| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To surely and easily detect a mold crack having been generated in a solid insulated switch itself or its connecting conductor without providing the switch with a special sensor. <P>SOLUTION: A detector 4 detects a high-frequency oscillating current by LC resonance flowing to the grounding line of the solid insulated switch 3 by the generation of a mold crack or the occurrence of an external grounding accident, and extracts only the high-frequency oscillating current having a frequency band peculiar to the mold crack contained in this detected current by means of a band pass filter, and when the amplitude level of the high frequency oscillating current is at or over a certain value and exists the certain number of times or over within a certain time, the generation of the mold crack is determined. <P>COPYRIGHT: (C)2005,JPO&NCIPI</p> |
