# An IoT-Based System for Monitoring the Health of Guyed Towers in Overhead Power Lines
## 3 System Architecture
### Hardware Design of the System
#### 3.5.3 Sensors  
Cable tension sensor: The cable tension sensor is important because it is a straightforward way to verify whether the cable is loose or over-tight. The sensing device is a load cell to monitor the safety of cranes, rolling bridges, trolleys, and elevators. It is installed directly on the cable using screws and bolts without the need for cutting. The principle of operation consists of measuring the angle deviation over a \"V\" shape formed by the cable path on the mechanical structure of the cell. Thus, this method preserves the integrity of the cable because no cuts or exceeding deflections are necessary to achieve the cable tension measurement. The electronic side of the sensor relies on a Wheatstone bridge of 350 Ohms, and the load limit measurement ranges from 10.000 a 57.000 Kgf. Figure 8(a) shows the diagram of the sensor connected to the cable, and Figure 8(b) shows the actual tension sensor attached to the tower cable. Accelerometer and gyroscope: Measurement of displacement or configuration is essential for a guyed tower, particularly for a long-span structure, and there is no single perfect technology for the purpose. Nevertheless, an accelerometer is the most straightforward measure technology that converts mechanical motion into an electrical signal. Thus, it is an electromechanical device that measures acceleration forces, whether caused by gravity or motion. Concerning the gyroscope, the main difference is that it senses rotation, which is essential when strong winds cause rotational forces. The MPU6050 module is a three-axis acceleration sensor. It has angular velocity sensing ranges at \(\pm\)250, \(\pm\)500, \(\pm\)1000, and \(\pm\)2000\({}^{\circ}\)/s (dps). The accelerometer ranges are \(\pm\)2 g, \(\pm\)4 g, \(\pm\)8 g and \(\pm\)16 g. The MCU can communicate with the module through IIC interface pins, SCL and SDA. Temperature and humidity: The atmospheric corrosion of metallic materials causes tremendous economic losses every year worldwide. Thus, it is meaningful to predict corrosion loss in different field environments. Generally, the corrosion prediction method includes feeding a model of the corrosive environment with history data collected from long-term temperature and humidity variables. Then, temperature and humidity sensors are important in the task of predicting the guyed tower health. The HDC2010 is an integrated humidity and temperature sensor with very low power consumption. The motivation of choice is that the sensing element is on the bottom part of the device, making it more robust against dirt, dust, and other environmental contaminants. A second important feature is the heating element to dissipate condensation and moisture. The device supports a 1.8 V power supply voltage combined with programmable sampling intervals that leverage online time for battery-operated systems. The HDC2010 is factory-calibrated to 0.2 \({}^{\circ}\)C temperature accuracy and 2% relative humidity accuracy and includes a heating element to burn away condensation and moisture for increased reliability. The HDC2010 supports operation from \(-40\)\({}^{\circ}\)C to 125 \({}^{\circ}\)C and from 0% to 100% relative humidity. Ambient light: Depending on the amount of sunlight, the guyed tower can increase in size. It is a natural physical phenomenon called thermal expansion, where heat causes an increase in volume, making metallic structures increase by a few centimeters. That is why the amount of light must be monitored because it also contributes to the tower's tilt. In this way, the OPT3001 is the light sensor device included in the current framework. Furthermore, the light information of the region can help monitor the battery status, not letting the device die out of energy charge. The sensor's spectral response tightly matches the photopic response of the human eye and includes significant infrared rejection. The device's measurement range is from 0.01 up to 83 k lux, without selecting intermediate scales manually.