求电专业英语翻译￥￥A three-phase electric circuit is energized by three alternating emfs of the same frequency and differing in time phase by 120 electrical degrees. Three such sine-wave emfs are shown in Fig. 1-1B-1. These emfs are genera

求电专业英语翻译￥￥A three-phase electric circuit is energized by three alternating emfs of the same frequency and differing in time phase by 120 electrical degrees. Three such sine-wave emfs are shown in Fig. 1-1B-1. These emfs are genera
求电专业英语翻译￥￥
A three-phase electric circuit is energized by three alternating emfs of the same frequency and differing in time phase by 120 electrical degrees. Three such sine-wave emfs are shown in Fig. 1-1B-1. These emfs are generated in three sets of coils are mounted 120 electrical degrees apart on the generator armature. The coil ends may all be brought out of the generator to form three separate single-phase circuits. However, The coils are ordinarily interconnected either internally or externally to form a three wire or four-wire three-phase system.
Active electrical elements occur in two basic forms: Voltage sources and current sources. In their ideal form, voltage sources generate a constant voltage independent of the current drawn form the source. The aforementioned battery and generator are regarded as voltage sources since their voltage is essentially constant with load, On the other hand, current sources produce a current whose magnitude is independent of the load connected to the source. Although current sources are not as familiar in practice, the concept does find wide use in representing an amplifying device, such as the transistor, by means of an equivalent electrical circuit. Symbolic representations of voltage and current sources are shown in Fig. 1-1A-2.

求电专业英语翻译￥￥A three-phase electric circuit is energized by three alternating emfs of the same frequency and differing in time phase by 120 electrical degrees. Three such sine-wave emfs are shown in Fig. 1-1B-1. These emfs are genera
三相电源电路由3个相同频率,时间差为120度电角度的电动势驱动.这种电动势的三个正弦波样式如图1-1B-1所示.这些电动势由发电机电枢上安装的分隔120度电角度的三组线圈产生.线圈的末端均可以从发电机内单独引出以形成三个分离的单相电路.通常线圈在内部或外部进行互连以形成三相三线或三线四线系统.
主动（有源）式的电气元件通常以两种基本形式出现：电压源或电流源.理想情况下,无论从电压源吸取多大的电流,其输出电源均保持恒定.上面所讲的电池及发电机即可视为电压源,因为它们的输出电压随负载变化基本上是恒定的,从另一方面讲,电流源产生的电流大小与接在其上的负载大小没有关联.尽管在实际中电流源并不为人所熟知,这种概念在表征放大装置时却有很广泛的应用,例如晶体管,通过等效电路,电压源及电流源的图形化符号如图1-1A-2所示.