| 摘要 |
<P>PROBLEM TO BE SOLVED: To detect the short circuit fault of a system exactly by eliminating the impact of a flicker load as much as possible without loading a computer heavily. <P>SOLUTION: An overcurrent relay used for fail-safe of a short circuit fault detection relay comprises a means for storing basic data including the lowest detection value of overcurrent, the number of detection times of overcurrent before poor monitoring, a setting value operating means for calculating the setting value for every number of detection times of overcurrent by using the basic data, and a means for detecting the overcurrent based on the setting value calculated by the setting value operating means, wherein the lowest detection value is obtained in the first time overcurrent detection and when the overcurrent detection exceeds a predetermined frequency under impact of a flicker load, the detection value is raised stepwise up to a preset upper limit value. <P>COPYRIGHT: (C)2009,JPO&INPIT |
