Temperature regulator drying room temperature control circuit 2

The electric heater is 18 electric heating tubes with a total power of 45kW, which are divided into three groups and controlled by contactors
KMi, KMz and KM3 respectively. The drying room volume is 3m×l_5m×1.8m. Process requirements: The temperature must be kept within the range of 180℃±
5℃ for 30 minutes.
    When the temperature does not reach the set lower limit (175°C), the upper and lower limit normally closed contacts 3 and 1 of KP and contacts 3 and 2
are closed, while the lower limit normally open contacts 3 and 4 are opened, and the three sets of electric heating The devices EHi, EHz and EH3 are all put into heating. When the
temperature reaches the lower limit of 175°C, the lower limit normally open contacts 3 and 4 of KP are closed, and the normally closed contacts 3 and 1 are disconnected, leaving only a set of
electric heaters EHi for heating, and the power is only 1/1 of the original power. 3. When the temperature reaches the upper limit of 185°C, the upper limit contacts
3 and 2 of KP are disconnected and heating stops. When the temperature is lower than 175℃, the upper and lower limit normally closed contacts of KP are closed and full power
heating is entered again. When the temperature reaches 30nun within the range of 180℃±5c, the delayed opening normally closed contact of KT is disconnected, the KAI
loses power and is released, cutting off the power of all circuits and heating stops. At the same time, the electric bell HA buzzes to remind the staff that the heat preservation time
has expired and they need to take out the objects from the drying room. Press button SB4 to stop the whine.