| 摘要 |
PROBLEM TO BE SOLVED: To protect a three-phase four-wire type AC power supply on a phase failure with a cost-effective structure. SOLUTION: This control unit is made up of a control circuit means 2 connected to a neutral point power source line 9n and an R-phase power source line 9r, a current detecting means 3 connected to an S-phase power source line 9s and the neutral point power source line 9n, and an exciting coil portion of a second three-phase power source opening/closing means 11 connected to the T-phase power source line 9t and the neutral point power source line 9n via the opening/closing portion of a first three-phase four-wire type AC power supply opening/closing means 10. Even if any one of the phases fails at least in a three-phase four-wire type power source line, the opening/closing portion of the second three-phase power supply opening/closing means 11 is made to perform opening operation. COPYRIGHT: (C)2007,JPO&INPIT
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