摘要:绝(jue)(jue)缘配(pei)合(he)(he)问题是一个关(guan)系(xi)到(dao)电(dian)(dian)气设(she)(she)备产(chan)品(pin)安全性的(de)重(zhong)要问题,历来(lai)受到(dao)来(lai)自各方面的(de)重(zhong)视。绝(jue)(jue)缘配(pei)合(he)(he)最早应用在(zai)高压电(dian)(dian)器(qi)产(chan)品(pin)中(zhong)(zhong)。我国的(de)电(dian)(dian)器(qi)产(chan)品(pin)中(zhong)(zhong),由于绝(jue)(jue)缘系(xi)统而引发的(de)事故占50%-60%,又由于在(zai)低压成(cheng)套开关(guan)设(she)(she)备和控(kong)制设(she)(she)备中(zhong)(zhong)正式引用绝(jue)(jue)缘配(pei)合(he)(he)这个概(gai)念(nian),只是近两年的(de)事情。所以,正确(que)处理、解决好产(chan)品(pin)中(zhong)(zhong)绝(jue)(jue)缘配(pei)合(he)(he)问题,是一个比较重(zhong)要的(de)问题,应该给予足够的(de)重(zhong)视。
关(guan)键词:低压开关(guan)设(she)备 绝(jue)缘(yuan)配合(he) 绝(jue)缘(yuan)材料(liao)
0 引言
低压成(cheng)套开关(guan)(guan)设(she)(she)备(bei)(bei)(bei)在(zai)低压供(gong)电系统中负责电能(neng)(neng)的(de)(de)(de)控制、保护、测量、转换和分配。由于(yu)低压成(cheng)套开关(guan)(guan)设(she)(she)备(bei)(bei)(bei)深入到生(sheng)产现场(chang)(chang)、公(gong)共场(chang)(chang)所(suo)、居民住宅等地点,可以说凡是使用(yong)电气设(she)(she)备(bei)(bei)(bei)的(de)(de)(de)地方都应配备(bei)(bei)(bei)低压设(she)(she)备(bei)(bei)(bei),我(wo)国电能(neng)(neng)的(de)(de)(de)80%左(zuo)右都是通过低压成(cheng)套开关(guan)(guan)设(she)(she)备(bei)(bei)(bei)供(gong)出,低压成(cheng)套开关(guan)(guan)设(she)(she)备(bei)(bei)(bei)的(de)(de)(de)发展(zhan)源于(yu)材(cai)料工业、低压电器、加(jia)工工艺(yi)和设(she)(she)备(bei)(bei)(bei)、基础设(she)(she)施建设(she)(she)和人民的(de)(de)(de)生(sheng)活(huo)水平(ping),所(suo)以低压成(cheng)套开关(guan)(guan)设(she)(she)备(bei)(bei)(bei)的(de)(de)(de)水平(ping)从(cong)一个(ge)侧面(mian)反映(ying)了一个(ge)国家(jia)的(de)(de)(de)经济(ji)实(shi)力与科学(xue)技术、生(sheng)活(huo)水平(ping)。
1 绝(jue)缘配合的基本原理
绝(jue)(jue)(jue)(jue)缘(yuan)(yuan)配合意(yi)指根据设(she)备(bei)的(de)(de)使用(yong)条件及周围(wei)环境(jing)来(lai)选择设(she)备(bei)的(de)(de)电气绝(jue)(jue)(jue)(jue)缘(yuan)(yuan)特性,只有在设(she)备(bei)的(de)(de)设(she)计基于其期望寿命中所承受的(de)(de)作用(yong)强度时,才能实现绝(jue)(jue)(jue)(jue)缘(yuan)(yuan)配合。绝(jue)(jue)(jue)(jue)缘(yuan)(yuan)配合的(de)(de)问(wen)题不仅来(lai)自设(she)备(bei)外部而且(qie)还(hai)来(lai)自设(she)备(bei)本身,是(shi)一(yi)个涉及各方(fang)面因素,须加以综合考(kao)虑的(de)(de)问(wen)题,其要(yao)点分(fen)为三部分(fen):一(yi)是(shi)设(she)备(bei)的(de)(de)使用(yong)条件;二是(shi)设(she)备(bei)的(de)(de)使用(yong)环境(jing),三是(shi)绝(jue)(jue)(jue)(jue)缘(yuan)(yuan)材料的(de)(de)选用(yong)。
1.1 设备(bei)的(de)使(shi)用条件 设备(bei)的(de)使(shi)用条件主要指设备(bei)使(shi)用的(de)电压、电场、频率。
1.1.1 绝(jue)缘配(pei)合与(yu)电(dian)压(ya)(ya)的关系。在考(kao)虑(lv)绝(jue)缘配(pei)合与(yu)电(dian)压(ya)(ya)的关系中(zhong),要考(kao)虑(lv)在系统中(zhong)可能出现的电(dian)压(ya)(ya)、设(she)备产(chan)生(sheng)的电(dian)压(ya)(ya),要求的持续电(dian)压(ya)(ya)运行等级,以及人身安(an)全、事(shi)故的危险性。
①电压(ya)与过电压(ya)的(de)分类,波形。
a持(chi)续工(gong)频电(dian)压,有着恒定r、m、s的电(dian)压;
b暂时过电压,较长持续时间的工频过电压;
c瞬态过电(dian)压,几毫秒或(huo)更短的持(chi)续(xu)时间的过电(dian)压,通常是高阻尼的振荡或(huo)非(fei)振荡的。
——缓(huan)波前过(guo)电压(ya):一种瞬态(tai)过(guo)电压(ya),通常是单(dan)方向(xiang)的,到达(da)峰值的时(shi)间为20μsTp5000μs之间,波尾持(chi)续(xu)时(shi)间T2≤20ms。
——快(kuai)波前过电压:一种瞬态(tai)过电压,通常是单方向的,到达峰(feng)值(zhi)时(shi)(shi)间为0.1μsT120μs,波尾持(chi)续时(shi)(shi)间T2≤300μs。
——陡波前过(guo)电压:一种(zhong)瞬态过(guo)电压,通常是单方向的,到达峰(feng)值的时间为Tf≤0.1μs,总持(chi)续时间3ms,并(bing)带有叠加(jia)振(zhen)荡(dang),振(zhen)荡(dang)频(pin)率地30kHzf100MHz之间。
d联合(暂(zan)时(shi)、缓(huan)前波、快波前、陡波前)过电压。
根据上(shang)述(shu)的过电压类型(xing),可描述(shu)出标准的电压波形。
②长(zhang)期的(de)交流或直(zhi)流电(dian)(dian)(dian)压与绝(jue)(jue)缘配(pei)合的(de)关系,要(yao)(yao)考虑(lv)额(e)定(ding)(ding)电(dian)(dian)(dian)压、额(e)定(ding)(ding)绝(jue)(jue)缘电(dian)(dian)(dian)压、实际工(gong)作电(dian)(dian)(dian)压。在系统正常、长(zhang)期运行过程中,主要(yao)(yao)要(yao)(yao)考虑(lv)额(e)定(ding)(ding)的(de)绝(jue)(jue)缘电(dian)(dian)(dian)压和实际工(gong)作电(dian)(dian)(dian)压,而这(zhei)一点除(chu)了要(yao)(yao)满足标准的(de)要(yao)(yao)求外(wai),更(geng)要(yao)(yao)注意考虑(lv)我(wo)国电(dian)(dian)(dian)网(wang)的(de)实际情(qing)况(kuang)。在目(mu)前我(wo)国电(dian)(dian)(dian)网(wang)质量尚(shang)不高的(de)情(qing)况(kuang)下,设计(ji)产品时(shi),对绝(jue)(jue)缘配(pei)合而言,实际可能出现的(de)工(gong)作电(dian)(dian)(dian)压更(geng)重要(yao)(yao)。
③瞬态过(guo)(guo)电(dian)(dian)(dian)压(ya)与绝缘配合的(de)(de)(de)关系(xi),这(zhei)与电(dian)(dian)(dian)气(qi)系(xi)统(tong)(tong)内被控过(guo)(guo)电(dian)(dian)(dian)压(ya)的(de)(de)(de)条件有关。在(zai)系(xi)统(tong)(tong)和设(she)备(bei)中(zhong),存在(zai)多(duo)种(zhong)形式的(de)(de)(de)过(guo)(guo)电(dian)(dian)(dian)压(ya),要全面考虑各种(zhong)过(guo)(guo)电(dian)(dian)(dian)压(ya)的(de)(de)(de)影响(xiang),在(zai)低压(ya)电(dian)(dian)(dian)力系(xi)统(tong)(tong)中(zhong),过(guo)(guo)电(dian)(dian)(dian)压(ya)可(ke)能会(hui)受到各种(zhong)多(duo)变因素的(de)(de)(de)影响(xiang),所以,系(xi)统(tong)(tong)中(zhong)的(de)(de)(de)过(guo)(guo)电(dian)(dian)(dian)压(ya)的(de)(de)(de)是通(tong)过(guo)(guo)统(tong)(tong)计(ji)的(de)(de)(de)方法来评定,反(fan)映了一(yi)种(zhong)发生概(gai)(gai)率的(de)(de)(de)概(gai)(gai)念,并可(ke)通(tong)过(guo)(guo)概(gai)(gai)率统(tong)(tong)计(ji)的(de)(de)(de)方法来决定是否(fou)需要保护(hu)控制。
1.1.2 设(she)备(bei)(bei)(bei)的(de)(de)(de)(de)过电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)压(ya)(ya)类(lei)别(bie) 根据(ju)设(she)备(bei)(bei)(bei)的(de)(de)(de)(de)使(shi)用(yong)(yong)(yong)条件,要求(qiu)的(de)(de)(de)(de)长期持续电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)压(ya)(ya)运行等(deng)级(ji)(ji),将直(zhi)接由低压(ya)(ya)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)网(wang)供电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)设(she)备(bei)(bei)(bei)的(de)(de)(de)(de)过电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)压(ya)(ya)类(lei)别(bie)分为Ⅳ级(ji)(ji)。过电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)压(ya)(ya)类(lei)别(bie)Ⅳ级(ji)(ji)的(de)(de)(de)(de)设(she)备(bei)(bei)(bei)是使(shi)用(yong)(yong)(yong)在(zai)配电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)装置(zhi)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源端的(de)(de)(de)(de)设(she)备(bei)(bei)(bei),如(ru)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)表和(he)前级(ji)(ji)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流保护(hu)设(she)备(bei)(bei)(bei)。过电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)压(ya)(ya)类(lei)别(bie)Ⅲ级(ji)(ji)的(de)(de)(de)(de)设(she)备(bei)(bei)(bei)是安装在(zai)配电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)装置(zhi)中的(de)(de)(de)(de)任务,以及设(she)备(bei)(bei)(bei)的(de)(de)(de)(de)使(shi)用(yong)(yong)(yong)安全性和(he)适用(yong)(yong)(yong)性必须(xu)符合特殊要求(qiu)者(zhe),如(ru)配电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)装置(zhi)中的(de)(de)(de)(de)开关电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)器。过电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)压(ya)(ya)类(lei)别(bie)Ⅱ级(ji)(ji)的(de)(de)(de)(de)设(she)备(bei)(bei)(bei)是由配电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)装置(zhi)供电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)的(de)(de)(de)(de)耗能设(she)备(bei)(bei)(bei),如(ru)家(jia)用(yong)(yong)(yong)和(he)类(lei)似用(yong)(yong)(yong)途的(de)(de)(de)(de)负载。过电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)压(ya)(ya)类(lei)别(bie)Ⅰ级(ji)(ji)的(de)(de)(de)(de)设(she)备(bei)(bei)(bei)是连接在(zai)将瞬(shun)态(tai)过电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)压(ya)(ya)限制(zhi)在(zai)相当低水平(ping)的(de)(de)(de)(de)设(she)备(bei)(bei)(bei),如(ru)具有过压(ya)(ya)保护(hu)的(de)(de)(de)(de)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)子电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路上(shang)。对于不直(zhi)接由低压(ya)(ya)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)网(wang)供电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)的(de)(de)(de)(de)设(she)备(bei)(bei)(bei),必须(xu)考虑(lv)到系(xi)统设(she)备(bei)(bei)(bei)可能出现(xian)的(de)(de)(de)(de)最高电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)压(ya)(ya)及各种情况(kuang)的(de)(de)(de)(de)严重组合。
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电场(chang)情况分为(wei)均(jun)匀(yun)电场(chang)与非(fei)(fei)均(jun)匀(yun)电场(chang),在低(di)压(ya)成套开关设备中(zhong),一般认(ren)为(wei)是处(chu)在非(fei)(fei)均(jun)匀(yun)电场(chang)情况下,关于频率问题,目(mu)前尚在考虑中(zhong),一般认(ren)为(wei)低(di)频对绝缘(yuan)配(pei)合影(ying)响(xiang)不大,但高频还是有影(ying)响(xiang)的,尤(you)其是对绝缘(yuan)材料。
1.2 绝缘(yuan)配(pei)合(he)与环(huan)(huan)境(jing)条件的(de)(de)关系 设(she)备所处的(de)(de)宏观(guan)环(huan)(huan)境(jing)影响(xiang)着绝缘(yuan)配(pei)合(he),从(cong)目前实际应用与标准(zhun)的(de)(de)要求来看,气(qi)压(ya)的(de)(de)变(bian)化只考(kao)虑到海拔高度引起的(de)(de)气(qi)压(ya)的(de)(de)变(bian)化,日(ri)常的(de)(de)气(qi)压(ya)变(bian)化已经忽略,温度与湿度的(de)(de)因素(su)也已忽略,但如果有(you)更精确(que)的(de)(de)要求时(shi),这(zhei)些(xie)因素(su)也还是应予(yu)以(yi)考(kao)虑。从(cong)微(wei)(wei)(wei)(wei)观(guan)环(huan)(huan)境(jing)上(shang)讲,宏观(guan)环(huan)(huan)境(jing)决定了微(wei)(wei)(wei)(wei)观(guan)环(huan)(huan)境(jing),但微(wei)(wei)(wei)(wei)观(guan)环(huan)(huan)境(jing)有(you)可能会好于或坏于宏观(guan)环(huan)(huan)境(jing)设(she)备,外壳不(bu)同(tong)的(de)(de)防护等级(ji)、加热(re)、通风、灰尘都(dou)有(you)可能影响(xiang)微(wei)(wei)(wei)(wei)观(guan)环(huan)(huan)境(jing),微(wei)(wei)(wei)(wei)观(guan)环(huan)(huan)境(jing)在相关标准(zhun)有(you)明确(que)规定,这(zhei)就为(wei)产品的(de)(de)设(she)计提供了依(yi)据。
1.3 绝(jue)(jue)(jue)缘(yuan)配合与(yu)绝(jue)(jue)(jue)缘(yuan)材(cai)(cai)料(liao)(liao) 绝(jue)(jue)(jue)缘(yuan)材(cai)(cai)料(liao)(liao)的(de)(de)(de)问题相当复杂,它不同于(yu)气体(ti),是(shi)一(yi)种一(yi)旦(dan)遭到破坏(huai)(huai)便不可恢(hui)复的(de)(de)(de)绝(jue)(jue)(jue)缘(yuan)介质(zhi),即使偶然发生(sheng)的(de)(de)(de)过(guo)电压事件也有可能造成永久损坏(huai)(huai),绝(jue)(jue)(jue)缘(yuan)材(cai)(cai)料(liao)(liao)在长期的(de)(de)(de)使用中,会遇到各(ge)种各(ge)样情况,如放电事故等(deng),而(er)绝(jue)(jue)(jue)缘(yuan)材(cai)(cai)料(liao)(liao)本身(shen)由(you)(you)于(yu)长期积累的(de)(de)(de)各(ge)种因素,如热应(ying)(ying)力、温度(du)(du),机(ji)械冲击等(deng)应(ying)(ying)力,又会加速(su)它的(de)(de)(de)老化过(guo)程。对于(yu)绝(jue)(jue)(jue)缘(yuan)材(cai)(cai)料(liao)(liao)来(lai)讲,由(you)(you)于(yu)品种的(de)(de)(de)多样性(xing)(xing),其(qi)衡量绝(jue)(jue)(jue)缘(yuan)材(cai)(cai)料(liao)(liao)的(de)(de)(de)特性(xing)(xing)指(zhi)标虽多,但不统一(yi)。这就为绝(jue)(jue)(jue)缘(yuan)材(cai)(cai)料(liao)(liao)的(de)(de)(de)选择和(he)使用带来(lai)一(yi)定难度(du)(du),这也就是(shi)目前从(cong)国际上(shang)对绝(jue)(jue)(jue)缘(yuan)材(cai)(cai)料(liao)(liao)的(de)(de)(de)其(qi)它特性(xing)(xing),如热应(ying)(ying)力、机(ji)械特性(xing)(xing)、局部放电等(deng)指(zhi)标暂(zan)不予以考虑的(de)(de)(de)原因。
2 绝缘配合的验证
目前验证绝缘(yuan)配(pei)合的(de)优(you)选方法是使用冲(chong)击介电试验来进行,对于不同设备可选定不同额定冲(chong)击电压(ya)值。
2.1 用额定(ding)(ding)冲(chong)击电压(ya)试(shi)验验证设备的(de)(de)绝缘配合 额定(ding)(ding)冲(chong)击电压(ya)的(de)(de)为1.2/50μs的(de)(de)波形(xing)。
用(yong)此(ci)波形来模(mo)拟(ni)瞬态(tai)过电(dian)(dian)压(ya)、大气(qi)过电(dian)(dian)压(ya),同时(shi)也(ye)包(bao)括低压(ya)设(she)(she)备(bei)的(de)(de)(de)(de)接通分断(duan)所(suo)产生(sheng)的(de)(de)(de)(de)过电(dian)(dian)压(ya),冲击(ji)试验电(dian)(dian)源(yuan)脉冲波形发生(sheng)器其输(shu)出(chu)阻抗(kang)一般应(ying)大于500Ω,额定冲击(ji)电(dian)(dian)压(ya)值(zhi)的(de)(de)(de)(de)确(que)定,应(ying)根(gen)据(ju)设(she)(she)备(bei)的(de)(de)(de)(de)使用(yong)场合,过电(dian)(dian)压(ya)类别和设(she)(she)备(bei)的(de)(de)(de)(de)长期(qi)使用(yong)电(dian)(dian)压(ya)来决定,并应(ying)根(gen)据(ju)相应(ying)的(de)(de)(de)(de)海拔高度(du)(du)进(jin)行修正。目前低压(ya)成(cheng)套(tao)开关(guan)设(she)(she)备(bei)对某些试验条件。如(ru)湿度(du)(du)、温度(du)(du)没(mei)有作出(chu)明确(que)的(de)(de)(de)(de)规(gui)定,但(dan)也(ye)应(ying)该(gai)在成(cheng)套(tao)开关(guan)设(she)(she)备(bei)标准适用(yong)范(fan)围内,如(ru)设(she)(she)备(bei)的(de)(de)(de)(de)使用(yong)环境超出(chu)了成(cheng)套(tao)开关(guan)设(she)(she)备(bei)的(de)(de)(de)(de)适用(yong)范(fan)围,则必(bi)须予以考虑修正。气(qi)压(ya)与温度(du)(du)的(de)(de)(de)(de)修正关(guan)系如(ru)下式:
K=P/101.3×293(ΔT+293)
K——气压(ya)与温度的修正参数(shu)
ΔT——实(shi)际(试验室)温度与T=20℃的温差K
P——实际气压kPa
2.2 替代冲击(ji)电压(ya)的介电试(shi)(shi)验(yan)(yan) 对(dui)于低(di)压(ya)成套(tao)开关设(she)备可以用交流或直流试(shi)(shi)验(yan)(yan)来替代冲击(ji)电压(ya)试(shi)(shi)验(yan)(yan),但是这类(lei)试(shi)(shi)验(yan)(yan)方法比冲击(ji)电压(ya)试(shi)(shi)验(yan)(yan)要(yao)严(yan)酷,应(ying)征得制(zhi)造厂的同意。
交流试(shi)验,在交流情况下(xia),持续时(shi)间为3个周波。
直(zhi)流试验,每相(正、负极)各施加电压三次,每次持续时间为10ms。
就(jiu)目前我国的实际情况而言,在(zai)高、低(di)压(ya)电器产品(pin)中(zhong),设备的绝(jue)缘(yuan)(yuan)配(pei)(pei)合(he)仍是一个较(jiao)(jiao)大的问题,又由于在(zai)低(di)压(ya)成套(tao)开关设备和控制设备中(zhong)正(zheng)式引用绝(jue)缘(yuan)(yuan)配(pei)(pei)合(he)这个概(gai)念(nian),只是近(jin)两年的事(shi)情。所(suo)以,正(zheng)确处理(li)、解决(jue)好产品(pin)中(zhong)绝(jue)缘(yuan)(yuan)配(pei)(pei)合(he)问题,是一个比较(jiao)(jiao)重要的问题。
参考文献:
[1]IEC439-1低压成套(tao)开关设(she)备和(he)(he)控制(zhi)设(she)备第一部分:型(xing)(xing)式(shi)试验(yan)和(he)(he)部分型(xing)(xing)式(shi)试验(yan)成套(tao)设(she)备[S].
IEC890用外推法检查低压(ya)成(cheng)(cheng)套开(kai)关设(she)备和(he)控制设(she)备通过部(bu)分(fen)型式试验成(cheng)(cheng)套设(she)备的温升[S].
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