| 摘要 |
PURPOSE:To enable to perform a simple and reliable judgement of the quality of a slot insulation, by a method wherein an excitation is conducted so that a vector sum of a magnetic flux of a plurality of magnetic paths formed in a manner to bring probe magnetic cores, provided with exciting coils, into contact with a cage rotor surface attains a 0 valve. CONSTITUTION:A probe magnetic cores 3 and 4 are brought into contact with a surface of a cage rotor having a rotorcore 1 and rotor bars 2 to form two magnetic paths togetherwith the rotor core 1. Exciting coils 5 and 6, connected to an AC power source 9, and secondary coils 7 and 8 coupled to a voltmeter 10 are then wound around probe magnetic cores 3 and 4. The exciting coils 5 and 6 are excited in a reverse direction to each other, or so that a vector sum of magnetic fluxes interlocking the rotor bars 2 attains a 0. In which case, if a slot insulation of a cage rotor is poor, a loss, being inversely proportional to a contact resistance R between the core 1 and the bars 2 is produced, and this permits the discrimination of the quality thereof from the indication of the voltmeter 10. |
