The working principle of the purification hot air circulation oven: When the temperature reaches the set value, the temperature controller outputs a PID control signal PLC, The PLC outputs a control signal to the time relay KT to start insulation timing, while closing the inlet fan and exhaust disc valve. By controlling the electric heating continuously through PID, the box is in the hot air circulation insulation stage. When the insulation time reaches the set value, the time relay outputs a signal to the PLC, The PLC outputs fully closed electric heating, opens the water cooling solenoid valve to make it engage and conduct, thus putting the box in the cooling and cooling stage.
The temperature control of the box adopts the GCD-23A intelligent computer temperature control and PLC automatic control system. The temperature signal is collected using a platinum resistor, and the PID control signal is obtained by comparing the amplification and setting values of the temperature controller. At the same time, the PLC program controller outputs a control signal to control the conduction of the solid-state relay SSR, and the solid-state relay controls the heating of the heater to put the box in the heating and dehumidification stage.
When the temperature inside the box drops by ≤ 40 ℃, the temperature controller outputs a control signal to the PLC, The PLC outputs to shut down the hot air circulation fan, and the drying cycle program ends. The TEED-2001K over temperature alarm temperature controller outputs a signal to control the operation of the entire PLC program. The platinum resistance PT100 test signal is sent to the alarm temperature controller to compare with the set temperature value for over temperature alarm. When the actual temperature value is lower than the set value, the control signal is output to the PLC, The PLC program is running normally. When the actual temperature value exceeds the set value, output a control signal to the PLC, The PLC shuts down the running program. Therefore, the set value of the over temperature alarm should generally be higher than the set value of the working temperature.
