Development of polymeric surge ZnO arresters for 500-kV compact transmission line

The 500-kV polymeric ZnO surge arresters for compact transmission line against lightning overvoltage were developed and have been put into operation, which consists of arrester unit and series gap. The design of the arrester unit, including structure design, selection of ZnO varistor, parameter determination, polymeric housing design, and mechanical structure design was discussed. The design of the series gap and the determination of the series gap length were presented. The calculated results state the line surge arrester can highly improve the lightning withstand level of the compact transmission line, and the line surge arrester can withstand the effects of lightning.     

Effect of overhead ground wires on reduction of failure rates of surge arresters on power distribution lines

Surge arresters are sometimes damaged by lightning strokes with high energy, in spite of installation of conventional protection methods. In order to reduce the number of failures of surge arresters, we should consider another protection method, such as an increase in the withstand capability of surge arresters and installation of additional overhead ground wires. However, quantitative comparison of these methods for preventing damage to surge arresters against lightning strokes with high energy has never been performed. This paper describes the effects of additional overhead ground wires for preventing damage to surge arresters. The main results are: (1) The failure rate of surge arresters on a distribution line with two overhead ground wires is about one third of that with an overhead ground wire. (2) Installation of a second overhead ground wire six to eight spans from the end of a line reduces the failure rate of a surge arrester at the end as effectively as increasing the withstand capability by a factor of two. © 1998 Scripta Technica. Electr Eng Jpn, 122(2): 12–20, 1998     

Analytical Method for Coordination of Surge Arresters with Current-Limiting Fuses

Many industrial power systems have lightning exposure, requiring surge (lightning) arresters; dry-type transformers, requiring low protective levels; and high available fault currents, making the use of current-limiting fuses desirable. On occasion, current-limiting fuse arc voltages have resulted in destruction of low characteristic arresters. A traditional guideline has been to select arrester types and ratings that will not spark over on current limiting fuse maximum arc voltage?an approach that may not be entirely viable for industrial systems. A step-by-step analytical approach to the selection of surge arresters for use with current-limiting fuses is presented. The method presumes arrester sparkover and is based on determination of system energy, fuse arc voltage and arrester back voltage characteristics, and arrester energy capability.     

Impact of surge arrester number and placement on reliability and lightning overvoltage level in high voltage substations

Surge arresters are the most critical equipment for protecting high voltage substations. They play an important role in substations for limiting switching and lightning surges and diverting these surges to ground. On the other hand, surge arrester number and placement for high voltage substations can be determined based on some evaluations in the designing process of substations. Surge arresters can be placed on the both ends of substations, transformers, circuit breakers, reactors, capacitors and also high long bus-bars and etc. Therefore, failure of arresters during overvoltage can put substations in risk condition. Moreover, surge arresters may be inclined to be short circuit during normal operation condition due to ageing process and/or improper quality. This paper attempts to assess reliability of three common substation configurations namely: (1) one breaker and a half; (2) double-bus double-breaker; and (3) ring bus-bar in different placement of surge arresters. At first, maximum voltages on equipment are calculated in different lightning stroke locations through simulation in EMTP-RV. Studies without surge arrester and the presence of surge arrester in different locations are analyzed and compared. Then surge arrester’s placement impacts on the substations reliability indices are calculated in normal operating condition and overvoltage condition by minimal cut set method and simulation results. Analytical studies reveal that surge arrester can increase substations reliability. But for low annual number of lightning stroke, substation reliability may decrease. Also increasing surge arrester number more than substation need reduces reliability.     

输电线路避雷器断串分析与防范

目前采用的线路型避雷器多为绝缘子间隙避雷器。运行单位在安装线路避雷器时主要考虑的是避雷器的电气性能,很少对避雷器的安装形式和运行状态下的受力情况进行分析,以至运行中出现掉串现象。例举了一起线路型避雷器断串缺陷,通过计算分析得出断串的原因,并提出了避雷器安装的防范措施。     

具有绝缘子性能避雷器的结构设计与试验分析

高压输电线路通常采用线路避雷器并联绝缘子的方式作为其防雷措施,从而保证绝缘子在雷电时免受过电压闪络损伤,而此方式却造成线路和铁塔的负荷增大,线路设施复杂化。针对上述问题设计了一种具有绝缘子性能的避雷器,结合绝缘子和避雷器的试验标准以及设备的结构特点进行了试验研究和测试,并给出明确的试验项目和测试结果。     

A Procedure for Estimating the Lifetime of Gapless Metal Oxide Surge Arresters for AC Application

The development of the gapless metal oxide (ZnO) surge arrester has presented the arrester engineer with new materials and an opportunity for new designs. This situation arises because the gapless surge arrester is electrically active throughout its lifetime whereas its predecessor, the silicon carbide arrester, was electrically passive being electrically isolated with gap structures. The prime consideration is one of reliably estimating the lifetime of a gapless ZnO surge arrester under continuous ac stress while maintaining the capability not only to limit surge voltages but also to absorb energy inputs resulting from lightning or switching surges and temporary overvoltages. In this paper we establish a procedure for reliably estimating the lifetime of gapless metal oxide surge arresters for ac application by incorporating the device characteristics into design requirements. This method is illustrated for metal oxide surge arrester elements that exhibit a predictable linear resistive current versus time1/2 behavior as a function of applied voltage and temperature.     

陕西地区配电线路新型防雷装置研究与应用

针对陕西地区配电线路避雷器防雷效果不理想这一现状,提出一种多腔室雷击闪络限制器。该装置防雷性能优异,采用吹弧原理,熄弧能力强。经过试验,确定其串联级数为26级,电极直径8 mm,电极间隙1 mm,主间隙距离取45 mm时能可靠动作。工频湿耐受电压、50%雷电冲击动作电压、雷电冲击伏秒特性以及工频续流遮断能力均满足标准要求。装置在陕西地区典型线路上运行良好,防雷效果优异。     

复合外套避雷器在昌房500kV紧凑型线路的防雷效果分析

５００ ｋＶ昌房紧凑型线路采用线路避雷器后,能较大地提高线路的耐雷水平。紧凑型线路避雷器本体的荷电率取０．９,完全能承受雷击杆塔时的放电电流和放电能量。     

Minimum Distance of Lightning Protection Between Insulator String and Line Surge Arrester in Parallel

The line surge arrester can effectively improve the lightning protection performances of transmission lines by eliminating the insulator flashover. If the line arrester is very close to the insulator string in parallel, the lightning discharging would take place in the gap between the upper discharging ring of the line arrester and the bottom grading ring of the insulator string, there is no discharging in the series gap of the line arrester. Sometimes, the insulator string would have a flashover, the line surge arrester cannot provide protection for the insulator string. This so-called “transverse discharge” phenomenon is caused by the proximity effect of the discharging ring of the line arrester. This phenomenon is explained in this paper, and the transverse discharge phenomenon is simulated in high voltage laboratory. The demanded minimum distances between the 110-kV and 220-kV line arrester and insulator string protected are proposed from experimental results.      

Investigation of effect of transmission line arresters verified by lightning surges at substations

In recent years, transmission line arresters have been installed to protect overhead power transmission lines from backflashovers caused by lightning. In addition, it has been expected that substation lightning surges incoming via transmission lines can be suppressed by them. However, the suppression effect by those with series gaps has not been investigated sufficiently. The author has measured lightning surges at two 77‐kV substations from 1990 to 1993. As the transmission line arresters have been mounted on the towers since 1992, the lightning surges due to the sparkover of the series gap of the transmission line arresters can be observed at the substations. In this paper, the lightning surge waveforms due to such sparkover have been analyzed in detail. Next, an accurate EMTP simulation method considering the induced lightning surge voltages has been proposed. Finally, their suppression effect has been investigated by simulation corresponding to each mounting method. © 1999 Scripta Technica, Electr Eng Jpn, 126(4): 30–39, 1999     

Rocket-triggered lightning experiments on zinc oxide arresters and their applications to power transmission lines

In measurements of rocket-triggered lightning current and voltage performed between 1986 and 1995 on the mountain top of Okushishiku in the Kanazawa area, the authors succeeded in artificially inducing winter lightning to arresters. Using the data obtained from those measurements, we analyzed the energy absorption characteristics of surge arresters, such as are installed on every transmission line tower for three phrases, by EMTP. The energy withstand capability of an individual arrester was verified to be approximately the same as the expected value. The analysis results for the energy share of each arrester connected in parallel showed that the usual light duty arresters installed on every tower have the possibility to be able to absorb extreme winter lightning energy even if the lightning hits the power line directly. © 1998 Scripta Technica. Electr Eng Jpn, 122(4): 25–33, 1998     

Lightning overvoltage protection of AC railroad vehicles bypolymeric arresters

In order to improve the operational reliability of AC railroad vehicles, ZnO surge arresters are used to protect them against overvoltages. The most serious threat to arresters installed on the roof of an AC railroad vehicle is the lightning overvoltage. When lightning strikes the mast or conductors, the distribution system can be treated as a system of multiple conductors including feeders, messenger wires, contact wires, protective wires and two tracks. The lightning impulse discharge current through the arrester and the absorbed impulse discharging energy by arrester in the actual field operation and the protective effect of arrester were analyzed by EMTP and discussed when lightning strikes the mast or distribution lines. When the arrester Is installed on the roof of a railroad vehicle, the potential difference on the primary side of high voltage transformer inside the vehicle is suppressed below 150 kV under very serious condition     

500 kV线路避雷器保护失效分析及改进措施研究

线路避雷器是防止输电线路雷击跳闸的有效手段,随着高电压等级线路避雷器的使用,出现了因安装方式导致的线路避雷器保护失效问题。针对某500 kV输电线路发生的线路避雷器在大幅值雷电流反击下对绝缘子串保护失效的问题,采用电磁暂态分析软件ATP-EMTP建立了仿真分析模型,分别对雷电流绕击和反击情况下绝缘子串和线路避雷器两端承受的电压进行了量化,得出了导致反击情况下线路避雷器保护失效的原因;提出了对现有500 kV线路避雷器安装方式的改进方案,并对改进方案下反击雷电流导致的绝缘子串和线路避雷器两端电压波形进行了比较,验证了改进措施的有效性。所研究成果对于500 kV及以上电压等级线路避雷器的使用具有重要参考价值。     

Development of a detection device for deteriorated ZnO surge arresters at AC traction substations

This paper presents a novel detection device for deteriorated zinc‐oxide (ZnO) surge arresters. It is necessary to understand the state of ZnO surge arresters for AC traction substations under operation. The waveform distortion of leakage currents can be detected through an increase in multiple harmonic currents; therefore, this effect was employed to develop a device for diagnosing damage to the surge arrester. By adopting a Rogowski coil and band‐pass filters, we can obtain more output of the 5th–15th order harmonic currents in comparison with conventional devices. If the threshold value of harmonic elements is exceeded, the lights on the device may light up to indicate the deterioration. The validity of the device was verified by artificial deterioration tests using damaged ZnO elements and a capacitor. This developed device could indicate the soundness of the surge arresters that are in proper working order while being under the influence of feeding voltages, which include harmonic voltages.     

Development of advanced built-in surge arresters for distributionsystem with new zinc-oxide elements

New zinc-oxide elements with a varistor voltage about twice that of conventional ones have been developed by reducing the ZnO grain size with a new additive, which enables halving of the series number of elements in a metal oxide surge arrester. Using these elements, we have developed advanced built-in surge arresters enclosed in 6.6 kV pole transformers and switchgear. The advanced arresters have been reduced in volume by 25% compared with conventional ones. This paper describes the specification and construction of the advanced arresters and the results of various evaluation tests     

一种防止10 kV架空绝缘导线雷击断线用新型串联间隙金属氧化物避雷器

研制了一种由高压穿刺电极和避雷器本体构成的纯空气间隙金属氧化物避雷器。高压穿刺电极与绝缘导线穿刺接触引出高电位，当感应雷或直击雷产生足够高幅值的过电压作用于绝缘导线时，避雷器间隙击穿，避雷器本体释放雷电能量抑制工频续流起弧，达到保护绝缘导线免于断线的目的。通过对该避雷器进行大量的雷电冲击放电试验，确定了间隙距离和安装位置。     

Use of line surge arresters for the improvement of the lightningperformance of 63 kV and 90 kV shielded and unshielded transmissionlines

The lightning performance of 63 kV and 90 kV shielded and unshielded power transmission lines, protected by surge arresters are considered. A specialized software package is used for the computation of the line's fast front transients. A Monte Carlo statistical method, together with a three-dimensional electrogeometric model is used to determine the lightning stroke locations. Different arrester installation configurations are analyzed and compared. The energy duties of the transmission line surge arresters are computed statistically     

输电线路避雷器的应用及其安装方案

雷击是输电线路的主要危害。线路避雷器是降低线路雷击跳闸率的有效手段,我国已使用的线路避雷器运行情况良好。但由于线路避雷器价格昂贵,线路全线安装是不现实的,所以线路避雷器的安装地点和方式是一个比较重要的问题。本文对输电线路雷害事故及防雷措施进行了分析论述,并介绍了输电线路避雷器的发展及应用情况。最后结合我国多年的应用经验和计算分析,对于输电线路避雷器的安装方案提出了一些一般性的意见,并详细分析解释了这些意见的理由。     

Development and applications of lightning arresters fortransmission lines

A lightning arrester with a series gap for transmission lines has been developed to prevent faults due to lightning. It has shown excellent performance since 1986 on 77 kV service lines in heavy lightning regions. A 275 kV lightning arrester has also been developed, and a field test was started on a service line in 1988. The authors describe the requirements for lightning arresters for transmission lines, design concepts, specifications, and operational records on the 77 kV lines for three years. The gapped-type lightning arrester is considered the most practical given the existing technology. To obtain light and small lightning arresters, an ethylene-propylene rubber shed was adopted for external insulation and a special pressure relief mechanism was introduced in place of the pressure relief guide of the station arresters. The follow current can be cut off within a period of 0.25 to 0.5 cycles even under contaminated and wet conditions