東莞市德爾創電(dian)子有限公司

壓敏(min)電(dian)(dian)阻(zu)(zu)器(qi)(qi)的(de)電(dian)(dian)阻(zu)(zu)體材料是(shi)半(ban)導體，所以(yi)它(ta)是(shi)半(ban)導體電(dian)(dian)阻(zu)(zu)器(qi)(qi)的(de)一個品(pin)種。現在大量使用的(de)"氧化鋅"(ZnO)壓敏(min)電(dian)(dian)阻(zu)(zu)器(qi)(qi)，它(ta)的(de)主體材料有(you)二價(jia)元素(Zn)和六價(jia)元素氧(O)所構成(cheng)。所以(yi)從材料的(de)角(jiao)度來看，氧化鋅壓敏(min)電(dian)(dian)阻(zu)(zu)器(qi)(qi)是(shi)一種“Ⅱ-Ⅵ族氧化物半(ban)導體”。
　　對于我們(men)設(she)備中使(shi)用的壓(ya)敏電(dian)阻，原(yuan)選(xuan)用型號(hao)(hao)為(wei)14D101K，實際運行3個(ge)月(yue)中，此型號(hao)(hao)壓(ya)敏電(dian)阻經常燒毀(hui)。后改(gai)為(wei)14D121K，實際運行3個(ge)月(yue)，沒有發(fa)現燒壞。所以(yi)，為(wei)指導以(yi)后工(gong)作，整理(li)并(bing)學(xue)習此資(zi)料，并(bing)在整理(li)過程中，發(fa)現壓(ya)敏電(dian)阻不應該直(zhi)接并(bing)接在元件(jian)的輸入端(duan)。具體壓(ya)敏電(dian)阻的資(zi)料如下：
　　一、壓(ya)敏電阻的原理
　　壓(ya)敏電(dian)(dian)阻意思是“在(zai)一(yi)定電(dian)(dian)流電(dian)(dian)壓(ya)范圍內電(dian)(dian)阻值隨電(dian)(dian)壓(ya)而變”，或者(zhe)是說“電(dian)(dian)阻值對電(dian)(dian)壓(ya)敏感”的阻器。相應(ying)的英文名稱叫“VoltageDependentResistor”簡寫(xie)為“VDR”。
　　隨著加在它(ta)上面的(de)(de)電(dian)(dian)(dian)壓(ya)(ya)(ya)不斷增大(da)(da)，它(ta)的(de)(de)電(dian)(dian)(dian)阻(zu)(zu)值可以從MΩ(兆歐)級變(bian)(bian)到mΩ(毫歐)級。當(dang)電(dian)(dian)(dian)壓(ya)(ya)(ya)較低時(shi)，壓(ya)(ya)(ya)敏電(dian)(dian)(dian)阻(zu)(zu)工作于漏(lou)電(dian)(dian)(dian)流(liu)區(qu)(qu)，呈(cheng)(cheng)現很(hen)大(da)(da)的(de)(de)電(dian)(dian)(dian)阻(zu)(zu)，漏(lou)電(dian)(dian)(dian)流(liu)很(hen)小(xiao)；當(dang)電(dian)(dian)(dian)壓(ya)(ya)(ya)升(sheng)(sheng)高(gao)進(jin)入(ru)非線(xian)性區(qu)(qu)后，電(dian)(dian)(dian)流(liu)在相(xiang)當(dang)大(da)(da)的(de)(de)范圍內變(bian)(bian)化時(shi)，電(dian)(dian)(dian)壓(ya)(ya)(ya)變(bian)(bian)化不大(da)(da)，呈(cheng)(cheng)現較好的(de)(de)限壓(ya)(ya)(ya)特性；電(dian)(dian)(dian)壓(ya)(ya)(ya)再升(sheng)(sheng)高(gao)，壓(ya)(ya)(ya)敏電(dian)(dian)(dian)阻(zu)(zu)進(jin)入(ru)飽和區(qu)(qu)，呈(cheng)(cheng)現一(yi)個(ge)很(hen)小(xiao)的(de)(de)線(xian)性電(dian)(dian)(dian)阻(zu)(zu)，由于電(dian)(dian)(dian)流(liu)很(hen)大(da)(da)，時(shi)間一(yi)長就(jiu)會使壓(ya)(ya)(ya)敏電(dian)(dian)(dian)阻(zu)(zu)過熱(re)燒毀甚至炸(zha)裂。正常使用時(shi)壓(ya)(ya)(ya)敏電(dian)(dian)(dian)阻(zu)(zu)處(chu)于漏(lou)電(dian)(dian)(dian)流(liu)區(qu)(qu)，受(shou)到浪涌沖擊(ji)時(shi)進(jin)入(ru)非線(xian)性區(qu)(qu)泄放浪涌電(dian)(dian)(dian)流(liu)，一(yi)般不能(neng)進(jin)入(ru)飽和區(qu)(qu)
　　壓(ya)敏電(dian)阻(zu)器(qi)的(de)(de)電(dian)阻(zu)體(ti)材料是半導(dao)體(ti)，所以(yi)它是半導(dao)體(ti)電(dian)阻(zu)器(qi)的(de)(de)一個品(pin)種(zhong)。現在(zai)大量使用的(de)(de)"氧(yang)(yang)化鋅"(ZnO)壓(ya)敏電(dian)阻(zu)器(qi)，它的(de)(de)主體(ti)材料有二價元(yuan)素(Zn)和六價元(yuan)素氧(yang)(yang)(O)所構成(cheng)。所以(yi)從材料的(de)(de)角度來看，氧(yang)(yang)化鋅壓(ya)敏電(dian)阻(zu)器(qi)是一種(zhong)“Ⅱ-Ⅵ族氧(yang)(yang)化物半導(dao)體(ti)”。
　　二、壓敏(min)電阻的作用
　　壓(ya)敏電(dian)(dian)(dian)阻的(de)最大特點是(shi)當(dang)加在它(ta)上面的(de)電(dian)(dian)(dian)壓(ya)低(di)于它(ta)的(de)閥值(zhi)"UN"時，流(liu)(liu)(liu)過(guo)它(ta)的(de)電(dian)(dian)(dian)流(liu)(liu)(liu)極(ji)小，相(xiang)當(dang)于一只關死的(de)閥門，當(dang)電(dian)(dian)(dian)壓(ya)超過(guo)UN時，流(liu)(liu)(liu)過(guo)它(ta)的(de)電(dian)(dian)(dian)流(liu)(liu)(liu)激增，相(xiang)當(dang)于閥門打(da)開(kai)。利(li)用這(zhe)一功能，可以抑制電(dian)(dian)(dian)路(lu)中(zhong)經常出(chu)現的(de)異常過(guo)電(dian)(dian)(dian)壓(ya)，保護(hu)電(dian)(dian)(dian)路(lu)免受過(guo)電(dian)(dian)(dian)壓(ya)的(de)損害(hai)。
　　壓(ya)(ya)(ya)(ya)敏(min)(min)電(dian)(dian)阻(zu)器(qi)是一種(zhong)具有瞬(shun)態(tai)電(dian)(dian)壓(ya)(ya)(ya)(ya)抑制功能的(de)元(yuan)件，可(ke)以用來代(dai)替瞬(shun)態(tai)抑制二極管(guan)、齊(qi)納二極管(guan)和電(dian)(dian)容(rong)器(qi)的(de)組合。壓(ya)(ya)(ya)(ya)敏(min)(min)電(dian)(dian)阻(zu)器(qi)可(ke)以對IC及(ji)其它設(she)備的(de)電(dian)(dian)路(lu)進行(xing)保護，防止因(yin)靜(jing)電(dian)(dian)放電(dian)(dian)、浪涌及(ji)其它瞬(shun)態(tai)電(dian)(dian)流(liu)(如雷擊等)而(er)造成對它們的(de)損壞(huai)。使用時(shi)(shi)只需將壓(ya)(ya)(ya)(ya)敏(min)(min)電(dian)(dian)阻(zu)器(qi)并接于被(bei)保護的(de)IC或(huo)設(she)備電(dian)(dian)路(lu)上，當電(dian)(dian)壓(ya)(ya)(ya)(ya)瞬(shun)間高于某(mou)一數值時(shi)(shi)，壓(ya)(ya)(ya)(ya)敏(min)(min)電(dian)(dian)阻(zu)器(qi)阻(zu)值迅速下降，導(dao)通(tong)大電(dian)(dian)流(liu)，從而(er)保護IC或(huo)電(dian)(dian)器(qi)設(she)備；當電(dian)(dian)壓(ya)(ya)(ya)(ya)低于壓(ya)(ya)(ya)(ya)敏(min)(min)電(dian)(dian)阻(zu)器(qi)工(gong)作(zuo)電(dian)(dian)壓(ya)(ya)(ya)(ya)值時(shi)(shi)，壓(ya)(ya)(ya)(ya)敏(min)(min)電(dian)(dian)阻(zu)器(qi)阻(zu)值極高，近乎(hu)開路(lu)，因(yin)而(er)不會影響器(qi)件或(huo)電(dian)(dian)器(qi)設(she)備的(de)正常(chang)工(gong)作(zuo)。
　　三、壓(ya)敏(min)電阻(zu)的標(biao)稱參數
　　壓(ya)敏電(dian)(dian)阻用(yong)字(zi)母(mu)“MY”表示，如加J為家用(yong)，后面的字(zi)母(mu)W、G、P、L、H、Z、B、C、N、K分別用(yong)于穩壓(ya)、過(guo)壓(ya)保護(hu)(hu)、高(gao)頻電(dian)(dian)路、防雷、滅弧(hu)、消噪(zao)、補償、消磁、高(gao)能(neng)或(huo)高(gao)可(ke)靠等(deng)方面。壓(ya)敏電(dian)(dian)阻雖然能(neng)吸收很大的浪涌電(dian)(dian)能(neng)量，但不能(neng)承受毫安級以上的持續電(dian)(dian)流，在用(yong)作過(guo)壓(ya)保護(hu)(hu)時必須(xu)考慮到這一點。
　　四、壓敏電阻的(de)特性參數
　　①壓(ya)(ya)敏(min)電(dian)壓(ya)(ya)UN(U1mA)：通常(chang)以(yi)在(zai)壓(ya)(ya)敏(min)電(dian)阻上通過1mA直(zhi)流電(dian)流時的(de)電(dian)壓(ya)(ya)來表示其是否導(dao)通的(de)標志電(dian)壓(ya)(ya)，這個電(dian)壓(ya)(ya)就稱為壓(ya)(ya)敏(min)電(dian)壓(ya)(ya)UN。壓(ya)(ya)敏(min)電(dian)壓(ya)(ya)也(ye)常(chang)用(yong)符號U1mA表示。壓(ya)(ya)敏(min)電(dian)壓(ya)(ya)的(de)誤差(cha)范圍一般是±10%。在(zai)試驗和實際使用(yong)中，通常(chang)把壓(ya)(ya)敏(min)電(dian)壓(ya)(ya)從正常(chang)值(zhi)下降10%作為壓(ya)(ya)敏(min)電(dian)阻失效的(de)判據。
　　②最(zui)大(da)持續工作電壓(ya)UC：指壓(ya)敏(min)電阻能長期承受的最(zui)大(da)交流電壓(ya)(有效值)Uac或最(zui)大(da)直流電壓(ya)Udc。一(yi)般Uac≈0.64U1mA，Udc≈0.83U1mA。
　　③通流(liu)量(最(zui)大沖(chong)擊(ji)(ji)電(dian)(dian)流(liu))IP：指(zhi)壓敏電(dian)(dian)阻能(neng)夠承(cheng)受(shou)的(de)8/20μs波的(de)最(zui)大沖(chong)擊(ji)(ji)電(dian)(dian)流(liu)峰值(zhi)。“能(neng)夠承(cheng)受(shou)”的(de)含(han)義是，沖(chong)擊(ji)(ji)后壓敏電(dian)(dian)壓的(de)變化率不(bu)大于10%。現行的(de)技術規格書中通常都給(gei)出了沖(chong)擊(ji)(ji)1次的(de)IP值(zhi)。
　　④最(zui)大(da)箝位電(dian)壓(ya)(ya)(限制電(dian)壓(ya)(ya))VC：技術(shu)規格書中給出的(de)最(zui)大(da)箝位電(dian)壓(ya)(ya)值是指給壓(ya)(ya)敏電(dian)阻施(shi)加規定的(de)8/20μs波沖擊電(dian)流IX(A)時壓(ya)(ya)敏電(dian)阻上呈現(xian)的(de)電(dian)壓(ya)(ya)。
　　實(shi)際使用中，壓(ya)敏電壓(ya)越高，施加的(de)沖擊電流越大，限制電壓(ya)(或稱殘壓(ya))就越高，可從產品(pin)給出的(de)V-I曲線上查到。
　　⑤額定能(neng)量E：額定能(neng)量是指壓敏(min)電(dian)(dian)(dian)阻(zu)能(neng)夠承受規定波形的沖擊(ji)電(dian)(dian)(dian)流(liu)沖擊(ji)一次的最(zui)大(da)能(neng)量(沖擊(ji)后(hou)壓敏(min)電(dian)(dian)(dian)壓的變化率不(bu)大(da)于10%)，可用下式(shi)表示：E=K*IP*VC*T
　　式中：IP、VC見上，T為脈(mo)沖寬度，K為與波(bo)形有關的常數。對于8/20μs波(bo)和10/1000μs波(bo)，K=1.4；對于2ms方波(bo)，K=1。
　　⑥額定(ding)功率(最大平均功率)Pm：指壓(ya)敏電阻(zu)在(zai)室溫下，連續承(cheng)(cheng)受多次沖(chong)擊，且各次沖(chong)擊之間間隔時間較短，因(yin)而有(you)熱(re)積累效應的(de)(de)情況下，能(neng)夠承(cheng)(cheng)受的(de)(de)最大平均功率。盡管(guan)壓(ya)敏電阻(zu)能(neng)承(cheng)(cheng)受很大的(de)(de)脈沖(chong)功率，但能(neng)承(cheng)(cheng)受的(de)(de)平均功率卻很小。
　　⑦電(dian)容C0：指壓敏電(dian)阻兩電(dian)極間呈現的電(dian)容，在幾(ji)pF～幾(ji)百nF的范(fan)圍內。體(ti)積越小(xiao)(xiao)，壓敏電(dian)壓越高，電(dian)容越小(xiao)(xiao)。
　　⑧漏(lou)(lou)電流Il：給(gei)(gei)壓(ya)敏電阻施加(jia)最大(da)直流電壓(ya)Udc時流過(guo)的(de)(de)(de)(de)電流。測量漏(lou)(lou)電流時，通常給(gei)(gei)壓(ya)敏電阻加(jia)上Udc=0.83U1mA的(de)(de)(de)(de)電壓(ya)(有(you)時也(ye)用0.75U1mA)。一(yi)般要求靜態(tai)(tai)漏(lou)(lou)電流Il≤20μA(也(ye)有(you)要求≤10μA的(de)(de)(de)(de))。在(zai)實際使(shi)用中，更(geng)關心(xin)的(de)(de)(de)(de)不是靜態(tai)(tai)漏(lou)(lou)電流值(zhi)本身的(de)(de)(de)(de)大(da)小，而是它的(de)(de)(de)(de)穩定(ding)性，即(ji)(ji)在(zai)沖擊(ji)(ji)試驗后或在(zai)高溫(wen)條件下的(de)(de)(de)(de)變(bian)化(hua)率(lv)。在(zai)沖擊(ji)(ji)試驗后或在(zai)高溫(wen)條件下其變(bian)化(hua)率(lv)不超(chao)過(guo)一(yi)倍(bei)，即(ji)(ji)認(ren)為(wei)是穩定(ding)的(de)(de)(de)(de)。
　　⑨非線性指數α：指電壓的(de)變化對電流的(de)影響能力，可用公式表示(shi)為：
　　I=KUα或α=loglog
　　由(you)前(qian)式可見，α越大表明電壓的變化對電流的影響能力越大，非線性(xing)特(te)(te)性(xing)越好(hao)。由(you)后式可見，α是(shi)伏安特(te)(te)性(xing)上各(ge)點斜率的倒數，特(te)(te)性(xing)越平坦的地方，α越大(漏(lou)電流區和飽和區α=1，又稱低α區)。用儀(yi)器測量時，一般設(she)定I2=1mA，I1=0.1mA，所(suo)以
　　αT=1/log(U1mA/U0.1mA)
　　五、壓(ya)敏電阻(zu)的降額特性
　　對(dui)壓敏電阻(zu)進行沖擊試驗時，隨著所要(yao)進行的沖擊次(ci)數(shu)的增(zeng)加，每次(ci)所施(shi)加的沖擊電流要(yao)相應地減小(xiao)。例如(ru)：Ф20基片的標(biao)準壓敏電阻(zu)(U1mA≥82V的)，其降額特性如(ru)下表所示(可從廠家給出的浪涌壽(shou)命(ming)次(ci)數(shu)定(ding)額曲(qu)線中查到)：
　　允許沖擊次(ci)數1次(ci)2次(ci)10次(ci)100次(ci)1000次(ci)10000次(ci)
　　每次沖擊電流6500A4000A2000A1000A430A200A
　　六、壓(ya)敏電阻(zu)的測量
　　測量時(shi)將萬用(yong)表(biao)置10k檔，表(biao)筆接(jie)于電阻(zu)兩(liang)端，萬用(yong)表(biao)上(shang)應顯示出壓敏電阻(zu)上(shang)標示的阻(zu)值，如果(guo)超出這個(ge)數值很大，則說(shuo)明壓敏電阻(zu)已損
　　七、壓(ya)敏電阻的(de)選型
　　壓(ya)(ya)敏(min)電阻的選(xuan)用，一般(ban)選(xuan)擇標稱壓(ya)(ya)敏(min)電壓(ya)(ya)V1mA和通(tong)流容量兩個參數。
　　1、所謂壓(ya)(ya)(ya)(ya)(ya)敏電(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)，即擊穿電(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)或閾(yu)值(zhi)(zhi)(zhi)電(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)。指在規(gui)定電(dian)(dian)流(liu)下(xia)的(de)電(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)值(zhi)(zhi)(zhi)，大(da)多數情況下(xia)用(yong)(yong)1mA直(zhi)流(liu)電(dian)(dian)流(liu)通入壓(ya)(ya)(ya)(ya)(ya)敏電(dian)(dian)阻器時測得的(de)電(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)值(zhi)(zhi)(zhi)，其產品的(de)壓(ya)(ya)(ya)(ya)(ya)敏電(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)范圍可(ke)以從10-9000V不等(deng)。可(ke)根據(ju)具(ju)體(ti)需要(yao)正確選用(yong)(yong)。一(yi)般1mA=“1”.5Vp=“2”.2VAC，式中，Vp為電(dian)(dian)路額(e)(e)定電(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)的(de)峰(feng)值(zhi)(zhi)(zhi)。VAC為額(e)(e)定交流(liu)電(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)的(de)有效值(zhi)(zhi)(zhi)。ZnO壓(ya)(ya)(ya)(ya)(ya)敏電(dian)(dian)阻的(de)電(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)值(zhi)(zhi)(zhi)選擇(ze)是(shi)至關重要(yao)的(de)，它關系到保護效果(guo)與使用(yong)(yong)壽命。如(ru)一(yi)臺用(yong)(yong)電(dian)(dian)器的(de)額(e)(e)定電(dian)(dian)源電(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)為220V，則壓(ya)(ya)(ya)(ya)(ya)敏電(dian)(dian)阻電(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)值(zhi)(zhi)(zhi)V1mA=“1”.5Vp=“1”.5××220V=“476V”，V1mA=“2”.2VAC=“2”.2×220V=“484V”，因此(ci)壓(ya)(ya)(ya)(ya)(ya)敏電(dian)(dian)阻的(de)擊穿電(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)可(ke)選在470-480V之間。
　　2、所(suo)謂(wei)通(tong)流(liu)(liu)(liu)(liu)容量(liang)(liang)，即最(zui)大(da)脈(mo)沖(chong)電流(liu)(liu)(liu)(liu)的(de)峰值(zhi)(zhi)是環境溫度(du)為25℃情況下，對于(yu)規定(ding)的(de)沖(chong)擊電流(liu)(liu)(liu)(liu)波形和規定(ding)的(de)沖(chong)擊電流(liu)(liu)(liu)(liu)次數而言，壓(ya)(ya)敏(min)(min)電壓(ya)(ya)的(de)變(bian)化不(bu)超過±10%時(shi)的(de)最(zui)大(da)脈(mo)沖(chong)電流(liu)(liu)(liu)(liu)值(zhi)(zhi)。為了延(yan)長(chang)器件的(de)使(shi)用(yong)壽命(ming)，ZnO壓(ya)(ya)敏(min)(min)電阻(zu)(zu)所(suo)吸收的(de)浪涌電流(liu)(liu)(liu)(liu)幅值(zhi)(zhi)應小于(yu)手(shou)冊中給出(chu)的(de)產(chan)品最(zui)大(da)通(tong)流(liu)(liu)(liu)(liu)量(liang)(liang)。然而從保護(hu)效果(guo)出(chu)發，要(yao)求(qiu)所(suo)選用(yong)的(de)通(tong)流(liu)(liu)(liu)(liu)量(liang)(liang)大(da)一些好。在許多情況下，實際發生的(de)通(tong)流(liu)(liu)(liu)(liu)量(liang)(liang)是很難精(jing)確(que)計算的(de)，則選用(yong)2-20KA的(de)產(chan)品。如手(shou)頭(tou)產(chan)品的(de)通(tong)流(liu)(liu)(liu)(liu)量(liang)(liang)不(bu)能滿足使(shi)用(yong)要(yao)求(qiu)時(shi)，可(ke)將幾只單個的(de)壓(ya)(ya)敏(min)(min)電阻(zu)(zu)并聯使(shi)用(yong)，并聯后的(de)壓(ya)(ya)敏(min)(min)電不(bu)變(bian)，其通(tong)流(liu)(liu)(liu)(liu)量(liang)(liang)為各單只壓(ya)(ya)敏(min)(min)電阻(zu)(zu)數值(zhi)(zhi)之(zhi)和。要(yao)求(qiu)并聯的(de)壓(ya)(ya)敏(min)(min)電阻(zu)(zu)伏(fu)安(an)特性盡量(liang)(liang)相同，否則易(yi)引(yin)起分流(liu)(liu)(liu)(liu)不(bu)均勻而損壞(huai)壓(ya)(ya)敏(min)(min)電阻(zu)(zu)。
　　八(ba)、壓敏(min)電阻(zu)的使用
　　壓(ya)敏電阻(zu)一般并聯在電路(lu)中使用，當電阻(zu)兩(liang)端(duan)的電壓(ya)發生急劇變化時(shi)，電阻(zu)短路(lu)將電流(liu)保險絲熔斷(duan)，起到保護(hu)(hu)作(zuo)用。壓(ya)敏電阻(zu)在電路(lu)中，常用于電源(yuan)過壓(ya)保護(hu)(hu)和穩(wen)壓(ya)。
　　電源(yuan)防雷器的(de)(de)可靠性、安全(quan)性在(zai)很大程度上(shang)依賴于(yu)壓(ya)(ya)敏(min)電阻的(de)(de)正確使用，以下(xia)原則可供使用參考(kao)。特別(bie)(bie)(bie)要指出的(de)(de)是，在(zai)電源(yuan)防雷設計(ji)中還(huan)要考(kao)慮各個地方的(de)(de)電源(yuan)質量差(cha)別(bie)(bie)(bie)、雷擊頻度和(he)強度的(de)(de)差(cha)別(bie)(bie)(bie)、被保(bao)護(hu)(hu)設備(bei)的(de)(de)安裝使用情況和(he)沖擊耐受能(neng)力等的(de)(de)差(cha)別(bie)(bie)(bie)，不能(neng)用一個公式(shi)照搬照套。設計(ji)好的(de)(de)防雷保(bao)護(hu)(hu)裝置必須在(zai)現場使用條件下(xia)或盡(jin)可能(neng)接近真實情況的(de)(de)模擬條件下(xia)進行(xing)試驗驗證。①壓(ya)(ya)敏(min)電壓(ya)(ya)的(de)(de)計(ji)算：
　　一般可用(yong)下(xia)式計(ji)算：
　　U1mA=KUac
　　式中：K為(wei)(wei)與電(dian)(dian)源質量有關的系數，一般取(qu)K=(2～3)，電(dian)(dian)源質量較(jiao)(jiao)好的城市可(ke)取(qu)小些(xie)，電(dian)(dian)源質量較(jiao)(jiao)差的農村(特別是(shi)山區)可(ke)取(qu)大些(xie)。Uac為(wei)(wei)交流電(dian)(dian)源電(dian)(dian)壓(ya)有效(xiao)值。對于220V～240V交流電(dian)(dian)源防雷(lei)器，應(ying)選(xuan)用壓(ya)敏電(dian)(dian)壓(ya)為(wei)(wei)470V～620V的壓(ya)敏電(dian)(dian)阻較(jiao)(jiao)合適。選(xuan)用壓(ya)敏電(dian)(dian)壓(ya)高一點的壓(ya)敏電(dian)(dian)阻，可(ke)以(yi)降低故障率，延長使用壽命，但殘壓(ya)略有增大。
　　②標(biao)稱放(fang)電電流的計(ji)算(suan)：
　　壓(ya)敏電(dian)(dian)(dian)阻的(de)標稱放電(dian)(dian)(dian)電(dian)(dian)(dian)流應大于要求承受的(de)浪涌電(dian)(dian)(dian)流或每年可能(neng)出現(xian)的(de)最(zui)大浪涌電(dian)(dian)(dian)流。標稱放電(dian)(dian)(dian)電(dian)(dian)(dian)流應按壓(ya)敏電(dian)(dian)(dian)阻浪涌壽命(ming)次數定額曲線中(zhong)沖擊(ji)(ji)10次以(yi)上的(de)數值進(jin)行計(ji)算(suan)，約為(wei)最(zui)大沖擊(ji)(ji)通流量(liang)的(de)30%(即0.3IP)左右。
　　③壓敏電阻的并聯(lian)：
　　當一個(ge)(ge)壓(ya)敏(min)電(dian)(dian)阻滿(man)足不了(le)標稱(cheng)(cheng)放電(dian)(dian)電(dian)(dian)流(liu)的(de)要(yao)(yao)求時，應采用(yong)多個(ge)(ge)壓(ya)敏(min)電(dian)(dian)阻并聯使(shi)用(yong)。有時為了(le)降(jiang)低限制(zhi)電(dian)(dian)壓(ya)，即使(shi)標稱(cheng)(cheng)放電(dian)(dian)電(dian)(dian)流(liu)滿(man)足要(yao)(yao)求也(ye)采用(yong)多個(ge)(ge)壓(ya)敏(min)電(dian)(dian)阻并聯。要(yao)(yao)特別注意的(de)是(shi)，壓(ya)敏(min)電(dian)(dian)阻并聯使(shi)用(yong)時，一定要(yao)(yao)嚴格挑選參數一致的(de)(例如：ΔU1mA≤3V，Δα≤3)進行配對(dui)，以保證電(dian)(dian)流(liu)的(de)均勻分配。
　　九、壓敏電阻使用(yong)時的(de)注意(yi)事項
　　壓(ya)(ya)(ya)敏電(dian)(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)(zu)(zu)的(de)失(shi)(shi)(shi)(shi)效(xiao)模式通常是短路(lu)(lu)(lu)，為(wei)了防止壓(ya)(ya)(ya)敏電(dian)(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)(zu)(zu)的(de)失(shi)(shi)(shi)(shi)效(xiao)造(zao)成(cheng)電(dian)(dian)(dian)(dian)(dian)源短路(lu)(lu)(lu)而(er)起(qi)(qi)火(huo)(huo)，可(ke)以(yi)在(zai)(zai)每個(ge)壓(ya)(ya)(ya)敏電(dian)(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)(zu)(zu)上串(chuan)聯一個(ge)溫(wen)度保(bao)(bao)(bao)(bao)險(xian)管(guan)或熱脫離(li)機(ji)構。溫(wen)度保(bao)(bao)(bao)(bao)險(xian)管(guan)應與(yu)壓(ya)(ya)(ya)敏電(dian)(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)(zu)(zu)有(you)良好的(de)熱耦合，當壓(ya)(ya)(ya)敏電(dian)(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)(zu)(zu)失(shi)(shi)(shi)(shi)效(xiao)(高(gao)阻(zu)(zu)(zu)(zu)(zu)抗短路(lu)(lu)(lu))時(shi)，它所產生的(de)熱量把(ba)溫(wen)度保(bao)(bao)(bao)(bao)險(xian)管(guan)熔斷，從而(er)使(shi)(shi)(shi)失(shi)(shi)(shi)(shi)效(xiao)的(de)壓(ya)(ya)(ya)敏電(dian)(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)(zu)(zu)與(yu)電(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu)分離(li)，確保(bao)(bao)(bao)(bao)設備的(de)安全。當較高(gao)的(de)工(gong)(gong)(gong)(gong)頻(pin)暫時(shi)過(guo)電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)作用(yong)(yong)在(zai)(zai)壓(ya)(ya)(ya)敏電(dian)(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)(zu)(zu)上時(shi)，可(ke)能(neng)使(shi)(shi)(shi)壓(ya)(ya)(ya)敏電(dian)(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)(zu)(zu)瞬間擊(ji)穿短路(lu)(lu)(lu)(低(di)阻(zu)(zu)(zu)(zu)(zu)抗短路(lu)(lu)(lu))，而(er)溫(wen)度保(bao)(bao)(bao)(bao)險(xian)管(guan)還來不及熔斷，還可(ke)能(neng)起(qi)(qi)火(huo)(huo)。為(wei)避免這(zhe)種(zhong)現象發生，可(ke)在(zai)(zai)每個(ge)壓(ya)(ya)(ya)敏電(dian)(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)(zu)(zu)上再(zai)串(chuan)聯一個(ge)耐(nai)沖擊(ji)工(gong)(gong)(gong)(gong)頻(pin)保(bao)(bao)(bao)(bao)險(xian)絲(si)(單(dan)用(yong)(yong)工(gong)(gong)(gong)(gong)頻(pin)保(bao)(bao)(bao)(bao)險(xian)絲(si)則在(zai)(zai)老化(hua)失(shi)(shi)(shi)(shi)效(xiao)時(shi)可(ke)能(neng)不熔斷)。也可(ke)以(yi)把(ba)壓(ya)(ya)(ya)敏電(dian)(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)(zu)(zu)與(yu)陶瓷(ci)(ci)氣(qi)體(ti)(ti)放電(dian)(dian)(dian)(dian)(dian)管(guan)串(chuan)聯使(shi)(shi)(shi)用(yong)(yong)，正(zheng)常工(gong)(gong)(gong)(gong)作時(shi)陶瓷(ci)(ci)氣(qi)體(ti)(ti)放電(dian)(dian)(dian)(dian)(dian)管(guan)不導通，壓(ya)(ya)(ya)敏電(dian)(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)(zu)(zu)沒(mei)有(you)漏電(dian)(dian)(dian)(dian)(dian)流，可(ke)以(yi)大(da)大(da)延長(chang)使(shi)(shi)(shi)用(yong)(yong)壽命；受浪涌沖擊(ji)時(shi)，陶瓷(ci)(ci)氣(qi)體(ti)(ti)放電(dian)(dian)(dian)(dian)(dian)管(guan)首先(xian)擊(ji)穿，然(ran)后由壓(ya)(ya)(ya)敏電(dian)(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)(zu)(zu)限制浪涌電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)，總(zong)的(de)殘(can)壓(ya)(ya)(ya)為(wei)兩者(zhe)之和(he)，略有(you)增大(da)(幾(ji)十伏)；沖擊(ji)過(guo)去后，由于壓(ya)(ya)(ya)敏電(dian)(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)(zu)(zu)限制了電(dian)(dian)(dian)(dian)(dian)流，放電(dian)(dian)(dian)(dian)(dian)管(guan)不能(neng)維持導通而(er)熄弧(hu)，恢復為(wei)正(zheng)常工(gong)(gong)(gong)(gong)作狀(zhuang)態；當壓(ya)(ya)(ya)敏電(dian)(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)(zu)(zu)短路(lu)(lu)(lu)失(shi)(shi)(shi)(shi)效(xiao)后，因(yin)(yin)陶瓷(ci)(ci)氣(qi)體(ti)(ti)放電(dian)(dian)(dian)(dian)(dian)管(guan)流過(guo)很大(da)的(de)工(gong)(gong)(gong)(gong)頻(pin)電(dian)(dian)(dian)(dian)(dian)流也會(hui)很快失(shi)(shi)(shi)(shi)效(xiao)，但它的(de)失(shi)(shi)(shi)(shi)效(xiao)模式絕(jue)大(da)多數是開(kai)路(lu)(lu)(lu)，因(yin)(yin)而(er)不易引起(qi)(qi)火(huo)(huo)災。
　　所以，我們設備(bei)中壓(ya)(ya)敏(min)電(dian)(dian)(dian)阻(zu)的(de)選型基本沒(mei)有錯誤，根據公式，應(ying)(ying)(ying)(ying)該(gai)(gai)選取(qu)壓(ya)(ya)敏(min)電(dian)(dian)(dian)壓(ya)(ya)即標稱電(dian)(dian)(dian)壓(ya)(ya)為130V的(de)壓(ya)(ya)敏(min)電(dian)(dian)(dian)阻(zu)，根據就上(shang)不就下的(de)原則，實際應(ying)(ying)(ying)(ying)該(gai)(gai)選取(qu)14D151型號。而且，在實際使(shi)用方法上(shang)，我們不應(ying)(ying)(ying)(ying)該(gai)(gai)直接將壓(ya)(ya)敏(min)電(dian)(dian)(dian)阻(zu)并接，根據實際情(qing)況，應(ying)(ying)(ying)(ying)該(gai)(gai)把壓(ya)(ya)敏(min)電(dian)(dian)(dian)阻(zu)與(yu)陶(tao)瓷氣體(ti)放電(dian)(dian)(dian)管串聯使(shi)用。

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