熱敏電阻器是敏感元件的一類，按照溫度系數不同分為正溫度系數熱敏電阻器(PTC)和負溫度系數熱敏電阻器(NTC)。熱敏電阻器的典型特點是對溫度敏感，不同的溫度下表現出不同的電阻值。正溫度系數熱敏電阻器(PTC)在溫度越高時電阻值越大，負溫度系數熱敏電阻器(NTC)在溫度越高時電阻值越低，它們同屬于半導體器件。熱敏電阻型號

但需要注(zhu)意(yi)的是:熱敏電阻在進出口環(huan)節不屬(shu)于稅目85.41項(xiang)下的半導(dao)體器件。

熱敏電阻的主要特點是:

①靈(ling)敏度較(jiao)高(gao)，其電(dian)阻溫(wen)度系數要(yao)比(bi)金屬大10~100倍以上，能檢測出10-6℃的溫(wen)度變化;

②工作溫度(du)范(fan)圍寬(kuan)，常溫器(qi)件適(shi)用(yong)于(yu)-55℃~315℃，高(gao)溫器(qi)件適(shi)用(yong)溫度(du)高(gao)于(yu)315℃(目前可達到2000℃)，低溫器(qi)件適(shi)用(yong)于(yu)-273℃~-55℃;

③體(ti)積小，能夠測(ce)量(liang)其他溫度計無法(fa)測(ce)量(liang)的空(kong)隙、腔體(ti)及生(sheng)物體(ti)內血管(guan)的溫度;

④使用方便，電阻值可在0.1~100kΩ間任(ren)意選擇;

⑤易加工成復(fu)雜的形狀，可大批量生產;

⑥穩定(ding)性(xing)好、過載能力強。

工作原理：熱敏電阻將長期處于不動作狀態;當環境溫度和電流處于c區時，熱敏電阻的散熱功率與發熱功率接近，因而可能動作也可能不動作。熱敏電阻在環境溫度相同時，動作時間隨著電流的增加而急劇縮短;熱敏電阻在環境溫度相對較高時具有更短的動作時間和較小的維持電流及動作電流。熱敏電阻型號

1、ptc效應是(shi)一種材(cai)料(liao)(liao)具(ju)有(you)ptc(positivetemperaturecoefficient)效應，即正溫度(du)(du)系數效應，僅指此材(cai)料(liao)(liao)的(de)電(dian)阻會隨溫度(du)(du)的(de)升高而增(zeng)加。如(ru)大多數金屬材(cai)料(liao)(liao)都具(ju)有(you)ptc效應。在這些材(cai)料(liao)(liao)中，ptc效應表現(xian)為電(dian)阻隨溫度(du)(du)增(zeng)加而線(xian)性增(zeng)加，這就是(shi)通常所說的(de)線(xian)性ptc效應。

2、非線性ptc效應(ying)經過(guo)相變的(de)材料會呈現出電(dian)(dian)阻沿(yan)狹窄溫度范圍(wei)內急劇(ju)增加幾(ji)個至十幾(ji)個數(shu)量(liang)級的(de)現象(xiang)，即非線性ptc效應(ying)，相當多種類型的(de)導電(dian)(dian)聚合(he)體(ti)會呈現出這種效應(ying)，如(ru)高分子ptc熱敏電(dian)(dian)阻。這些導電(dian)(dian)聚合(he)體(ti)對于制造過(guo)電(dian)(dian)流保護裝置(zhi)來(lai)說非常有用。

3、高分子ptc熱(re)敏電(dian)阻(zu)用(yong)于過流保(bao)(bao)(bao)(bao)護高分子ptc熱(re)敏電(dian)阻(zu)又(you)經常被人(ren)們(men)稱為(wei)自(zi)恢(hui)復保(bao)(bao)(bao)(bao)險絲(si)(下面簡稱為(wei)熱(re)敏電(dian)阻(zu))，由于具有*的(de)正溫(wen)度系數電(dian)阻(zu)特(te)性，因而極為(wei)適合用(yong)作過流保(bao)(bao)(bao)(bao)護器件。熱(re)敏電(dian)阻(zu)的(de)使用(yong)方(fang)法象(xiang)普(pu)通(tong)保(bao)(bao)(bao)(bao)險絲(si)一樣，是串(chuan)聯在(zai)電(dian)路中使用(yong)。

當電路正常工作時，熱敏電阻溫度與室溫相近、電阻很小，串聯在電路中不會阻礙電流通過;而當電路因故障而出現過電流時，熱敏電阻由于發熱功率增加導致溫度上升，當溫度超過開關溫度(時，電阻瞬間會劇增，回路中的電流迅速減小到安全值.為熱敏電阻對交流電路保護過程中電流的變化示意圖。熱敏電阻動作后，電路中電流有了大幅度的降低，圖中t為熱敏電阻的動作時間。由于高分子ptc熱敏電阻的可設計性好，可通過改變自身的開關溫度(ts)來調節其對溫度的敏感程度，因而可同時起到過溫保護和過流保護兩種作用，如kt16-1700dl規格熱敏電阻由于動作溫度很低，因而適用于鋰離子電池和鎳氫電池的過流及過溫保護。熱敏電阻型號

環(huan)(huan)(huan)境溫度對(dui)(dui)高(gao)分子ptc熱(re)(re)(re)(re)(re)敏(min)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)(zu)的(de)影響(xiang)高(gao)分子ptc熱(re)(re)(re)(re)(re)敏(min)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)(zu)是一種直(zhi)熱(re)(re)(re)(re)(re)式、階躍型熱(re)(re)(re)(re)(re)敏(min)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)(zu)，其(qi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)(zu)變化過程與自身的(de)發熱(re)(re)(re)(re)(re)和散(san)熱(re)(re)(re)(re)(re)情況有關(guan)，因而其(qi)維持(chi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(ihold)、動(dong)作(zuo)(zuo)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(itrip)及動(dong)作(zuo)(zuo)時(shi)(shi)間受環(huan)(huan)(huan)境溫度影響(xiang)。當(dang)環(huan)(huan)(huan)境溫度和電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流處于(yu)a區(qu)時(shi)(shi)，熱(re)(re)(re)(re)(re)敏(min)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)(zu)發熱(re)(re)(re)(re)(re)功率大于(yu)散(san)熱(re)(re)(re)(re)(re)功率而會動(dong)作(zuo)(zuo);當(dang)環(huan)(huan)(huan)境溫度和電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流處于(yu)b區(qu)時(shi)(shi)發熱(re)(re)(re)(re)(re)功率小(xiao)于(yu)散(san)熱(re)(re)(re)(re)(re)功率，高(gao)分子ptc熱(re)(re)(re)(re)(re)敏(min)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)(zu)由于(yu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)(zu)可恢(hui)(hui)復，因而可以重復多次使用(yong)。圖6為熱(re)(re)(re)(re)(re)敏(min)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)(zu)動(dong)作(zuo)(zuo)后，恢(hui)(hui)復過程中(zhong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)(zu)隨時(shi)(shi)間變化。電(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)(zu)一般在十幾秒到(dao)幾十秒中(zhong)即可恢(hui)(hui)復到(dao)初始值1.6倍左右的(de)水平，此時(shi)(shi)熱(re)(re)(re)(re)(re)敏(min)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)(zu)的(de)維持(chi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流已(yi)經恢(hui)(hui)復到(dao)額(e)定值，可以再次使用(yong)了。面(mian)積和厚(hou)度較(jiao)(jiao)小(xiao)的(de)熱(re)(re)(re)(re)(re)敏(min)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)(zu)恢(hui)(hui)復相(xiang)對(dui)(dui)較(jiao)(jiao)快(kuai);而面(mian)積和厚(hou)度較(jiao)(jiao)大的(de)熱(re)(re)(re)(re)(re)敏(min)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)(zu)恢(hui)(hui)復相(xiang)對(dui)(dui)較(jiao)(jiao)慢。

基本特(te)(te)性：熱(re)(re)敏(min)(min)電(dian)阻的電(dian)阻-溫(wen)(wen)度(du)特(te)(te)性可(ke)(ke)近似地用(yong)下式表示:R=R0exp:R:溫(wen)(wen)度(du)T(K)時(shi)的電(dian)阻值(zhi)(zhi)(zhi)、Ro:溫(wen)(wen)度(du)T0、(K)時(shi)的電(dian)阻值(zhi)(zhi)(zhi)、B:B值(zhi)(zhi)(zhi)、*T(K)=t(ºC)+273.15。實際上，熱(re)(re)敏(min)(min)電(dian)阻的B值(zhi)(zhi)(zhi)并非(fei)是恒定的，其變化大小(xiao)因材料構(gou)成而(er)異，大甚至可(ke)(ke)達5K/°C。因此在(zai)較大的溫(wen)(wen)度(du)范圍內應(ying)用(yong)式1時(shi)，將與實測值(zhi)(zhi)(zhi)之間存在(zai)一定誤差(cha)。此處(chu)，若將式1中的B值(zhi)(zhi)(zhi)用(yong)式2所示的作為(wei)溫(wen)(wen)度(du)的函數計算(suan)時(shi)，則可(ke)(ke)降低與實測值(zhi)(zhi)(zhi)之間的誤差(cha)，可(ke)(ke)認為(wei)近似相等(deng)。

BT=CT2+DT+E，上式(shi)中，C、D、E為常(chang)數。另(ling)外(wai)，因生(sheng)產條件不同(tong)造(zao)成的B值(zhi)的波動會引起常(chang)數E發生(sheng)變化(hua)，但常(chang)數C、D不變。因此，在探討B值(zhi)的波動量時，只需考慮常(chang)數E即可。常(chang)數C、D、E的計算，常(chang)數C、D、E可由(you)4點的(溫度、電阻值(zhi))數據(T0,R0).(T1,R1).(T2,R2)and(T3,R3)，通過式(shi)3~6計算。首先由(you)式(shi)樣3根據T0和T1,T2,T3的電阻值(zhi)求出B1,B2,B3，然(ran)后(hou)代(dai)入(ru)以下(xia)各(ge)式(shi)樣。

電(dian)(dian)(dian)阻(zu)值(zhi)計算例:試根(gen)據電(dian)(dian)(dian)阻(zu)-溫度特性表，求(qiu)(qiu)25°C時的(de)電(dian)(dian)(dian)阻(zu)值(zhi)為5(kΩ)，B值(zhi)偏差為50(K)的(de)熱敏電(dian)(dian)(dian)阻(zu)在10°C~30°C的(de)電(dian)(dian)(dian)阻(zu)值(zhi)。步驟(1)根(gen)據電(dian)(dian)(dian)阻(zu)-溫度特性表，求(qiu)(qiu)常數(shu)C、D、E。To=25+273.15T1=10+273.15T2=20+273.15T3=30+273.15(2)代入(ru)BT=CT2+DT+E+50，求(qiu)(qiu)BT。(3)將數(shu)值(zhi)代入(ru)R=5exp，求(qiu)(qiu)R。*T:10+273.15~30+273.15。

技術參數：①標稱阻值(zhi)(zhi)Rc:一(yi)般指環境溫(wen)度為25℃時(shi)熱(re)敏(min)電(dian)阻器(qi)的(de)實際(ji)電(dian)阻值(zhi)(zhi)。②實際(ji)阻值(zhi)(zhi)RT:在一(yi)定(ding)的(de)溫(wen)度條件(jian)下所測得(de)的(de)電(dian)阻值(zhi)(zhi)。

③材料常(chang)數:它是一(yi)個描述熱(re)敏(min)電阻材料物理特性(xing)的(de)參數，也是熱(re)靈敏(min)度指標，B值越(yue)大，表示熱(re)敏(min)電阻器的(de)靈敏(min)度越(yue)高(gao)。應(ying)注意的(de)是，在實際工(gong)作時，B值并非(fei)一(yi)個常(chang)數，而是隨溫度的(de)升高(gao)略有增加(jia)。

④電阻(zu)溫(wen)度(du)系數αT:它(ta)表(biao)示(shi)溫(wen)度(du)變化1℃時的阻(zu)值變化率(lv)，單位為%/℃。

⑤時(shi)(shi)間(jian)常數τ:熱(re)敏(min)(min)電(dian)阻(zu)器(qi)是(shi)有熱(re)慣性(xing)(xing)(xing)的(de)(de)(de)，時(shi)(shi)間(jian)常數，就是(shi)一個(ge)(ge)描述(shu)熱(re)敏(min)(min)電(dian)阻(zu)器(qi)熱(re)慣性(xing)(xing)(xing)的(de)(de)(de)參數。它的(de)(de)(de)定(ding)(ding)義(yi)為(wei)，在無功耗(hao)的(de)(de)(de)狀態下，當環境(jing)溫(wen)度(du)(du)(du)由一個(ge)(ge)特(te)定(ding)(ding)溫(wen)度(du)(du)(du)向(xiang)另(ling)一個(ge)(ge)特(te)定(ding)(ding)溫(wen)度(du)(du)(du)突然改變時(shi)(shi)，熱(re)敏(min)(min)電(dian)阻(zu)體的(de)(de)(de)溫(wen)度(du)(du)(du)變化了兩個(ge)(ge)特(te)定(ding)(ding)溫(wen)度(du)(du)(du)之差(cha)的(de)(de)(de)63.2%所需的(de)(de)(de)時(shi)(shi)間(jian)。τ越小，表明(ming)熱(re)敏(min)(min)電(dian)阻(zu)器(qi)的(de)(de)(de)熱(re)慣性(xing)(xing)(xing)越小。

⑥額定功(gong)率(lv)PM:在(zai)規(gui)定的(de)(de)技(ji)術條件下，熱敏(min)電阻器(qi)(qi)長期連(lian)續負載(zai)所(suo)允許(xu)的(de)(de)耗(hao)散功(gong)率(lv)。在(zai)實際使(shi)用時不(bu)得超過(guo)額定功(gong)率(lv)。若熱敏(min)電阻器(qi)(qi)工(gong)作的(de)(de)環境溫度(du)超過(guo)25℃，則(ze)必須(xu)相應降低其(qi)負載(zai)。

⑦額(e)定(ding)工(gong)(gong)作電流IM:熱敏電阻器在工(gong)(gong)作狀(zhuang)態下規定(ding)的(de)名義電流值。

⑧測量功率(lv)Pc:在(zai)規定的(de)環境溫度下，熱(re)敏電(dian)阻體(ti)受測試電(dian)流(liu)加(jia)熱(re)而引(yin)起的(de)阻值變化不(bu)超過(guo)0.1%時所消耗的(de)電(dian)功率(lv)。

⑨大(da)電(dian)(dian)(dian)(dian)壓(ya):對于(yu)NTC熱(re)敏(min)電(dian)(dian)(dian)(dian)阻器(qi)，是指在(zai)規(gui)定(ding)的(de)環(huan)境溫度(du)(du)下(xia)，不使熱(re)敏(min)電(dian)(dian)(dian)(dian)阻器(qi)引(yin)起熱(re)失控所允許連(lian)續(xu)施加的(de)大(da)直流電(dian)(dian)(dian)(dian)壓(ya);對于(yu)PTC熱(re)敏(min)電(dian)(dian)(dian)(dian)阻器(qi)，是指在(zai)規(gui)定(ding)的(de)環(huan)境溫度(du)(du)和(he)靜止(zhi)空氣中，允許連(lian)續(xu)施加到熱(re)敏(min)電(dian)(dian)(dian)(dian)阻器(qi)上(shang)并保證熱(re)敏(min)電(dian)(dian)(dian)(dian)阻器(qi)正常工作在(zai)PTC特性(xing)部分的(de)大(da)直流電(dian)(dian)(dian)(dian)壓(ya)。⑩高(gao)工作溫度(du)(du)Tmax:在(zai)規(gui)定(ding)的(de)技(ji)術(shu)條件下(xia)，熱(re)敏(min)電(dian)(dian)(dian)(dian)阻器(qi)長期連(lian)續(xu)工作所允許的(de)高(gao)溫度(du)(du)。

⑾開關溫度(du)(du)tb:PTC熱敏電(dian)(dian)阻(zu)(zu)器的(de)電(dian)(dian)阻(zu)(zu)值開始(shi)發生躍增時的(de)溫度(du)(du)。

⑿耗散系數H:溫度增加1℃時，熱(re)敏電(dian)阻器所耗散的功(gong)率，單位為mW/℃。

熱(re)敏(min)電(dian)(dian)(dian)(dian)阻(zu)也(ye)可(ke)作為電(dian)(dian)(dian)(dian)子線(xian)路(lu)元件用(yong)于儀表線(xian)路(lu)溫(wen)(wen)度補(bu)償(chang)和溫(wen)(wen)差(cha)電(dian)(dian)(dian)(dian)偶冷(leng)端溫(wen)(wen)度補(bu)償(chang)等。利(li)用(yong)NTC熱(re)敏(min)電(dian)(dian)(dian)(dian)阻(zu)的(de)(de)自(zi)熱(re)特性(xing)可(ke)實現自(zi)動(dong)(dong)增(zeng)益(yi)(yi)控制(zhi)，構成(cheng)(cheng)RC振蕩器穩幅電(dian)(dian)(dian)(dian)路(lu)，延遲電(dian)(dian)(dian)(dian)路(lu)和保護電(dian)(dian)(dian)(dian)路(lu)。在(zai)自(zi)熱(re)溫(wen)(wen)度遠(yuan)大于環(huan)境溫(wen)(wen)度時(shi)阻(zu)值還與(yu)環(huan)境的(de)(de)散熱(re)條(tiao)件有關(guan)，因此(ci)在(zai)流速計、流量計、氣體分析(xi)儀、熱(re)導分析(xi)中常利(li)用(yong)熱(re)敏(min)電(dian)(dian)(dian)(dian)阻(zu)這(zhe)一特性(xing)，制(zhi)成(cheng)(cheng)的(de)(de)檢測元件。PTC熱(re)敏(min)電(dian)(dian)(dian)(dian)阻(zu)主要(yao)用(yong)于電(dian)(dian)(dian)(dian)器設備的(de)(de)過熱(re)保護、無觸(chu)點(dian)繼電(dian)(dian)(dian)(dian)器、恒(heng)溫(wen)(wen)、自(zi)動(dong)(dong)增(zeng)益(yi)(yi)控制(zhi)、電(dian)(dian)(dian)(dian)機啟動(dong)(dong)、時(shi)間延遲、彩色電(dian)(dian)(dian)(dian)視自(zi)動(dong)(dong)消磁(ci)、火災報警和溫(wen)(wen)度補(bu)償(chang)等方面。

熱敏(min)電阻合(he)金已開始日益廣(guang)(guang)泛地用(yong)于溫度的監測和(he)撞制。如在(zai)環境監測、食品的長期儲存、生物工程以及*軍事工程等方面都獲得了(le)廣(guang)(guang)泛的應用(yong)。

熱(re)敏電(dian)(dian)阻合(he)金一般均具有(you)較(jiao)高的(de)(de)(de)電(dian)(dian)阻率和電(dian)(dian)阻溫(wen)度系數，因此(ci)可(ke)以(yi)制成小型(xing)化的(de)(de)(de)高靈敏度的(de)(de)(de)測溫(wen)傳(chuan)(chuan)感器(qi)。如(ru)箔式應變片式測溫(wen)傳(chuan)(chuan)感器(qi)就是一種理想的(de)(de)(de)結構件溫(wen)度測景(jing)元件。此(ci)外熱(re)敏電(dian)(dian)阻合(he)金在高性能飛機的(de)(de)(de)大氣總溫(wen)傳(chuan)(chuan)感器(qi)和大型(xing)客(ke)機溫(wen)度傳(chuan)(chuan)感器(qi)中也獲得了一定的(de)(de)(de)應用(yong)。可(ke)見(jian)，熱(re)敏電(dian)(dian)阻合(he)金的(de)(de)(de)優越(yue)性將日趨顯著。