2024年1月12日发(作者：)

电气外文翻译--电力系统故障

Faults in the Power System

___ designs。equipment failures and interference from

external sources can still lead to faults in the electric power system。When these faults occur。the power supply from the ___ over a

wide area。If the ___ from the rest of the system。it could cause

damage to other operating equipment.

A fault occurs when two or more conductors。___ them。___ connect。This n can occur through physical metallic contact

or an arc。When a fault occurs。the voltage een the two parts is

ced to zero if the n is through metal-to-metal contact or to a very

low value if the n is through an arc。As a result。abnormally high

currents flow through the ork to the point of the fault。These

short-circuit currents are usually much greater than the ___。During the d in which the fault exists。the voltage on the system

in the near vicinity of the fault will be so low that ___。it is

essential for power system designers to anticipate points at which

faults may occur。___ during a fault。___ of the system。It is

___ on the system are opened。as such r would result in ___ the

system circuits.

It is ___ means that the system has been ___。the voltage at

the point of overload may be lower than normal。but it will not be

zero。This undervoltage n can extend beyond the point of

overload and affect the rest of the system。Although the

equipment experiencing the overload may have high ___ exceed its

thermal design limits。they are still significantly lower than those

seen in the case of a fault。As a result。service can often be

maintained。___.

Transformer failures ___ of the same winding can lead to

short circuits when ___。In some cases。major n can fail。which

can cause arcs to form een primary and secondary ___

In the case of generators。failures ___ in the same slot breaks

down。causing a short circuit in a single turn of the ___ can also

occur een one of the windings and the ___ different windings lying

in the same slot。it can cause extensive ns of the machine to short-circuit.

___ a spark gap。When the voltage exceeds a certain level。the spark gap ionizes and a current flows through the gap。which

then diverts the surge to ground。These types of arresters are

capable of handling high ___ surges and have a long service life.

Gapless (ZnO) metal oxide surge arresters。on the other hand。use a zinc oxide varistor to absorb the surge energy。When the

voltage exceeds a certain level。the varistor conducts and shunts

the surge to ground。These types of arresters have a faster

response time than active gap arresters and are better suited for low

and medium ___.

Regardless of the type of arrester used。it is important to note

that they have a limited service life and need to be ___。surge

arresters ___.

Overall。___。n operators can ensure the safe and reliable n

of their equipment.

The two main components of active gap surge arresters

(diverters) are the spark gap and the non-linear resistor。One of

the earlier designs was ___ plate gaps。which is still used in some

medium ___。___。___。particularly in EHV orks (300-750kV)。These arresters consist of spark gaps。discharge resistors。and a

grading system that monitors the n of voltage across the spark gaps.

___ materials。forming them into grains。___ een 1100 and

3500℃。The gapless ___ it increases.

To keep the stress on the system n as low as possible。a good

___.

时，必须使用能够承受系统正常相对地电压、具有抗污染能力并且能够在重复高能量放电后仍能正常运作的避雷器；

避雷器必须能够在不损坏的情况下承受由接地故障和其他系统瞬变条件引起的临时过电压，并将这些过电压释放到地线上而不会引发接地故障；

要求避雷器能够中断下列电流；

避雷器的能量吸收能力必须足够强大，即使在最严重的开关浪涌和临时过电压情况下，其温度也不会升高到热失控点；

保护等级必须尽可能地低。

新开发的ZnO避雷器具有出色的高非线性特性、能量能力和保护性能，可以满足这些条件并满足这些要求。

每年新设计的电力设备都能提高系统的可靠性，但是设备的不当使用以及外在因素的干扰可能会导致系统故障。故障时，电流和电压会变得不正常，这会影响电力的传输，如果故障设备不立即切除，会导致其他设备的损坏。

故障是由于两个或更多导体相接触造成的，接触时会有电位存在，可能是金属接触或电弧引起的。如果是前者，电压会降至零；如果是后者，电压会变得很低，大电流会流经网络到达故障处。这种短路电流会超出导线和发电机的热承受能力，导致导体烧毁或绝缘体焦化。在故障期限内，电压会变得很低，使得使用电设备无法运行。因此，系统设计者必须提前考虑可能出现故障的地方，并提供调节好的设备来切除故障设备。

过负荷和故障是两个不同的概念。过负荷是指负载超过设计值，这时电压可能会很低但不为零。过负荷的情况可能会影响系统其他部分。过负荷设备的电流会变大，但比故障时的电流小。为了避免过负荷造成的电力线发热或火灾，需要采用保险丝或断路器来保护电路。

在家庭中，过负荷的情况经常发生，例如同时插入多个电器的插头。为了避免这种情况，需要采用保险丝或断路器来保护电路。当用户增加用电器时，也需要监视配电线路以确保变压器的容量能够满足负荷增加的需求。

电力系统可能会出现各种类型的故障，由各种原因引起。在家庭中，破损的照明灯电线可能会导致故障，但是如果断路器或保险丝正常工作，电路会被自动切断。架空线路通常使用裸线架设，但是风、雪、大树、起重机、飞机和支撑物的损坏等因素可能会使导线偶然碰到一起。此外，即使在电压正常的情况下，绝缘材料的污染也可能引起电弧。

有效间隙避雷器主要由火花间隙和非线性电阻两部分组成。早期设计采用平板间隙避雷器，在一些中压供电网中仍在使用。然而，在高压电网中，特别是在超高压电网中（300~750kV），磁吹火花间隙避雷器更为普遍。该避雷器由火花间隙、放电电阻和能监测电压分布的分级系统组成。

氧化锌避雷器的材料是经过均匀混合形成晶粒，然后在温度1100~1350℃时烧结。使用氧化锌材料的无间隙避雷器的特

性是：随着电压增大其电阻值迅速减小。为了保持系统绝缘受到的应力尽可能小，一个优秀的过电压保护系统或避雷器应满足以下要求：

1.在其运行寿命中，即使在污染的情况下或电网可能出现的大能量重复放电后，它必须能承受系统的正常的相对地电压；

2.它必须能承受由姐弟故障和其他系统过渡状态造成的短时过电压而不被破坏，并且这些过电压对大地放电不会导致接地故障；

3.能够断开续流电流；

4.它的能量吸收能力必须满足这种情况，即在最严重的操作过电压和短时过电压下，其部件的温度也不能升高到散热允许的设定值；

5.它必须维持尽可能低的保护水平。