properties of the linear segment to hard characteristics, additional operating point of

the rotating speed is slightly lower than the synchronous speed. Artificial mechanical

characteristic curve of the shape of the available parameters expression profiling,

analyzes the key to catch the maximum torque, quantity of the three critical slip and

engine torque varies with the parameter change rule.

2 三相异步电动机的发动

2 of the three-phase asynchronous motor

小容量的三相异步电动机能够选用直接发动，容量较大的笼型电动机能够

选用降压发动。降压发动分为定子串接电阻或电抗降压发动、Y-D 降压发动和

自耦变压器降压发动。定子串电阻或电机降压发动时，发动电流随电压一次方

联系减小，而发动转矩随电压的平方联系减小，它适用于轻载发动。Y-D 降压

发动只适用于正常运转时为三角形联合的电动机，其发动电流和发动转矩均

降为直接发动时的 1/3，它也适用于轻载发动。自耦变压器降压发动时，发动

电流和发动转矩均降为直接发动时的 l/k2（k 为自耦变压器的变比），合适带

较大的负载发动。

Small capacity of three-phase asynchronous motor can choose direct start, capacity

can choose bigger cage motor step-down. Step-down launched into stator resistance

and reactance step-down start, Y - D step-down start and autotransformer step-down.

Step-down to launch of the stator resistance or motor, a current with a voltage to the

power connection is reduced, and a contact torque with the square of the voltage

decreases, and it is suitable for light load. Y - an D step-down applies only to the

normal operation of triangle joint motor, the start current and torque are reduced to

directly launch started a third, it is also suitable for light load. Autotransformer step-

down start, start current and torque are reduced to directly launch started l/k2 (k

variable ratio of autotransformer), appropriate with larger load.

绕线转子异步电动机可选用转子串接电阻或频敏变阻器发动，其发动转矩

大、发动电流小，适用于中、大型异步电动机的重载发动。软发动器是一种集电