AUTOMATIC MONITOR DEVICE FOR GROUND POTENTIAL OF METALLIC STRUCTURE IN GROUND OR THE LIKE

PURPOSE:To ensure the accurate automatic monitor for the ground potential for a long period of time, by storing the generating frequency and the time of generation of a high potential by means of a detecting box and then reading these frequency and time via a maintenance box. CONSTITUTION:The ground potential of a metallic structure in the ground, etc. is compared with the set reference voltage by a comparator 9 in a detecting box 7 to detect the high potential lower than the anti-corrosion potential. Then the frequency and time of generation of the high potential are stored in a time counter 11 that counts the clocks as well as a frequency counter 10. These stored information are read by a maintenance box 8 including a photocoupler 16, a dot printer 18, etc. As a result, no direct monitor is required for the potential with connection of an electrometer, etc. Thus the accurate ground potential can be monitored automatically for a metallic structure in the ground, etc. for a long period of time.