| 摘要 |
PURPOSE: A ground wire robbery preventing apparatus is provided to deal with robbery and safety accidents by accurately and rapidly grasping whether a ground wire is cut or is disconnected or not. CONSTITUTION: A ground wire robbery preventing apparatus(300) comprises disconnection detecting units(310,320), an OR calculation circuit(350), a signal amplifier(360), and a driving unit(370). The disconnection detecting units are electrically connected to a ground wire of a ground rod and detect the disconnection of the ground wire. The disconnection detecting units output an ON-detection signal during a predetermined time when the ground wire is disconnected. The OR calculation circuit performs a logical summation function according to an output signal detected in the disconnection detecting units and outputs a calculated signal. The signal amplifier amplifies the calculated signal outputted from the OR calculation circuit and outputs it. The driving unit level-shifts an output signal outputted from the signal amplifier and supplies a driving current in a speaker connected to outside.
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