with reference values classified based on the temperature and humidity measured.

Abstract: An apparatus for checking damage to a surge protector and automatically changing a surge protector includes a casing, a current inflow unit supplied with an external current, a current discharge unit configured to supply an inflow current to an external electronic device, surge protectors placed between the current inflow unit and the current discharge unit in parallel, selectively connected to the current inflow unit, and supplied with an electric current, a relay placed between the current inflow unit and the surge protectors and configured to selectively connect the surge protectors to the current inflow unit, and a surge protector damage check unit configured to check whether a surge protector connected to the current inflow unit has been damaged by applying a voltage between the current inflow unit and the current discharge unit.