METHOD FOR DETECTING ELECTRONIC SYSTEM AND FRAME GROUND CONNECTION TO ELECTRIC SYSTEM

摘要

PURPOSE: A method for detecting an electronic system and a frame ground connection to an electric system is provided to improve a reliability of operation by detecting whether there is a frame ground connection of a power board and a control board. CONSTITUTION: A power board(1) converts an AC voltage into a DC voltage. The power board is independent from a main power for supplying a power and has an insulating DC-DC converter(3). A positive line and a negative line of the DC-DC converter(3) are arranged on an end part of the power board(1) as a detecting terminal(7) and a frame ground terminal(9) respectively. The detecting terminal(7) and the frame ground terminal(9) are arranged at an end part of the control board side facing the power board(1) to connect with the DC-DC converter. A photo coupler(11) is disposed between the detecting terminal and the frame ground terminal and has a photo diode that emits light when a DC flows and a diode transistor that is turned on when the photo diode emits light.