| 摘要 |
PROBLEM TO BE SOLVED: To obtain an electromagnetic operation switching device capable of batch operating of AC three-phase easily and inexpensively. SOLUTION: An electrode switching time measurement device 50 inputs the current flowing in an electrode closing coil 13 of each phase from electrode closing current measuring units 43u-43w, and calculates the electrode closing forecast time of each phase by the current waveform input by its electrode switching time forecast means 64. An electrode closing timing adjusting circuit 53 compares the electrode closing forecast time of each phase by its electrode closing forecast time comparison means 66 and its electrode closing timing control means 67 outputs a switch-on signal to electrode closing command switches 33u-33w of each phase in the order from the phase with the longest electrode closing forecast time and, thereby three-phase batch operation is achieved. COPYRIGHT: (C)2008,JPO&INPIT
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