| 摘要 |
PURPOSE:To make it possible to detect a fault of a DC power source beforehand by detecting finely a change in an output voltage and by generating an alarm signal in a premonitory stage of abnormality. CONSTITUTION:An alarm signal A is not outputted when a DC power source 1 is normal. When an output voltage V0 turns unstable as a premonitory symptom of a fault, a ripple component contained in the output voltage V0 increases and therefore an waveform amplitude of an alternating-current signal F becomes large. When a rectification signal G exceeds a reference voltage VRE, a comparator 3A outputs a comparison signal CA and thereby an alarm generating circuit 4 is driven to output the alarm signal A. By making the alarm signal A be generated at a time point when the ripple component of the output voltage V0 exceeds an allowable limit value, in this way, an alarm device can be driven without fail in a precursor stage of complete abnormality of the DC power source 1, and thereby a monitoring device can be minimized. |
