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Explanation of Several Errors of Temperature Sensor in High and Low Temperature Alternating Humidity and Heat Test Chamber

January 3, 2024

     The high and low temperature alternating damp heat test box reproduces the high and low temperature environment through heating and cooling. The test box has a temperature sensor that transmits temperature. The temperature sensor is mainly used to sense the temperature change and convert it into a digital display.

Regarding the display accuracy of the temperature sensor of the high and low temperature alternating damp heat test box, it is mainly     reflected in the link of installation and use. The following editor will explain in detail:


1. Errors introduced by insulation deterioration


If the thermocouple is insulated, too much dirt or salt slag on the protective tube and pull-out plate will cause poor insulation between the thermocouple poles and the furnace wall, which is more serious at high temperatures, which will not only cause the loss of thermoelectric potential but also introduce interference.


2. Errors introduced by thermal inertia


Due to the thermal inertia of the electric couple, the indicator value of the meter lags behind the change of the measured temperature, and this effect is particularly prominent during rapid measurement.


3. Thermal resistance error


At high temperature, if there is a layer of coal ash on the protective tube and dust is attached to it, the thermal resistance will increase and hinder the heat conduction. At this time, the temperature indication will be lower than the true value of the measured temperature.


4. Errors introduced by improper installation


The thermocouple should not be installed too close to the door and heating, and the depth of insertion should be at least 8-10 times the diameter of the protective tube;

The pores between the thermocouple protection tube and the furnace wall should be blocked with insulating materials such as polyurethane foam or asbestos to prevent the convection of hot and cold air from affecting the accuracy of temperature measurement.