If the temperature of the thermal shock Test Chamber is overshoot, it will be more harmful to the tested samples during the start-up, heating, and heat preservation processes, especially the glued materials that are sensitive to temperature, which will lead to product damage or glued material failure. . So how to solve the problem of temperature overshoot in the thermal shock Test Chamber?
First explain what is temperature overshoot and temperature overshoot?
Temperature overshoot: When the equipment is heating up or cooling down to the specified temperature, the actual temperature of the working space exceeds the allowable range of the specified temperature.
Temperature overshoot: the amount by which the actual temperature of the working space exceeds the allowable range of the specified temperature during the heating or cooling of the equipment to the specified temperature.
Even if the overshoot temperature of the thermal shock Test Chamber exceeds the standard, the cooling unit and heating system software for the power supply of the Test Chamber assembly line should be installed. During the rapid cooling process, when the temperature of the box is close to the overall target temperature, the system software will turn on the electric heater and balance the cooling capacity caused by the refrigeration unit according to the heat generated by the electric heater. The purpose of orderly advancement and reduction of temperature negative overshoot. However, due to the limitations of the PID of the temperature controller and the calculation itself, usually only after a negative error occurs in the temperature, the heat output will increase rapidly, so it is easy to overshoot. Therefore, the refrigeration unit raises some intake valves, and opens different intake valves at different temperature points according to different temperature alarm points, so as to reduce the cooling capacity entering the box, thus avoiding the rapid heating and cooling process. overshoot condition.
The thermal shock Test Chamber divides the electric heaters into three groups to be operated separately, one group is controlled by the heat output of the temperature controller, and the other two groups are controlled by the PLC. Because in the process of rapid heating, when the temperature is close to the target, the PID transmission will reduce the output of the electric heater, which is also affected by the limitations of PID and calculation and the waste heat recovery of the electric heater. At this time, there will be excessive temperature. Chong situation. When approaching the target temperature, several groups of electric heaters are gradually lowered, thus effectively solving the overshooting situation of the rapid temperature change Test Chamber.
The electronic overheat protector of the thermal shock Test Chamber is independently installed on the main control board, and the temperature limit of the measured target can be set for maintenance. And in the hardware design, it is necessary to select the intermediate relay. According to the output of the thermostat and its temperature controller, the hydraulic control system of the intermediate relay is interoperated, and then the operation rules of the electric heater are considered. Because in the temperature control work, the temperature and humidity controller will control the frequent start and stop of the electric heater according to the fluctuation of the specific temperature of the box. Because the output power of the electric heater is very large, ordinary AC contactors cannot withstand frequent starts and stops.
