Transformers 变压器
The purpose of the transformer is to isolate the different parts of the electric power distribution system into several partitions, normally in order to obtain different voltage levels and sometimes also for phase shift. Phase shifting transformers can be used to feed frequency converters, e.g. for variable speed propulsion drives, in order to reduce the injection of distorted currents into the electric power network by canceling the most dominant harmonic currents. This reduces the voltage distortion for generators and other consumers. The transformers also have a damping effect of high frequency conductor emitted noise, especially if the transformer is equipped with a grounded copper shield between primary and secondary windings.
译文：变压器的目的是将配电系统的不同部分隔离成几个分区，通常是为了获得不同的电压电平，有时也是为了相移。移相变压器可用于馈送变频器，例如用于变速推进驱动，以便通过消除最主要的谐波电流来减少畸变电流注入电力网络。这减少了发电机和其他用电设备的电压失真。变压器还具有高频导体发射噪声的阻尼效果，特别是如果变压器在初级绕组和次级绕组之间配备了接地铜屏蔽。
There are numerous different transformer designs in use, and the most common types are; air insulated dry type, resin insulated (cast or wound), or oil/fluid insulated. Regulations, ambient conditions, and user’s, yard’s, or supplier’s preferences govern the selection of type, material, and design of the transformer.
译文：在使用中有许多不同类型的变压器，最常见的类型是：；空气绝缘干式、树脂绝缘（铸造或缠绕）或油/流体绝缘。法规、环境条件以及用户、工厂或供应商的偏好决定了变压器的类型、材料和设计的选择。
Physically, the transformer is normally built as three-phase units, with three-phase primary coils and three-phase secondary coils around a common magnetic core. The magnetic iron core constitutes a closed path for magnetic flux, normally with three vertical legs and two horizontal yokes; one in bottom and one at top. The inner winding constitutes the low voltage or secondary windings, and the outer is the primary or high voltage winding. The ratio of primary to secondary windings gives the transformation ratio. The coils may be connected as a Y-connection or △-connection (also called D-connection). The connection may be different on primary and secondary sides, and in such transformers, not only the voltage amplitude will be converted, but there will also be introduced a phase shift between the primary and secondary voltages. The phase shift can also be adjusted by use of Z-connected windings, normally in the primary, where the phase shift angle can be accurately determined by the ratio of turns in the segments of the Z-windings. Three or four winding transformers with multiple secondary windings are also in use, e.g. for multi-pulse drive applications.
译文：从物理上讲，变压器通常作为三相单元构建，三相初级线圈和三相次级线圈围绕一个公共磁芯。磁性铁芯构成磁通量的闭合路径，通常具有三个垂直腿和两个水平轭；一个在底部，一个在顶部。内部绕组构成低压或次级绕组，外部绕组构成初级或高压绕组。初级绕组与次级绕组的比率给出了变比。线圈可连接为Y形连接或△-连接（也称为D连接）。一次侧和二次侧的连接可能不同，在这种变压器中，不仅电压幅值将被转换，而且在一次电压和二次电压之间还会引入相移。相移也可以通过使用Z连接绕组进行调整，通常在初级绕组中，相移角可以通过Z绕组分段中的匝数比精确确定。具有多个次级绕组的三或四绕组变压器也在使用中，例如用于多脉冲驱动应用。
A transformer with △-connected primary and Y-connected secondary is called a Dy type transformer. The first and capital letter describes the primary winding, and the second and small letter describes the secondary winding. The letter n is used to describe if the common point in a Y-connection is grounded, e.g. Dyn or Ynyn.
译文：变压器△-连接的初级和Y连接的次级称为Dy型变压器。第一个大写字母表示初级绕组，第二个小写字母表示次级绕组。字母n用于描述Y连接中的公共点是否接地，例如Dyn或Ynyn。
Transformers may be designed according to IEC standards. For converter transformers, it is essential that the design accounts for the additional thermal losses due to the high content of harmonic currents. IEC also gives design rules and guidelines for such applications.
译文：变压器可根据IEC标准设计。对于换流变压器，设计中必须考虑到由于谐波电流含量高而产生的额外热损耗。IEC还为此类应用提供了设计规则和指南。
New Words and Expressions
partition [pɑːˈti∫ən] n. 分割；分开；被分开；区分，划分，配分
harmonic[hɑːˈmɔnik] n. 谐波；谐音
damping[ˈdæmpiŋ] n. 阻尼，减幅，衰减
insulate[ˈinsjuleit] vt. 使绝缘；使绝热
ambient [ˈæmbiənt] adj. 包围着的，周围的
magnetic [mægˈnetik] adj. 磁（性）的；（可）磁化的
flux [flʌks] n. 流量，通量，电通量，磁通量
horizontal [ˌhɔriˈzɔntl] adj. 地平的，地平线的
yoke [ jəuk] n. 轭状物
thermal [ˈ θəːməl] adj. 热的，热量的，温热的；由热造成的
Notes
（1）“…not only the voltage amplitude will be converted, but there will…”
not only... but... 不但……而且…… 这里but后省略了also，“not only …but also…”是并列连词，通常连接两个等同的成分。它所连接的两个等同成分强调后者。
例如：
1）Furthermore, education is not only just about knowledge but also about values.
此外，教育并不只求知识的传授，也重视价值观的培养。
2）We will protect not only individual rights, but also must shoulder collective responsibilities.
我们保障个人权利，但也应该承担集体责任。
（2）“… for the additional thermal losses due to the high content of harmonic currents.”
due to 由于, 应归于
例如：
1）Inability to stand due to muscular incoordination.
由于肌肉不协调而不能站立。
2）His illness was due to overwork.
他的病起因于过度劳累。
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