一、電阻的種類有哪些

1、按伏安特性分類

可分(fen)為線性(xing)電(dian)阻(zu)和非線性(xing)電(dian)阻(zu)。對大多數導體來說，在(zai)一定的(de)溫度下，其電(dian)阻(zu)幾乎維持不變而為一定值，這類電(dian)阻(zu)稱為線性(xing)電(dian)阻(zu)。

有些材料的(de)(de)電(dian)(dian)(dian)阻明顯地隨著電(dian)(dian)(dian)流(liu)（或電(dian)(dian)(dian)壓）而變化，其伏(fu)安(an)特性(xing)是一條曲線(xian)(xian)，這(zhe)類電(dian)(dian)(dian)阻稱(cheng)為非線(xian)(xian)性(xing)電(dian)(dian)(dian)阻。非線(xian)(xian)性(xing)電(dian)(dian)(dian)阻在(zai)某一給定的(de)(de)電(dian)(dian)(dian)壓（或電(dian)(dian)(dian)流(liu)）作用(yong)下，電(dian)(dian)(dian)壓與(yu)電(dian)(dian)(dian)流(liu)的(de)(de)比(bi)值(zhi)為在(zai)該工作點(dian)下的(de)(de)靜態電(dian)(dian)(dian)阻，伏(fu)安(an)特性(xing)曲線(xian)(xian)上(shang)的(de)(de)斜率為動態電(dian)(dian)(dian)阻。表達(da)非線(xian)(xian)性(xing)電(dian)(dian)(dian)阻特性(xing)的(de)(de)方式比(bi)較復雜，但這(zhe)些非線(xian)(xian)性(xing)關系在(zai)電(dian)(dian)(dian)子電(dian)(dian)(dian)路中得到了廣泛的(de)(de)應用(yong)。

2、按材料分類

a.線(xian)繞(rao)電(dian)阻(zu)(zu)器(qi)由電(dian)阻(zu)(zu)線(xian)繞(rao)成電(dian)阻(zu)(zu)器(qi)，用高(gao)(gao)阻(zu)(zu)合金線(xian)繞(rao)在絕緣(yuan)(yuan)骨架(jia)上制成，外面涂有(you)耐(nai)熱的(de)(de)釉絕緣(yuan)(yuan)層或絕緣(yuan)(yuan)漆。繞(rao)線(xian)電(dian)阻(zu)(zu)具有(you)較低的(de)(de)溫度(du)系數(shu)(shu)，阻(zu)(zu)值精度(du)高(gao)(gao)，穩定性好，耐(nai)熱耐(nai)腐蝕，主要做精密大功(gong)率電(dian)阻(zu)(zu)使用，缺(que)點是高(gao)(gao)頻性能(neng)差，時間常數(shu)(shu)大。

b.碳合成電阻器由碳及合成塑膠壓制(zhi)成而成。

c.碳(tan)(tan)膜(mo)電(dian)阻(zu)(zu)器(qi)在(zai)瓷(ci)管上鍍上一層碳(tan)(tan)而(er)成，將(jiang)結晶碳(tan)(tan)沉積(ji)在(zai)陶瓷(ci)棒骨架上制成。碳(tan)(tan)膜(mo)電(dian)阻(zu)(zu)器(qi)成本低、性能穩定、阻(zu)(zu)值范圍寬、溫度(du)系數和電(dian)壓(ya)系數低，是目前應用最廣泛的電(dian)阻(zu)(zu)器(qi)。

d.金屬膜電(dian)阻(zu)(zu)器(qi)在瓷管上(shang)鍍(du)上(shang)一層金屬而成，用真空蒸發的(de)方(fang)法將(jiang)合金材料蒸鍍(du)于陶瓷棒(bang)骨(gu)架表面(mian)。金屬膜電(dian)阻(zu)(zu)比(bi)碳膜電(dian)阻(zu)(zu)的(de)精度高，穩(wen)定性好，噪聲，溫(wen)度系數小。在儀器(qi)儀表及通訊設備中大量采(cai)用。

e.金屬氧(yang)化(hua)膜(mo)電阻器在(zai)瓷(ci)管上鍍上一(yi)層(ceng)氧(yang)化(hua)錫(xi)而成，在(zai)絕緣棒上沉積一(yi)層(ceng)金屬氧(yang)化(hua)物。由于其本身即是氧(yang)化(hua)物，所以高溫下穩定，耐熱沖擊，負載能力強。按用途(tu)分，有通(tong)用、精(jing)密、高頻、高壓、高阻、大功率和電阻網絡等。

3、特殊電阻器

a.保(bao)險電(dian)(dian)阻(zu)：又叫熔斷(duan)電(dian)(dian)阻(zu)器(qi)，在(zai)正常情況下起著電(dian)(dian)阻(zu)和(he)保(bao)險絲的(de)雙(shuang)重作用(yong)，當電(dian)(dian)路(lu)出現故障(zhang)而使(shi)其功(gong)率超過額定功(gong)率時，它會像保(bao)險絲一(yi)樣熔斷(duan)使(shi)連接(jie)電(dian)(dian)路(lu)斷(duan)開。保(bao)險絲電(dian)(dian)阻(zu)一(yi)般電(dian)(dian)阻(zu)值(zhi)都小（0.33Ω～10KΩ），功(gong)率也較小。保(bao)險絲電(dian)(dian)阻(zu)器(qi)常用(yong)型(xing)號(hao)有：RF10型(xing)、RF111-5保(bao)險絲電(dian)(dian)阻(zu)器(qi)的(de)符(fu)號(hao)型(xing)、RRD0910型(xing)、RRD0911型(xing)等(deng)。

b.敏(min)(min)(min)感(gan)電(dian)(dian)(dian)(dian)阻器(qi)(qi)：是(shi)指(zhi)其電(dian)(dian)(dian)(dian)阻值(zhi)對于(yu)某種物理量(liang)(liang)（如(ru)溫(wen)度、濕(shi)度、光照、電(dian)(dian)(dian)(dian)壓(ya)、機械力、以(yi)及氣體(ti)(ti)濃度等(deng)）具有敏(min)(min)(min)感(gan)特性，當(dang)這些(xie)物理量(liang)(liang)發生(sheng)變(bian)化時，敏(min)(min)(min)感(gan)電(dian)(dian)(dian)(dian)阻的(de)阻值(zhi)就會(hui)隨物理量(liang)(liang)變(bian)化而(er)發生(sheng)改變(bian)，呈現不(bu)同(tong)的(de)電(dian)(dian)(dian)(dian)阻值(zhi)。根據對不(bu)同(tong)物理量(liang)(liang)敏(min)(min)(min)感(gan)，敏(min)(min)(min)感(gan)電(dian)(dian)(dian)(dian)阻器(qi)(qi)可分為熱(re)敏(min)(min)(min)、濕(shi)敏(min)(min)(min)、光敏(min)(min)(min)、壓(ya)敏(min)(min)(min)、力敏(min)(min)(min)、磁敏(min)(min)(min)和氣敏(min)(min)(min)等(deng)類型(xing)敏(min)(min)(min)感(gan)電(dian)(dian)(dian)(dian)阻。敏(min)(min)(min)感(gan)電(dian)(dian)(dian)(dian)阻器(qi)(qi)所用的(de)材(cai)料幾乎都(dou)是(shi)半(ban)導(dao)體(ti)(ti)材(cai)料，這類電(dian)(dian)(dian)(dian)阻器(qi)(qi)也稱(cheng)為半(ban)導(dao)體(ti)(ti)電(dian)(dian)(dian)(dian)阻器(qi)(qi)。

c.熱(re)(re)敏(min)(min)電阻(zu)的阻(zu)值(zhi)(zhi)隨溫(wen)(wen)度(du)(du)變化而(er)變化，溫(wen)(wen)度(du)(du)升高(gao)阻(zu)為負溫(wen)(wen)度(du)(du)系(xi)數(shu)(shu)（NTC）熱(re)(re)敏(min)(min)電阻(zu)。應用較多的是負溫(wen)(wen)度(du)(du)系(xi)數(shu)(shu)熱(re)(re)敏(min)(min)電阻(zu)，又可分為普通型負溫(wen)(wen)度(du)(du)系(xi)數(shu)(shu)熱(re)(re)敏(min)(min)電阻(zu)；穩壓型負溫(wen)(wen)度(du)(du)系(xi)數(shu)(shu)熱(re)(re)敏(min)(min)電阻(zu)；測溫(wen)(wen)型負溫(wen)(wen)度(du)(du)系(xi)數(shu)(shu)熱(re)(re)敏(min)(min)電阻(zu)等。光(guang)敏(min)(min)電阻(zu)是電阻(zu)的阻(zu)值(zhi)(zhi)隨入射(she)光(guang)的強弱(ruo)變化而(er)改(gai)變，當入射(she)光(guang)增強時，光(guang)敏(min)(min)電阻(zu)的減(jian)小，入射(she)光(guang)減(jian)弱(ruo)時電阻(zu)值(zhi)(zhi)增大。

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二、電阻器選用的方法

1、固定電阻器的選用

固定電(dian)(dian)(dian)阻(zu)(zu)(zu)(zu)器(qi)(qi)(qi)有多種(zhong)類型，選(xuan)擇哪一種(zhong)材料和(he)(he)(he)結構的(de)電(dian)(dian)(dian)阻(zu)(zu)(zu)(zu)器(qi)(qi)(qi)，應根據應用(yong)電(dian)(dian)(dian)路(lu)的(de)具體(ti)要求而定。高頻電(dian)(dian)(dian)路(lu)應選(xuan)用(yong)分(fen)布電(dian)(dian)(dian)感和(he)(he)(he)分(fen)布電(dian)(dian)(dian)容小(xiao)的(de)非(fei)線繞電(dian)(dian)(dian)阻(zu)(zu)(zu)(zu)器(qi)(qi)(qi)，例如碳(tan)膜(mo)(mo)電(dian)(dian)(dian)阻(zu)(zu)(zu)(zu)器(qi)(qi)(qi)、金屬(shu)電(dian)(dian)(dian)阻(zu)(zu)(zu)(zu)器(qi)(qi)(qi)和(he)(he)(he)金屬(shu)氧化膜(mo)(mo)電(dian)(dian)(dian)阻(zu)(zu)(zu)(zu)器(qi)(qi)(qi)，薄膜(mo)(mo)電(dian)(dian)(dian)阻(zu)(zu)(zu)(zu)器(qi)(qi)(qi)，厚膜(mo)(mo)電(dian)(dian)(dian)阻(zu)(zu)(zu)(zu)器(qi)(qi)(qi)，合(he)金電(dian)(dian)(dian)阻(zu)(zu)(zu)(zu)器(qi)(qi)(qi)，防腐(fu)蝕鍍膜(mo)(mo)電(dian)(dian)(dian)阻(zu)(zu)(zu)(zu)器(qi)(qi)(qi)等。高增益小(xiao)信號(hao)放大(da)電(dian)(dian)(dian)路(lu)應選(xuan)用(yong)低噪(zao)(zao)聲電(dian)(dian)(dian)阻(zu)(zu)(zu)(zu)器(qi)(qi)(qi)，例如金屬(shu)膜(mo)(mo)電(dian)(dian)(dian)阻(zu)(zu)(zu)(zu)器(qi)(qi)(qi)、碳(tan)膜(mo)(mo)電(dian)(dian)(dian)阻(zu)(zu)(zu)(zu)器(qi)(qi)(qi)和(he)(he)(he)線繞電(dian)(dian)(dian)阻(zu)(zu)(zu)(zu)器(qi)(qi)(qi)，而不能(neng)使用(yong)噪(zao)(zao)聲較大(da)的(de)合(he)成(cheng)碳(tan)膜(mo)(mo)電(dian)(dian)(dian)阻(zu)(zu)(zu)(zu)器(qi)(qi)(qi)和(he)(he)(he)有機實心電(dian)(dian)(dian)阻(zu)(zu)(zu)(zu)器(qi)(qi)(qi)。

所選(xuan)電(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)器(qi)(qi)(qi)(qi)的(de)電(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)值(zhi)應接(jie)近應用電(dian)(dian)(dian)(dian)路中(zhong)計算值(zhi)的(de)一個標稱(cheng)值(zhi)，應優(you)先選(xuan)用標準系列的(de)電(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)器(qi)(qi)(qi)(qi)。一般電(dian)(dian)(dian)(dian)路使(shi)用的(de)電(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)器(qi)(qi)(qi)(qi)允許誤差為(wei)±5%~±10%。精密(mi)儀器(qi)(qi)(qi)(qi)及特(te)殊電(dian)(dian)(dian)(dian)路中(zhong)使(shi)用的(de)電(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)器(qi)(qi)(qi)(qi)，應選(xuan)用精密(mi)電(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)器(qi)(qi)(qi)(qi)，對精密(mi)度為(wei)1%以內的(de)電(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)，如0.01%，0.1%，0.5%這些量(liang)級(ji)的(de)電(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)應采用捷比(bi)信電(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)。所選(xuan)電(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)器(qi)(qi)(qi)(qi)的(de)額定功率，要(yao)(yao)符合(he)應用電(dian)(dian)(dian)(dian)路中(zhong)對電(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)器(qi)(qi)(qi)(qi)功率容量(liang)的(de)要(yao)(yao)求，一般不(bu)應隨意加大或減小電(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)器(qi)(qi)(qi)(qi)的(de)功率。

若(ruo)電(dian)路要求是功(gong)率(lv)型電(dian)阻器，則其(qi)額(e)定功(gong)率(lv)可(ke)高(gao)于實際應用電(dian)路要求功(gong)率(lv)的(de)1~2倍。

2、熔斷電阻器的選用

熔斷(duan)電(dian)阻(zu)器具(ju)有保(bao)護功能(neng)的電(dian)阻(zu)器。選用(yong)時(shi)應考慮其雙重性(xing)能(neng)，根據電(dian)路(lu)的具(ju)體(ti)要求選擇其阻(zu)值和功率等(deng)參數。既(ji)要保(bao)證(zheng)它在(zai)(zai)過負荷時(shi)能(neng)快速(su)熔斷(duan)，又要保(bao)證(zheng)它在(zai)(zai)正常(chang)條件下能(neng)長期穩定的工作。電(dian)阻(zu)值過大或(huo)功率過大，均不能(neng)起到保(bao)護作用(yong)。

三、電阻器選用的基本原則

1、選擇通過認(ren)證機構認(ren)證的(de)生產線制造出的(de)執行高水平標準的(de)電阻器。

2、選擇(ze)具備功能優勢(shi)、質量優勢(shi)、效率優勢(shi)、功能價格比優勢(shi)、服務(wu)優勢(shi)的制造商生產(chan)的電阻器。

3、選擇能滿足上述要求的上型號目錄的制造商，并向其直接訂購電阻器。