| 摘要 |
PURPOSE:To change over the Y-DELTA starting of an induction motor at an ideal point by a method wherein the currents of an end ring of a cage type rotor are detected through a noncontact type magnetic current converter. CONSTITUTION:Secondary currents corresponding to the number of revolution by the rotation of a motor flow through an end ring 1 of a cage type rotor, and magnetic flux 5 is generated. The magnetic flux 5 is detected by means of a magnetic current converter 6 installed around the end ring 1, extracted as the change of voltage, and utilized as the change-over signals of a Y-DELTA change-over means for starting. Thus, if the most ideal number of revolution for change-over is previously set from the relationship of torque in case of Y and torque in case of DELTA, starting can be changed over to DELTA from Y when the rotation reaches the number of revolution, and starting can excellently be changed over even when voltage and load change. |
