| 摘要 |
PURPOSE:To know the amount of discharged charge by a method wherein a change in a magnetic field caused by a minute current pulse generated in a lead wire by a discharge of an electric apparatus is detected as magnetic acoustic emission (AE) by an AE sensor and the discharge is detected therefrom. CONSTITUTION:A cable 4 of a motor 3 to be tested is passed through a magnetic body 2 for magnetic field detection to which an AE sensor 1 is fitted fast. When a power source is connected to the cable 4 in this state, a power is supplied to the motor 3, the motor is rotated, and when insulation is deteriorated, a partial discharge occurs in the motor 3. At this time, only a change caused by a magnetic field generated from a current pulse generated by the partial discharge is detected in the magnetic body 2 for magnetic field detection, magnetic AE is generated by this change in the magnetic field and it is detected by the AE sensor 1. By measuring an output of the AE sensor 1 by an AE monitor 5, the amount of discharged charge can be known by comparison with a calibration value. |
