Wiring

During the wiring of the main power circuit, the provided EPLAN circuit diagram and VDE regulations were followed and adhered to.
The cables preceding the RCD over current protection combination were wired with orange-colored wires and marked with warning labels on the terminal strip. Additionally, all components were labeled with their corresponding designations taken from the circuit diagram. The terminals were secured with end stops to prevent any movement. The PE terminals were not interconnected as they have contact with the DIN rail. Measures were taken to ensure finger protection, preventing contact with live parts.

Wiring of the control circuit

The wiring of the control circuit also followed the provided EPLAN circuit diagram and VDE regulations. The control circuit was wired with a dark blue wire with a conductor cross-section of 0.75 mm2. The control circuit is responsible for controlling the fan. The fan is controlled via a contactor that can be switched on and off using two buttons. In the activated state, the contactor remains engaged until the normally closed contact is activated or the LS/FI combination trips.

Figure: Main power and control circuit, Fabio Bock

Wiring and programming of the light sensor and light source

The next step involves connecting the ESP32 and the BH1750 sensor according to the sensor's datasheet specifications. The SDA connection was made to the ESP32 pin GPIO21, and the SCL connection to GPIO22. After verifying the accuracy of the light measurements, it was determined that the BH1750 sensor was indeed more suitable. The LED for providing the light to be measured by the BH1750 in the final system was connected to the ESP32 using a 100 Ω resistor. A portion of the program code was then written to read the light sensor's values.

Wiring of the MOSFET and the heating cartridge

Next, the MOSFET is addressed. It is connected to the ESP32's GPIO12 pin as the signal pin and to 5V and ground. Additionally, the MOSFET is connected to the 24V switching power supply. The other two pins of the MOSFET are used to power the heating cartridge. To connect the heating cartridge, the contacts are joined with 0.75 mm2 diameter wires using heat shrink tubing. The wires are then connected to the MOSFET. It is irrelevant which contact is connected to the positive or negative terminal.