| 摘要 |
PROBLEM TO BE SOLVED: To provide an inverter which contains an interconnected system protecting function and can detect service interruption of AC power system, under various installation conditions. SOLUTION: The phase of an output current of an inverter main circuit 11 changes in each of the predetermined phases. When service interruption of a commercial AC power source is generated in the case of power supply to a load 14, the voltage frequency of the load 14 sequentially changes in accordance with the operation for power factor improvement by the inverter main circuit 11, during each phase period. When the change rate of voltage frequency of the load 14 exceeds a predetermined threshold, a detection part 16 of phase and frequency change rate tells the fact to a system voltage abnormality detection part 18, and the frequency change rate about each phase is stored in a substorage device 17. On the basis of information or the like from the detection part 16, the system voltage abnormality detection part 18 judges the service interruption of the commercial AC power source, and stops the inverter main circuit 11. |
