Thanks to the 868 MHz transmission frequency, the transmitted signals do not interfere with other wireless networks, especially with WiFi and Bluetooth networks that operate on a different frequency (2.4GHz). Furthermore, in plant built so far we have had the confirmation that there are no limitations due to interference with other electromechanical devices present on plants, in particular with industrial production machines.

In a wireless Mesh Network each node receives, regenerates and retransmits received signals. This allows you to create alternative routes in order to reach all the nodes of the system, making it extremely robust even in case of failure of some of the nodes installed. Furthermore, thanks to the Mesh Network, it is possible to extend the overall coverage area of the wireless network, exceeding the limit relating to the maximum transmission distance between two nodes. The advantage is evident, for example, in Street Lighting applications, where all nodes follow the road layout creating an extended path over the territory. ZETAQLAB systems control the number of repetitions (HOP) implemented by each node, in order to limit the complexity introduced by useless signal retransmissions.

All transmitted data are encrypted with symmetrical technology and are inaccessible to other devices that may be listening.

The maximum (real!) distance in optical visibility between two wireless nodes equipped with a stylus antenna is 300m. In indoor applications, when the antenna is wired and integrated in the nodes, this distance is reduced to about 100m. Thanks to Mesh Network technology, the coverage area of the wireless network can be extended, using up to 8 signal regenerations. In indoor applications, for example, in an industrial area of about 6,000 square meters, we have verified that with a maximum of one or two regenerations it is possible to reach all the nodes.

Lighting devices are typically not “dimmable”, it’s only possible to execute on and off commands by acting on the power supply. To take advantage of benefits of a control system, the light points must be equipped with a technology that make possible to regulate their light intensity. In this case, a luminaire is “dimmable”. The technologies to achieve this regulation are described in the article “Technologies for light management”.

DALI (Digital Addressable Lighting Interface) regulation technology, described in the article Technologies for light management, allows individual control of up to 64 DALI nodes wired on a bus. However, this requires assigning a unique address for each node (typically a lighting device) during the initial configuration of the system. This procedure is known as DALI “addressing” or “mapping” and is very time consuming. Furthermore, the system integrator that carry out the mapping cannot proceed with the configuration of the entire system until each node has been correctly mapped. It often has to wait that the installer solves all wiring errors, taking extra time compared to his normal work. In the same way, when a DALI device has to be replaced because it is defective, its (re)mapping and reconfiguration of the system is necessary, this is an operation that the maintenance technician or installer typically cannot do. In general, an “addressed” DALI system is very expensive in terms of commissioning and maintenance. Using the “broadcast” type of DALI command, on the other hand, it is not necessary to address the nodes because all the DALI devices connected on the bus will execute the command without distinction between them. We lost the possibility of managing univocally each single light point, but the initial configuration of the system and maintenance are enormously simpler, faster and cheaper.

To automate a lighting system and save energy, it is possible to take advantage of the contribution of natural light by reducing the luminous flux thanks to a brightness sensor. This technology allows you to save at least 30%, even when the contribution of sunlight is not high. When the illuminated area is involved in a discontinuous way, for example in a warehouse or an office, it is useful to avoid that the luminaires remain switched on at high intensity when no one is present. In these cases it is possible to use a motion sensor which, combined with a control system, can reduce or eliminate the luminous flux.

A brightness sensor can work in two modes. The first is commonly associated with the “twilight” function, whereby the sensor detects the intensity of natural light and is activated when it falls below a fixed threshold. This is an “open loop” control because the sensor is affected only by natural light and not by artificial light emitted by the luminaires. When you want to achieve a constant adjustment of the light intensity on a surface, for example the work surface, the sensor is installed on the ceiling in order to “read” the sum of the contribution of natural and artificial light reflected from the underlying surface. In this way it’s possible to realize a “closed loop” control, in which as the natural contribution varies, the system adjusts the artificial one with the result of keeping the sum of the two constant on the working plane. In order to make this control efficient it is necessary that the sensor is not blinded by natural light and is not influenced by the contribution of luminaires not managed by the sensor itself.

The “closed loop” brightness control allows you to keep a constant level on the work surface, for example 500 Lux on a desk in an office. To this end it is necessary to memorize the reference in the sensor, that corresponds to a value of incident light on the sensor (reflected from the desk) proportional to 500 Lux desired. This operation is called “calibration”. The incident value is affected by the construction characteristics of the room and the installation height of the sensor.

The motion sensors on the market are typically made with PIR (Passive InfraRed) technology. These sensors allow to detect the temperature difference between a moving body and the background surface. The sensor lens (Fresnel) allows to divide the controlled area into many small areas, called “clusters”, that are more small if the sensor have a sensitivity suitable for detecting small movements. The sensor turns on when it detects a temperature difference between two adjacent clusters. The energy saving obtained by introducing a motion sensor in the system depends on the degree of occupation of the controlled area. More the area is involved in a discontinuous way, lower the energy consumption will be.

The energy saving obtained thanks to the adoption of a control system equipped with light and movement sensors depends on the conditions of use of the plant, which unfortunately cannot be defined before. Considering our experience we can safely say that the saving obtained vary from a minimum of 30% to over 50%. For an accurate estimate, the TCOlight software based on the EN15193 standard is available, that allows you to use the LENI indicator (Light Energy Numeric Indicator) to evaluate the impact on consumption of both appliances and control systems. TCOlight also allows you to calculate the TCO (Total Cost of Ownership) and the payback time.