| 摘要 |
PROBLEM TO BE SOLVED: To detect the existence of an open phase in a three phase power source. SOLUTION: When the switch SW of a current limiting circuit 84 is turned ON, a diode bridge DB; a smoothing capacitor Cpn; a diode bridge DB; the current limiting circuit 84; a fuse FUT; a capacitor Ctr (or Csr, Cst) of a filter F; a choke coil; a rooting to R phase are turned ON in order at a sight from an S-phase. This rooting itself exists in spite of whether an open phase exists in a T-phase, but in a normal case, a rooting (shown by a thin broken line arrow) toward the T-phase further exists in a normal case. In the case where the open phase exists in the T-phase, a voltage Vpn becomes lower in comparison with the normal case. The voltage Vpn 15 detected by a voltage detecting mechanism 100, and a difference between the normal case and the open phase in T-phase is thereby judged. |
