| 摘要 |
PROBLEM TO BE SOLVED: To make it possible to measure the current of a three-phase main circuit and detect the phase failure of the circuit using two units of current transformers, and to improve the structure of the current transformers in such a way that power supply can be stabilized by suppressing the input fluctuation width of an operation power supply that is fed from the current transformers to a processing circuit. SOLUTION: In a current detecting device for a three-phase main circuit that is made up of current transformers 5 inserted in the main circuit 3 that feeds electric power from a three-phase power supply 1 to a load 2 and a processing circuit 6 that uses the secondary outputs of the current transformers as operation power sources, and that detects the current and operation state (the phase failure) of the main circuit by inputting the output signals of the current transformers into the processing circuit, the current transformers of a primary penetration type are used and one current transformer CT1 is inserted over the R- and S-phases of the main circuit 3, and the other one CT2 over its S- and T-phases. Based on the output signals obtained by the two units of the current transformers, the current value of each phase of the main circuit is measured and the phase failures is detected by the processing circuit 6 discriminating two conduction states between a one-phase failure and a two-phase failure. COPYRIGHT: (C)2005,JPO&NCIPI
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