METHOD OF INSPECTING SQUIRRELLCAGE ROTOR

摘要

PURPOSE:To surely detect the defective part of a rotor bar without destroying a rotor, by placing an annular core around the rotor, energizing a coil around the core, detecting the rise in the temperature of the rotor due to an induced current by a thermometer and comparing the detected temperature rise with a prescribed value. CONSTITUTION:A squirrel-cage rotor 1 die-cast with aluminium is supported by bearings 6. Annular cores 7 for inspection are placed at the ends of the core of the rotor 1. A polyphase AC power source 9 is connected to a winding 8 to excite the core 7. A current is induced in the conductor 11 of the rotor by the magnetic flux of the core 7. If the conductor 11 has a defective part such as bar cut-off, the resistance of the conductor is high and the temperature of the core near the conductor 11 is higher than that of a non-defective conductor. The temperature of the core is measured by a thermometer 10 provided near the surface of the rotor 1 while the rotor is rotated by every slot pitch by a rotary driver 12. The conductor 11 is insepected on defects along the total circumference of the rotor 1.