| 摘要 |
PURPOSE:To diagnose securely the decline of insulation of a coil of an electric motor without measurer's sensation on the basis of the power spectral value of an oscillation frequency component which is an optional multiple of a power source frequency by flowing a test current to the electric motor and exciting electromagnetic oscillation, and detecting it from above a casing. CONSTITUTION:A single-phase commercial frequency power source with a variable voltage is used to flow a test current (about 60A maximum) to two- phase of a three-phase induction motor, and electromagnetic oscillation is excited at a coil part forcibly. It is analyzed by an oscillation sensor from above the casing. It is found by experiment that frequencies 2f0 and 4f0 which are double and four times as high as a fundamental frequency f0 exert great influence upon the diagnosis of the decline of insulation, so the diagnosis is performed by the measured value. |
