# Remote Low-Cost Differential Isolated Probe for Voltage Measurements
## 1 Introduction
The power supply system, together with no need for connection to a conventional oscilloscope, provides the galvanic isolation of the system. Finally, there are high-voltage isolated digital probes such as the one presented in [5]. This work presents a similar line to the previous one by applying isolation in the digital part of the system. Their target application is focused on electric cars and even the photovoltaic generation system. The specifications of the probe developed by these authors are \(\pm\)1500 V and a bandwidth of 1 MHz. To achieve these specifications, the probe uses an attenuation and conditioning stage at the input to match the voltage levels to an 18-bit ADC. It is at this point, in the communication between the ADC and the FPGA that acts as the data acquisition, control, and processing device, where the galvanic isolation is found. Finally, the data are sent via Bluetooth for their remote analysis and representation. As in the previous case, this device is not designed for connection to an oscilloscope or a conventional instrument. These developments show the increasing need for voltage measurements with isolated probes. Some of the developments already integrate Bluetooth connectivity to obtain such isolation and a remote connection to the probe. The growing need of specific instrumentation for its application in smart city environments, smart grids, etc., shows the need for continuous, remote, and unsupervised voltage monitoring, thus motivating the development of this work, that combines high-voltage monitoring devices and the IoT paradigm, requiring the proper management of network communication and computation, taking the CPS to the IoT path. The emergence of the Internet of Things is driven by the rapid expansion of the internet in the late 20 th century, which continued into the early 21 st century, leading now to a digitisation of the physical world around us and giving rise to the IoT. The term Internet of Things was introduced in 1999 by [PERSON] to denote the need to increase the number of microprocessors that interact with our surrounding physical world. IoT basically consists of a remote data exchange system that aims to provide new services in all areas of daily life [6]. The IoT can be found in many applications including agriculture, energy, industrial automation, transportation, smart cities, and power electronics converters [7; 8; 9; 10; 11]. Increasing advances in communications and sensor technology have encouraged the growth of the IoT, as well as a specialisation in its use for each type of application. This has led to the appearance of new terms such as Internet of Medical Things (IoMT) [12], Industrial Internet of Things (IIoT) related to Industry 4.0 [13], Internet of Energy (IoE) [8; 14], and others that could be found in the state of the art. The term IoE was coined for the first time in 2011 [15]. This gives an idea of the youth of the specialisation of the IoT paradigm in this type of applications, where it can be included topics such as smart grids and the quality of the electricity network measurement systems. More specifically, some of the applications where we can find IoE systems are the production of renewable energies, such as solar energy, in which in addition to measuring the grid, it is important to measure the environmental conditions [16]; the remote management and control of distributed microgrids [16; 17; 18; 19], allowing the generation processes to be controlled and monitored independently, but collaboratively; and energy management in smart buildings [20; 21], where in addition to measuring energy consumption, it is necessary to measure other distributed parameters of the building. In the primary structure of any IoT (and, hence, IoE) system, three different layers can be found: (i) the physical or sensor layer, (ii) the software control layer, and (iii) the application layer.