## 4 Implementation and Applications  
Once the corresponding preliminary tests had been successfully carried out to ascertain its correct operation, the system has been deployed in a scenario to evaluate its performance.  
The performance of the system has been tested at a meat-processing factory, where there are several machines with high energy consumption. This factory covers 28,000 m\({}^{2}\) and it has 300 employees. It processes 13 million kilos of meat per year, 30% of which are exports, with a billing that amounts to 55 million euros.  
In this case, the WSAN was implemented with a coordinator and several router nodes, distributed according to coverage and functionality requirements. The nodes were attached to several slicing and packaging machines, cooling chambers, ovens, electric vehicles charging stations and air-conditioning machines. For the energy efficiency analysis of the plant, the system measured voltage and current at machinery, as well as environmental temperature and humidity in several workrooms and outdoors. For the power supply management of the machinery, the outputs of the nodes were connected to relays, which operated the power supply of specific equipment.  
A set of tests was performed to the system once it had been deployed in the factory and before allowing it to start managing energy and controlling machinery. First, all sensors of each device were calibrated to provide reliable data from each sample. Later, the nodes were submitted to several coverage tests and it was ascertained that the indoors distance between nodes could be set at up to 230 m, as when nodes were further apart it was found that considerable amount of interferences distorted the signal. However, more than 600 m could be easily reached for outdoors scenarios. This big difference indoors-outdoors can be justified by the thick layers of isolation used for temperature controlled rooms. It was also concluded that no information packages were lost in the WSAN when nodes were located within the established distance from each other.  
An example of how the system works is shown in Figure 10, where a battery charging stage of an electric forklift was monitored and controlled. In this case, the charging process started when wind energy production was increasing and it was interrupted when the wind energy contribution decreased. The process started again each time that wind energy production increased and was  
Figure 9: Graphical examples of the HMI.  
interrupted when it decreased. But several minutes after five o'clock in the morning, the process was not interrupted when the wind energy contribution decreased because the time constraint was mandatory and it established that the battery had to be charged to a certain level (13.5 V) by 8:00 a.m. For this experiment, the battery voltage was monitored by one of the WSAN nodes and compared by the control system with the wind energy generation data as made available in real time by the energy supplier [44].  
Apart from this type of industrial scenario the system, being low-cost and non-intrusive, can also be deployed in residences, where it can control the air-conditioning and the main electrical appliances, such as the oven, dishwasher, fridge and washing machine.