1 引言(yan)

静电(dian)(dian)(dian)(dian)放(fang)电(dian)(dian)(dian)(dian)(esd)和(he)电(dian)(dian)(dian)(dian)快速瞬变(bian)脉冲群(eft)对(dui)变(bian)频(pin)器(qi)系统(tong)会(hui)产生(sheng)不(bu)同(tong)程度的(de)危害(hai)。当电(dian)(dian)(dian)(dian)缆暴露在(zai)4~8kv静电(dian)(dian)(dian)(dian)放(fang)电(dian)(dian)(dian)(dian)环境中时,信息传(chuan)输(shu)电(dian)(dian)(dian)(dian)缆终端负载(zai)上可以测量到的(de)感应电(dian)(dian)(dian)(dian)压(ya)可达(da)到600v,这个(ge)电(dian)(dian)(dian)(dian)压(ya)远(yuan)远(yuan)超出(chu)(chu)了变(bian)频(pin)器(qi)输(shu)入、输(shu)出(chu)(chu)端口和(he)通信端口的(de)门限电(dian)(dian)(dian)(dian)压(ya)值(zhi),典型(xing)的(de)感应脉冲持续时间大(da)约为400ns。

变(bian)(bian)(bian)频器(qi)(qi)(qi)在使用中经常(chang)会遇到意(yi)外的(de)电(dian)(dian)压(ya)(ya)瞬变(bian)(bian)(bian)和(he)(he)浪(lang)涌,从而导致变(bian)(bian)(bian)频器(qi)(qi)(qi)内部电(dian)(dian)子器(qi)(qi)(qi)件的(de)损坏(huai),损坏(huai)的(de)现(xian)象(xiang)是(shi)使变(bian)(bian)(bian)频器(qi)(qi)(qi)中的(de)半导体(ti)器(qi)(qi)(qi)件(包括(kuo)二极管、晶体(ti)管、晶闸(zha)管和(he)(he)集成(cheng)电(dian)(dian)路等(deng))被烧毁或击穿。据统计变(bian)(bian)(bian)频器(qi)(qi)(qi)控制(zhi)(zhi)部分的(de)故障有75%是(shi)由于瞬变(bian)(bian)(bian)和(he)(he)浪(lang)涌造(zao)成(cheng)的(de)。电(dian)(dian)压(ya)(ya)的(de)瞬变(bian)(bian)(bian)和(he)(he)浪(lang)涌无处不在,电(dian)(dian)网(wang)、雷击、爆破,就连(lian)人(ren)在地毯上(shang)行走都会产生(sheng)上(shang)万(wan)伏的(de)静(jing)电(dian)(dian)感应电(dian)(dian)压(ya)(ya),这些,都是(shi)变(bian)(bian)(bian)频器(qi)(qi)(qi)控制(zhi)(zhi)端(duan)口和(he)(he)通(tong)信端(duan)口的(de)隐形(xing)危(wei)害源。因此,为了(le)提高变(bian)(bian)(bian)频器(qi)(qi)(qi)的(de)可靠性就必(bi)须(xu)对电(dian)(dian)压(ya)(ya)瞬变(bian)(bian)(bian)和(he)(he)浪(lang)涌采(cai)取防护措施。

 

2 防雷端口

根据变频器(qi)应用的工程实践,变频器(qi)受雷(lei)击(ji)(ji)可(ke)大致分(fen)为直击(ji)(ji)雷(lei)、感(gan)应雷(lei)和传导雷(lei)。但不论以哪一种形式到达设备(bei)都(dou)可(ke)归纳为从以下(xia)4个部(bu)位侵入的雷(lei)电浪涌,在此把这些部(bu)位称为防雷(lei)端(duan)口,并(bing)以变频器(qi)举例说明。

 

 

2.1 外(wai)壳端口

比(bi)如(ru)(ru)说,我们(men)可以(yi)把任何(he)一个大的(de)(de)或(huo)小的(de)(de)变(bian)(bian)频器(qi)或(huo)系统视为一个整体(ti)的(de)(de)外(wai)壳(qiao),如(ru)(ru)传感器(qi)、传输线、信号(hao)中继、现场仪表(biao)、dcs系统等,它们(men)都(dou)有(you)可能完(wan)全暴露在环(huan)境中受到直接雷(lei)(lei)击(ji),造成设备(bei)损坏。标(biao)准规定,当设备(bei)外(wai)壳(qiao)受到4kv的(de)(de)雷(lei)(lei)电静电放(fang)电时,都(dou)会影响(xiang)变(bian)(bian)频器(qi)或(huo)系统的(de)(de)正常运行。例如(ru)(ru)放(fang)置于室(shi)外(wai)输入变(bian)(bian)频器(qi)的(de)(de)传感器(qi)有(you)可能受到雷(lei)(lei)电接触放(fang)电;位于室(shi)内的(de)(de)变(bian)(bian)频器(qi)柜有(you)可能受到建筑(zhu)物避雷(lei)(lei)引线泄流(liu)时的(de)(de)空间放(fang)电。

 

 

2.2 信(xin)号线端口

在变频(pin)器(qi)控制系统中,为(wei)了实现信(xin)(xin)号(hao)(hao)(hao)或(huo)(huo)信(xin)(xin)息的(de)(de)传递(di)总要有(you)与外界(jie)连(lian)接(jie)的(de)(de)部位,那(nei)么这些从(cong)外界(jie)输(shu)入信(xin)(xin)号(hao)(hao)(hao)或(huo)(huo)变频(pin)器(qi)输(shu)出的(de)(de)信(xin)(xin)号(hao)(hao)(hao)接(jie)口(kou)(kou)(kou)都(dou)有(you)可能受到(dao)雷电(dian)浪(lang)(lang)(lang)涌冲击(ji)。因为(wei)变频(pin)器(qi)柜外部信(xin)(xin)号(hao)(hao)(hao)输(shu)入变频(pin)器(qi)端(duan)(duan)口(kou)(kou)(kou)的(de)(de)浪(lang)(lang)(lang)涌往(wang)往(wang)通过长电(dian)缆(lan),所以采用10/700μs波形,标准规定线到(dao)线间(jian)浪(lang)(lang)(lang)涌电(dian)压为(wei)0.5kv,线到(dao)地(di)间(jian)浪(lang)(lang)(lang)涌电(dian)压为(wei)1kv。而楼内变频(pin)器(qi)之间(jian)传递(di)信(xin)(xin)号(hao)(hao)(hao)的(de)(de)端(duan)(duan)口(kou)(kou)(kou)受到(dao)浪(lang)(lang)(lang)涌冲击(ji)相当于电(dian)源(yuan)线上的(de)(de)浪(lang)(lang)(lang)涌冲击(ji),采用1.2/50(8/20)μs组合(he)波,线到(dao)线、线到(dao)地(di)浪(lang)(lang)(lang)涌电(dian)压限值(zhi)(zhi)不变。一旦(dan)超过限值(zhi)(zhi),信(xin)(xin)号(hao)(hao)(hao)端(duan)(duan)口(kou)(kou)(kou)和端(duan)(duan)口(kou)(kou)(kou)后的(de)(de)设备有(you)可能遭受损坏。

 

 

2.3 电源端(duan)口

电(dian)(dian)(dian)(dian)(dian)源端(duan)(duan)口是分布较广泛(fan)也较容易(yi)感应或(huo)传导(dao)雷电(dian)(dian)(dian)(dian)(dian)浪涌的(de)(de)部位(wei),变(bian)频器的(de)(de)电(dian)(dian)(dian)(dian)(dian)源端(duan)(duan)口为(wei)(wei)从(cong)配(pei)电(dian)(dian)(dian)(dian)(dian)屏(ping)到(dao)(dao)变(bian)频器电(dian)(dian)(dian)(dian)(dian)源输(shu)入端(duan)(duan)和从(cong)变(bian)频器输(shu)出(chu)端(duan)(duan)到(dao)(dao)电(dian)(dian)(dian)(dian)(dian)动机。标准规定在1.2/50(8/20)μs 波形下线与线之间浪涌电(dian)(dian)(dian)(dian)(dian)压(ya)限(xian)(xian)值为(wei)(wei)0.5kv,线到(dao)(dao)地(di)浪涌电(dian)(dian)(dian)(dian)(dian)压(ya)限(xian)(xian)制为(wei)(wei)1kv。但这(zhei)里的(de)(de)浪涌电(dian)(dian)(dian)(dian)(dian)压(ya)是指明工作电(dian)(dian)(dian)(dian)(dian)压(ya)为(wei)(wei)220v交流(liu)进入的(de)(de),如果工作电(dian)(dian)(dian)(dian)(dian)压(ya)较低则(ze)不(bu)能以此为(wei)(wei)标准,电(dian)(dian)(dian)(dian)(dian)源线上(shang)受较小的(de)(de)浪涌冲击不(bu)一定立即损坏设备,但至(zhi)少对寿命有影(ying)响。

 

 

2.4 接(jie)地端口

尽管在标准中没有(you)专门提到(dao)(dao)接(jie)(jie)(jie)(jie)(jie)地(di)端(duan)(duan)(duan)(duan)口(kou)(kou)的(de)(de)指标,实际上变频(pin)器的(de)(de)接(jie)(jie)(jie)(jie)(jie)地(di)端(duan)(duan)(duan)(duan)口(kou)(kou)是(shi)非常重要的(de)(de)。在雷(lei)电(dian)(dian)(dian)(dian)发生时接(jie)(jie)(jie)(jie)(jie)地(di)端(duan)(duan)(duan)(duan)口(kou)(kou)有(you)可(ke)能受到(dao)(dao)地(di)电(dian)(dian)(dian)(dian)位(wei)反击、地(di)电(dian)(dian)(dian)(dian)位(wei)升高影(ying)响,或者由于接(jie)(jie)(jie)(jie)(jie)地(di)不(bu)良、接(jie)(jie)(jie)(jie)(jie)地(di)不(bu)当使地(di)阻过大,达不(bu)到(dao)(dao)参(can)考(kao)电(dian)(dian)(dian)(dian)位(wei)要求使设(she)备损(sun)坏(huai)。接(jie)(jie)(jie)(jie)(jie)地(di)端(duan)(duan)(duan)(duan)口(kou)(kou)不(bu)仅(jin)对接(jie)(jie)(jie)(jie)(jie)地(di)电(dian)(dian)(dian)(dian)阻/接(jie)(jie)(jie)(jie)(jie)地(di)线(xian)极(长度(du)、直(zhi)(zhi)径、材料等)、接(jie)(jie)(jie)(jie)(jie)地(di)方(fang)式(shi)、地(di)网(wang)的(de)(de)设(she)置等有(you)要求,而且还(hai)与设(she)备的(de)(de)电(dian)(dian)(dian)(dian)特性、工(gong)作(zuo)频(pin)段、工(gong)作(zuo)环(huan)境等有(you)直(zhi)(zhi)接(jie)(jie)(jie)(jie)(jie)的(de)(de)关系。同(tong)时从接(jie)(jie)(jie)(jie)(jie)地(di)端(duan)(duan)(duan)(duan)还(hai)有(you)可(ke)能反击到(dao)(dao)变频(pin)器内的(de)(de)直(zhi)(zhi)流工(gong)作(zuo)电(dian)(dian)(dian)(dian)源(yuan)端(duan)(duan)(duan)(duan)口(kou)(kou),损(sun)坏(huai)以直(zhi)(zhi)流为工(gong)作(zuo)电(dian)(dian)(dian)(dian)压的(de)(de)单元电(dian)(dian)(dian)(dian)路。综(zong)上所述,变频(pin)器的(de)(de)防雷(lei)可(ke)以考(kao)虑从四(si)个(ge)关键的(de)(de)端(duan)(duan)(duan)(duan)口(kou)(kou)入手,如图1所示。

图1 变频器的(de)四个关键的(de)端口

3 变频器的端口保护

3.1 外壳端(duan)口

变(bian)(bian)频(pin)(pin)器(qi)的(de)外(wai)壳(qiao)(qiao)端(duan)口保(bao)护(hu)(hu)不仅仅是建筑(zhu)(zhu)物(wu)外(wai)壳(qiao)(qiao),也应(ying)当包括(kuo)变(bian)(bian)频(pin)(pin)器(qi)外(wai)壳(qiao)(qiao)或变(bian)(bian)频(pin)(pin)器(qi)柜(ju)的(de)外(wai)壳(qiao)(qiao),比如说变(bian)(bian)频(pin)(pin)器(qi)、变(bian)(bian)频(pin)(pin)器(qi)柜(ju)室等(deng)。按照iec 1312—1《雷电(dian)(dian)电(dian)(dian)磁(ci)脉冲的(de)防(fang)护(hu)(hu)》第一(yi)部分(fen)(一(yi)般原则)的(de)适用范(fan)围为(wei):建筑(zhu)(zhu)物(wu)内或建筑(zhu)(zhu)物(wu)顶(ding)部变(bian)(bian)频(pin)(pin)器(qi)系(xi)统(tong)有效的(de)雷电(dian)(dian)防(fang)护(hu)(hu)系(xi)统(tong)的(de)设计、安装、检查、维护(hu)(hu)。其保(bao)护(hu)(hu)方法主要(yao)有三种:接地、屏(ping)蔽(bi)及(ji)等(deng)电(dian)(dian)位(wei)连接。

(1) 接地

iec1024—1已经(jing)阐述了建(jian)筑物(wu)防雷接(jie)地的方法(fa),主要(yao)是通(tong)过(guo)建(jian)筑物(wu)地下网状接(jie)地系(xi)(xi)统(tong)(tong)达(da)到要(yao)求。变频器(qi)系(xi)(xi)统(tong)(tong)防雷时还要(yao)求对相邻(lin)两建(jian)筑物(wu)之(zhi)间通(tong)过(guo)的电(dian)力线(xian),信号传(chuan)输(shu)电(dian)缆均必须与建(jian)筑物(wu)接(jie)地系(xi)(xi)统(tong)(tong)连接(jie)起来(lai)(不能形(xing)成回路),以(yi)利用多条并行路径来(lai)减少(shao)电(dian)缆中的电(dian)流(liu)。

变频器(qi)系(xi)统(tong)(tong)的(de)(de)接地(di)更(geng)应当(dang)注意系(xi)统(tong)(tong)的(de)(de)安全(quan)性(xing)和防止其它系(xi)统(tong)(tong)干扰。一(yi)般来说工作状(zhuang)态下变频器(qi)系(xi)统(tong)(tong)接地(di)不能直接和防雷(lei)地(di)线相连(lian),否则将有杂(za)散电流进入变频器(qi)系(xi)统(tong)(tong)引起信号(hao)干扰。正确的(de)(de)连(lian)接方式(shi)应当(dang)在地(di)下将两(liang)个(ge)不同(tong)地(di)网(wang),通过(guo)放电器(qi)低压避雷(lei)器(qi)连(lian)接,使其在雷(lei)击状(zhuang)态下自动连(lian)通。

(2) 屏蔽

从理论上考虑(lv),屏(ping)(ping)(ping)(ping)蔽(bi)(bi)(bi)对变频(pin)(pin)器外壳防(fang)雷是非常有效的(de)。但(dan)从经济合理角(jiao)度来看,还是应当从设备(bei)元器件抗扰度及(ji)对屏(ping)(ping)(ping)(ping)蔽(bi)(bi)(bi)效能的(de)要求(qiu)来选(xuan)择不同(tong)的(de)屏(ping)(ping)(ping)(ping)蔽(bi)(bi)(bi)方(fang)法。线路屏(ping)(ping)(ping)(ping)蔽(bi)(bi)(bi),即在变频(pin)(pin)器系(xi)统(tong)中采(cai)(cai)用(yong)屏(ping)(ping)(ping)(ping)蔽(bi)(bi)(bi)电缆(lan)已被(bei)广泛应用(yong)。但(dan)对于设备(bei)或(huo)系(xi)统(tong)的(de)屏(ping)(ping)(ping)(ping)蔽(bi)(bi)(bi)需(xu)要视具(ju)体情况而定。iec提(ti)出了(le)采(cai)(cai)用(yong)建筑物(wu)钢筋连到金属(shu)框架(jia)的(de)措施举例。

iec1312—2作了如下(xia)描(miao)述:建(jian)筑物内部变频(pin)器系统(tong)的(de)(de)主要电磁干扰源是由一次闪击时(shi)的(de)(de)几个(ge)雷击的(de)(de)瞬(shun)(shun)时(shi)电流(liu)造(zao)成的(de)(de)瞬(shun)(shun)态磁场(chang)。如果包(bao)含变频(pin)器系统(tong)的(de)(de)建(jian)筑物或房间(jian)(jian),用大空(kong)间(jian)(jian)屏(ping)蔽,通(tong)常(chang)在这(zhei)样的(de)(de)措施下(xia)瞬(shun)(shun)时(shi)电场(chang)被(bei)减少到一个(ge)足够低的(de)(de)值。

(3) 等(deng)电位(wei)接连

等(deng)电(dian)(dian)(dian)(dian)位(wei)(wei)连(lian)接(jie)(jie)(jie)的(de)(de)(de)(de)目的(de)(de)(de)(de)是减小(xiao)变(bian)(bian)频器(qi)之(zhi)(zhi)间(jian)和变(bian)(bian)频器(qi)与(yu)金属部件之(zhi)(zhi)间(jian)的(de)(de)(de)(de)电(dian)(dian)(dian)(dian)位(wei)(wei)差。在防雷区的(de)(de)(de)(de)界面(mian)处的(de)(de)(de)(de)等(deng)电(dian)(dian)(dian)(dian)位(wei)(wei)连(lian)接(jie)(jie)(jie)要考(kao)虑建(jian)(jian)筑物(wu)内的(de)(de)(de)(de)变(bian)(bian)频器(qi)系(xi)统(tong)(tong),在那些对雷电(dian)(dian)(dian)(dian)电(dian)(dian)(dian)(dian)磁脉冲效应(ying)要求较小(xiao)的(de)(de)(de)(de)地(di)方,等(deng)电(dian)(dian)(dian)(dian)位(wei)(wei)连(lian)接(jie)(jie)(jie)带需要采用金属板,并多次与(yu)建(jian)(jian)筑物(wu)的(de)(de)(de)(de)钢筋连(lian)接(jie)(jie)(jie)或连(lian)接(jie)(jie)(jie)在其它屏(ping)蔽物(wu)的(de)(de)(de)(de)构件上。对于(yu)变(bian)(bian)频器(qi)系(xi)统(tong)(tong)的(de)(de)(de)(de)外露导电(dian)(dian)(dian)(dian)物(wu)应(ying)建(jian)(jian)立等(deng)位(wei)(wei)连(lian)接(jie)(jie)(jie)网(wang),原则(ze)上一个电(dian)(dian)(dian)(dian)位(wei)(wei)连(lian)接(jie)(jie)(jie)网(wang)不需要直接(jie)(jie)(jie)连(lian)在大地(di),但实(shi)际(ji)上所有(you)(you)等(deng)电(dian)(dian)(dian)(dian)位(wei)(wei)连(lian)接(jie)(jie)(jie)网(wang)都有(you)(you)通(tong)大地(di)的(de)(de)(de)(de)连(lian)接(jie)(jie)(jie)。

 

 

3.2 信号线(xian)端口

信号线端口保(bao)护(hu)现(xian)在已经在已有许多类型(xing)的较为成熟的保(bao)护(hu)器(qi)(qi)件,比(bi)如变频器(qi)(qi)信号端口保(bao)护(hu)器(qi)(qi)、变频器(qi)(qi)通信端口保(bao)护(hu)器(qi)(qi)等。在保(bao)护(hu)器(qi)(qi)选择时除了保(bao)护(hu)器(qi)(qi)本(ben)身的性(xing)能外(wai),应该(gai)注(zhu)意保(bao)护(hu)设备的传输速率、插入(ru)衰耗限值、驻波比(bi)、工作电(dian)压、工作电(dian)流等相关指标,如果在同一系统(tong)使用多级保(bao)护(hu)还应该(gai)考虑相互(hu)配合问题。

在信(xin)号(hao)端(duan)口窜入(ru)的瞬态(tai)电(dian)流比较容易损坏(huai)变频器内部的信(xin)号(hao)交换(huan)或转换(huan)单(dan)元及控制单(dan)元,如主板、并(bing)行口、信(xin)号(hao)接口卡(ka)等。事实上瞬态(tai)电(dian)流或浪涌(yong)可能(neng)通(tong)过不同途径被(bei)引(yin)入(ru)到信(xin)号(hao)传输网(wang)络中(zhong)(zhong),若变频器控制系统(tong)和上位机(ji)通(tong)信(xin)采用以太网(wang)结构,则(ze)ieee 802—3以太网(wang)标准中(zhong)(zhong)列出了四种可能(neng)对(dui)网(wang)络造成威胁的情况(kuang):

(1) 局(ju)域网络元件和供电(dian)(dian)回路(lu)或受电(dian)(dian)影响的(de)电(dian)(dian)路(lu)发生直接(jie)接(jie)触;

(2) 局(ju)域(yu)网电(dian)(dian)缆和元(yuan)件上(shang)的静电(dian)(dian)效果;

(3) 高能量瞬态电(dian)流同局域网络系统耦合(由(you)网络电(dian)缆附近的电(dian)缆引入);

(4) 彼此相连的网络(luo)元件的地线(xian)电压间有细小差别(例如两幢(chuang)不同建筑的安全地线(xian)电压就有可能略有不同)。

以变频器通信(xin)(xin)线为(wei)例,在rs-232的(de)串(chuan)、并行口(kou)的(de)标准(zhun)中(zhong),用于(yu)泄(xie)放(fang)高(gao)能(neng)浪涌(yong)和故障电流的(de)地线同数据(ju)信(xin)(xin)号的(de)返回路径共享一(yi)条线路,而(er)(er)小至(zhi)几十伏的(de)瞬(shun)态(tai)电压都有可能(neng)通过这些(xie)串(chuan)、并行口(kou)而(er)(er)毁坏上(shang)位机及终端等设(she)备,信(xin)(xin)号传(chuan)(chuan)输线也能(neng)直接(jie)将户外电源(yuan)线上(shang)的(de)瞬(shun)态(tai)浪涌(yong)传(chuan)(chuan)导(dao)进来(lai),而(er)(er)信(xin)(xin)号接(jie)口(kou)能(neng)够(gou)传(chuan)(chuan)导(dao)由闪电和静电泄(xie)漏引起(qi)的(de)浪涌(yong)电压。

用(yong)户应(ying)当对(dui)数(shu)据(ju)(ju)线保(bao)(bao)(bao)护(hu)(hu)器(qi)(qi)慎重选择,有(you)些保(bao)(bao)(bao)护(hu)(hu)器(qi)(qi)虽然起到了“分流”作用(yong),但(dan)常常是(shi)将(jiang)硅雪崩二(er)极管(sad)接在被保(bao)(bao)(bao)护(hu)(hu)线路和保(bao)(bao)(bao)护(hu)(hu)器(qi)(qi)外壳(qiao)之间,测试(shi)表明sad的箝位性(xing)能很好,但(dan)它(ta)电(dian)涌分流能力有(you)限(xian)。同时压(ya)敏电(dian)阻(mov)也不能在数(shu)据(ju)(ju)线保(bao)(bao)(bao)护(hu)(hu)器(qi)(qi)上使用(yong)。先进(jin)的过程控制系(xi)统的信号接口防雷保(bao)(bao)(bao)护(hu)(hu)装置(无论是(shi)rs-232串等(deng)通信接口还是(shi)计(ji)算机同轴网络适(shi)配器(qi)(qi)接口)目前(qian)均采用(yong)瞬态(tai)过电(dian)压(ya)半导体放电(dian)管,其(qi)冲击残压(ya)参数(shu)指标很重要。有(you)条件时能够采取(qu)多级保(bao)(bao)(bao)护(hu)(hu)设计(ji)电(dian)路效(xiao)果更佳。

 

 

3.3 电源(yuan)端口

原(yuan)则(ze)上采用多(duo)级spd做电(dian)(dian)(dian)源保护,但变(bian)频器(qi)控制系(xi)统(tong)(tong)的(de)(de)(de)电(dian)(dian)(dian)源保护由于(yu)其敏感性必须采用较低(di)的(de)(de)(de)残压(ya)值的(de)(de)(de)保护器(qi)件,且此残压(ya)应当低(di)于(yu)需要保护设备的(de)(de)(de)耐压(ya)能力。同时还(hai)必须考虑到电(dian)(dian)(dian)磁干扰对变(bian)频器(qi)系(xi)统(tong)(tong)的(de)(de)(de)影(ying)响,因此带滤波的(de)(de)(de)分流设计应当更加理想。所以(yi)对于(yu)变(bian)频器(qi)系(xi)统(tong)(tong)电(dian)(dian)(dian)源保护特别(bie)注意(yi)的(de)(de)(de)两点是:前两级采用通流容量(liang)大的(de)(de)(de)保护器(qi),在变(bian)频器(qi)终端处则(ze)采用残压(ya)较低(di)的(de)(de)(de)保护器(qi)。在保护器(qi)中需要有滤波电(dian)(dian)(dian)路。对变(bian)频器(qi)系(xi)统(tong)(tong)电(dian)(dian)(dian)源端口安(an)装spd时应注意(yi)以(yi)下(xia)问(wen)题:

(1) 多级spd应(ying)当考(kao)虑能(neng)量配(pei)合(he)(he)、时间配(pei)合(he)(he)、距离配(pei)合(he)(he)。如(ru)果(guo)配(pei)合(he)(he)不当的话(hua),效果(guo)将(jiang)适得其反。

(2) 连接防雷保护器(qi)的引线应当尽量粗(cu)和短(duan)。

(3) 全保护时尽(jin)可(ke)能将所有(you)连接线捆(kun)扎在一起。

 

4 结(jie)束语

变(bian)频调速传(chuan)动系(xi)统中,重视(shi)变(bian)频器(qi)的(de)的(de)端(duan)(duan)口(kou)(kou)防(fang)(fang)护,已(yi)成(cheng)为变(bian)频变(bian)频调速传(chuan)动系(xi)统设计(ji)、应用(yong)必须(xu)面对的(de)问(wen)(wen)题,也(ye)是变(bian)频器(qi)应用(yong)和(he)推广的(de)关(guan)键问(wen)(wen)题之一。变(bian)频器(qi)的(de)端(duan)(duan)口(kou)(kou)防(fang)(fang)护问(wen)(wen)题一定(ding)会不(bu)断发(fa)展(zhan)和(he)完善。


2017年07月27日(ri)

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变频系统的端口防护技术

静电放电(esd)和电快速瞬变脉冲群(eft)对变频器系统会产生不同程度的危害。当电缆暴露在4~8kv静电放电环境中时,信息传输电缆终端负载上可以测量到的感应电压可达到600v,这个电压远远超出了变频器输入、输出端口和通信端口的门限电压值,典型的感应脉冲持续时间大约为400ns。

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