The ATSTORM® storm detection system, remotely operated by the experts at Aplicaciones Tecnológicas S.A., uses the dual technology of electrostatic field sensors and electromagnetic field-based sensors. The scanning of any environmental sensor can be interfered by any external element. The redundancy of ATSTORM® detection units allows to obtain a homogeneous alarm valid for the whole target area, thanks to the balanced auto-compensation of the obtained values that guarantees an exceptional accuracy.
IEC 62793:2020 “Lightning Protection – Storm Warning System “1 standard addresses the need for the installation of a thunderstorm detection system to prevent losses due to lightning strikes (loss or damage to people, economic losses due to damage to property and lack of continuity of services, and environmental losses and harms). The standard covers two categories of thunderstorm detectors: electromagnetic field-based sensors and electrostatic field-based sensors.
In both cases, these are environmental sensors whose interpretation can be interfered by any external element, whether nearby or not, that is not related to the parameter to be measured. Therefore, manufacturers must incorporate the appropriate filters and installation methods to minimise these interferences and increase the reliability and accuracy of the measurements. Electromagnetic and electrostatic field sensors used in storm detection systems are no exception. The installation of redundant detection units is necessary to ensure the proper functioning of the sensors and can also be used to improve warning criteria in terms of accuracy and precision.
Electromagnetic and electrostatic interference in storm detection
Electromagnetic field-based sensors measure the electromagnetic radiation produced by lightning, reliably detecting and locating lightning strikes. These sensors are usually found as part of large detection networks with sensors distributed over large areas and even around the world2. The redundancy of their units is necessary to detect discharges from thunderstorms, discriminating them from other electromagnetic radiation present in the environment, whether of natural or anthropogenic origin. Radio frequency signals from nearby elements (radio communications, electric motors, power transmission lines, switching, etc.) can confuse readings and generate false detections. Redundant sensors allow filtering out all this electromagnetic noise not caused by electrical storms.
The excess of signals in the electromagnetic spectrum requires electromagnetic field-based detectors to filter them to discriminate those that are produced by lightning.
In addition, the various redundant units of electromagnetic field-based sensors ensure the global operation of the detection network even if the sensors at a certain location are not operational at that time. The distance between these sensors can be 200-400 km, so they will not always have local sensors at a specific location, but may be located over long distances (more than 200 km).
Unlike electromagnetic field detectors, electrostatic field sensors are local, i.e. they are located in the area requiring protection. These sensors are based on the measurement of the ambient electrostatic field which undergoes a point variation from +100-150 V/m to tens of kV/m when going from good weather to stormy conditions3. False detections or failures of electrostatic field sensors to warn may be due to electrostatic field sources other than storm clouds, such as dust clouds or nearby items that become statically charged, distorting or shielding the field. These nearby elements that may be statically charged have to be taken into account in the installation of electrostatic field sensors to avoid their interference. In the case of dust clouds, they will only emit a warning if the field generated by them is very high, a situation in which electrical discharges can be generated, as is the case in deserts or even in ash clouds from erupting volcanoes. For this reason it is not correct to consider them as a false alarm. The sources of electrostatic noise are smaller than those of electromagnetic noise, so that the measured signals require less filtering than in electromagnetic field-based detectors. In addition, false alarms can be avoided by having several detection units in the area.
Electrostatic noise sources are not as abundant as those present in the electromagnetic spectrum. False alarms are avoided by redundancy of electrostatic field detection units.
Redundant detection units not only prevent false alarms from thunderstorms, but also improve the overall performance of the system and increase its accuracy, as is the case with the ATSTORM® local expert storm detection system.
ATSTORM® Lightning storm detection system
The ATSTORM® expert local storm detection system for lightning strike risk prevention features electromagnetic and electrostatic field sensors combined. This dual detection technology, together with Internet of Things (IoT) connectivity, makes it the most complete storm detection system currently available, as a result of the accumulated experience of more than 15 years.
Warning alerts for thunderstorm formation or approach within a 20 km radius are based exclusively on the measurement of the ambient electrostatic field, the only strong preventive measure because it detects all phases of the thunderstorm from initial to good weather as defined by IEC 62793:2020. Electrostatic field sensors are the only ones capable of determining the actual risk of lightning strike before a discharge occurs. It should be noted that ATSTORM®’s electrostatic field sensors are fully electronic and have no moving parts, which is a clear advantage over other conventional sensors.
The ATSTORM® expert system also incorporates an electromagnetic sensor that extends the monitoring area up to a radius of 40 kilometres, and a pre-warning state can be defined for distant active storms approaching the target to be protected.
The sensors of the various redundant units are permanently connected to Aplicaciones Tecnológicas, where their signal is processed, monitored and alerts are sent to customers via multiple channels. Remote control ensures the elimination of false alarms, as well as high accuracy. All collected and processed information is provided centrally for multi-location customers.
The installation of several ATSTORM® sensor units in a specific area provides a homogeneous alarm valid for the whole area and not only for the point where the individual sensors are installed, guaranteeing an unprecedented accuracy.
As is the case with electromagnetic field-based detector networks and electrostatic field sensors, the installation strategy of the ATSTORM® system consists of several detection units, the number and location of which is determined according to the location to be protected, taking into account its dimensions and the risk calculation. These redundant detection units provide a consistent alarm throughout the area to be protected, guaranteeing exceptional accuracy thanks to the balanced self-compensation of the measured values. As it is operated by experts, the proper functioning of the ATSTORM® system is guaranteed in any situation, allowing objective decision-making in the event of lightning strikes.
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References
- International Electrotechnical Commission (IEC). IEC 62793:2020 Protection against lightning – Thunderstorm warning systems. International Standard (2020).
- Rakov, V. A. Electromagnetic Methods of Lightning Detection. Surv. Geophys. 34, 731–753 (2013).
- Martinez-Lozano, M. Medición del campo eléctrico atmosférico en la ciudad de León. Establecimiento de límites para prevención ante la ocurrencia de descargas atmosféricas. (2014) doi:10.13140/2.1.3635.2323.