Question

求高手翻译一段电气工程及自动化专业的专业英语，不用词霸的，急

I. INTRODUCTION

Electric power systems are exposed to overvoltages of
different origin which might endanger the equipment such as transformers,
instrument transformers or circuit breakers, only to name a few. Fig. 1
summarises the different kinds of overvoltages as a function of their duration
in comparison to the highest voltage for equipment. Lightning strokes into the
electric power system or its vicinity lead to lightning overvoltages in the
range of microseconds, switching action within the system cause switching
overvoltages in the range of milliseconds and certain operating conditions due
to load flow control cause temporary overvoltages which can last for several
seconds.

As can be seen from Figure 1, the equipment is designed to
withstand the highest voltage for equipment as well as temporary overvoltages.
However, the insulation of the equipment is not capable of withstanding
lightning and switching overvoltages. Without countermeasures, occurrences of
these overvoltages in the system can lead to breakdown of the equipment
insulation and its failure.

In order to protect electric power system equipment from
lightning and switching overvoltages, surge arresters are used within the
system as a tool for insulation co-ordination. The purpose of using a surge
arrester is to always limit the voltage across the terminals of the equipment
to be protected below its insulation withstand voltage.

This is achieved by connecting elements with an extremely
non linear voltage current characteristic (varistor) in parallel to the
terminals of the equipment. So called metal oxide (MO) surge arresters
containing ceramic MO elements mainly made from zinc oxide (ZnO) and bismuth
oxide are used nowadays [1]. Due to the high non linearity of the material
there is no need for series spark gaps any more as they were used in silicon
carbide (SiC) surge arresters.

Per
the NEC 2005, a surge arrester is defined as: “A protective device for
limiting surge voltages by discharging or bypassing surge current, and it also
prevents the flow of follow current while remaining capable of repeating these
functions”.

In figure 2, an Example is shown of a typical MO arrester
connected between phase and ground in a solidly earthed neutral 420-KV system.
On the Ordinate the voltage peak value is depicted linearly, while on the
abscissa current peak value are given in a logarithmic scale. In the depiction,
the characteristics extends over a current in the range of 50µA to 50kA, that
is, over nine decades of magnitude.

The power-frequency voltage, while continuously applied to
the arrester, is the highest phase-to-earth voltage of the system. In this case
peak value is:-

Vm=√2
. Vs/√3= √2. 420kV/√3= 343kV

Answer 1

一，引言电力系统暴露于不同的起源可能危及设备，如变压器，仪表互感器或断路器的过电压，只是仅举几例。图。1 总结了不同种的过电压，它们的持续时间的函数的比较设备最高电压。到电力系统或其附近的雷击导致在微秒范围内的雷电过电压，开关动作系统内的开关过电压的毫秒的范围和一定的操作条件下，由于负载流量控制造成的暂时过电压可以持续数的原因秒，从图1中可以看出，该设备被设计承受的最高电压的设备，以及暂时过电压，但是，不能够承受雷击和开关过电压的设备的绝缘。如果没有对策，这些系统中的过电压的出现可以导致故障的设备绝缘，它的失败。为了保护设备免受雷电和开关过电压的电力系统，避雷器在系统中使用的工具，绝缘合作协调。的目的，使用了电涌避雷器是始终限制在低于其绝缘耐压要保护的设备的端子间的电压，这是通过连接元件与一个极其非线性电压电流特性（压敏电阻）并联到端子的设备。时下使用所谓的金属氧化物（MO）的避雷器，包含主要由氧化锌（ZnO）和铋的氧化物的陶瓷MO元件[1]。由于高非线性的材料也没有必要每对NEC 2005，避雷器被定义为：“甲保护装置限制为系列火花隙任何更多的，它们被用来在硅碳化物（SiC）的避雷器。浪涌电压的放电或浪涌电流旁通，并且它也可以防止后续电流，同时剩余能够重复这些函数“ 的流，在图2中，一个实施例示出一个典型的MO避雷器相和接地之间连接在直接接地的中性420千伏系统，在纵坐标的电压峰值直线描绘，而给出在对数刻度上的横轴电流峰值。在描绘的特性延伸超过在50μA的范围内的电流为50KA，即，超过9十年的级的功率的高频电压，同时连续地施加到避雷器，是最高的相-地电压系统。在这种情况下峰值为： - 以Vm =√2 。与/√3 =√2。420kV /√3 = 343kV

Answer 2

出钱，我给你翻译。