| 摘要 |
PURPOSE:To make it possible to inspect easily and surely the state of internal defect for a single unit of squirrel cage rotor in a non-destructive inspection method for internal defect of squirrel cage conductor. CONSTITUTION:A squirrel cage rotor 1 comprises a stator core 2 equipped with a squirrel cage conductor 3 made of a slot bar 6 and end rings 7; and 3 ducts 5 for cooling are extended in radial direction at the intermediate portion of the rotor core 2. A constant DC current is applied between both the end rings 7, 7 from a DC power supply 8, and voltage between two points of the slot bar 6 is measured with a voltmeter 9, and the electric resistance of each slot bar 6 is measured. If an internal defect occurs, then the electric resistance of this portion increases, so that the integrity of the squirrel cage conductors can be evaluated based on electric resistance value measured. |
