| 摘要 |
<p>PURPOSE:To detect the extent of the loosening of a stator coil precisely even if a primary current contains many opposite-phase current components due to the unbalance of a primary voltage by providing an opposite-phase current value difference calculating means which calculates the amplitude of the mutual difference between the opposite-phase current values. CONSTITUTION:Primary currents of phases U and W among primary currents of phases U, V, and W of a three-phase induction motor 1 are detected by current transformers 12 and 13 and A/D-converted by A/D converters 14 and 15, their waveform data are stored in memories 16 and 17, and the stored data are processed by a CPU 18. Namely, the CPU 18 connects a rated load and no load (or light load) as the load 21 of the motor 11 and carries out waveform data collection processing, Fourier analytic processing, opposite-phase current value calculation processing, etc., to find the opposite-phase current value. Then, the amplitude of the difference between the opposite-phase currents in both primary currents and displays the amplitude on a display device 19 as the standard for the loosening of the stator coil.</p> |
