固定螺纹锥度热电阻，工业用热电阻分铂热电阻和铜热电阻两大类。热电阻是利用物质在温度变化时自身电阻也随着发生变化的特性来测量温度的。热电阻的受热部分（感温元件）是用细金属丝均匀地双绕在绝缘材料制成的骨架上。当被测介质中有温度梯度存在时，所测得的温度是感温元件所在范围内介质层中的平均温度。装配式热电阻主要由接线盒、保护管、接线端子、绝缘套管和感温元件组成，并配以各种安装固定装置。WZP型铂电阻的感温元件是一个铂丝绕组，双支铂电阻主要用于需要用二次显示、记录或调节仪同时检测同一地点温度的场合。WZC型铜电阻的感温元件是一个铜丝绕组。
热电阻测温原理
受热后的金属丝电阻随着温度的变化而变化，其热电阻值R(t)与其所处温度t的关系可表示为： R(t)=Ro(1+At+Bt2+------)按测得的电阻值查相应分度号表即可得出被测温度值t。或由显示仪表直接读出。
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.
