工業(yè)用熱電阻分鉑熱電阻和銅熱電阻兩大類。熱電阻是利用物質(zhì)在溫度變化時(shí)自身電阻也隨著發(fā)生變化的特性來測量溫度的。熱電阻的受熱部分（感溫元件）是用細(xì)金屬絲均勻地雙繞在絕緣材料制成的骨架上。當(dāng)被測介質(zhì)中有溫度梯度存在時(shí)，所測得的溫度是感溫元件所在范圍內(nèi)介質(zhì)層中的平均溫度。裝配式熱電阻主要由接線盒、保護(hù)管、接線端子、絕緣套管和感溫元件組成，并配以各種安裝固定裝置。WZP型鉑電阻的感溫元件是一個(gè)鉑絲繞組，雙支鉑電阻主要用于需要用二次顯示、記錄或調(diào)節(jié)儀同時(shí)檢測同一地點(diǎn)溫度的場合。WZC型銅電阻的感溫元件是一個(gè)銅絲繞組。
熱電阻測溫原理
受熱后的金屬絲電阻隨著溫度的變化而變化，其熱電阻值R(t)與其所處溫度t的關(guān)系可表示為： R(t)=Ro(1+At+Bt2+------)按測得的電阻值查相應(yīng)分度號(hào)表即可得出被測溫度值t?；蛴娠@示儀表直接讀出。
Industrial thermal resistance contains two categories, Pt thermal reistance and Copper thermal ressistance.
Thermal resistance is used to measure temperature on the basis of the property that substances’own resistance varies with the temperature. The part of the thermal resistance that is heated (temperataure-sensing element) is made by dual winding of fine wires around the frame made of insulation materials. When there is temperature gradient in the mediums to be measured, the measured temperature is the average temperature in the dielectric layer within the range where the temperature-sensing element is placed.Packaged thermal resistance consists of connection box, protectin tube, connection terminal, insulating sleeve and various fixed devices.WZP Pt resistance’s temperature-sensing element is a Pt wire winding. Double platinum resistance mainly is used fou such situation where it is required to use secondary display instrument, recorder and accommodometer to simultaneously detect the temperature of the same place. WZC copper resistance’s temperature-snesing element is a copper wire winding.
Temperature measurement principle of thermal resistance
The resistance of the metal wire that has been heated varies with the termperature, and the relation between the thermal resistance value and the temperature it is at can be expressed as R(t)=Ro((1+At+Bt2+------)According to the resistance value that is measured to refer to corresponding graduation mark, the temperature t that is measured can be come out, or read it directly from the indicating instrument.
