| 摘要 |
PURPOSE:To operate a three-phase induction motor at a high performance both when the motor has a light load and when the motor has a heavy load, by switching in a suitable manner the first windings the number of which is equal to that of pair of poles per phase provided electrically at 120 deg. intervals, and the second windings provided among the first windings. CONSTITUTION:The second windings U2, V2, W2 of a three-phase induction motor are DELTA connected, and the first windings U1, V1, W1 are connected between nodes (d), (e), (f) of the second windings and power sources R, S, T. Means K1, K2, K3 for use in connecting nodes (a), (f); (c), (e); (b), (d); respectively, are provided. These connecting means are opened when the motor has a light load, and closed when the motor has a heavy load. The windings U1, W2; W1, V2; V1, U2; are connected in parallel so that the windings as a whole are in double DELTA connection with respect to the power sources R, S, T. |
