Storm detection, a key complement to external protection

Local detection of lightning storms makes it possible to supplement and refine permanent protection, as it cannot prevent all the effects of lightning. The implementation of permanent protection together with preventive measures continuously reduces the number of deaths and injuries caused by lightning.

Lightning protection systems do not offer total safety: it is generally accepted that no space can be completely protected against lightning strikes. Even when external (lightning arresters) and internal (surge protectors) are present in a given area, it is necessary to reduce the risk of an accident to a level considered acceptable by the regulations in force1.

Temporary preventive measures are taken upon warning of a lightning strike risk and are deactivated once the danger has passed. Some preventive measures that can be taken are evacuation (moving or keeping people in a safe place), disconnection of the power supply line, stopping or postponing hazardous activities, alerting emergency teams (e.g. fire brigade, on-call service personnel), and other temporary measures specific to each type of industry. Preventive protection never replaces external protection, but complements and enhances it. Moreover, there are cases where external protection cannot be installed, so that preventive protection may be the only option to minimise risks and consequences of lightning strikes. In other situations, even if the external and internal protection is adequate, additional measures are still necessary. Further details of IEC 62793:2020 “Protection against lightning – Storm Warning System “2 will now be discussed.

Preventive protection never replaces permanent protection, but complements it by providing real-time information on the risk of lightning strikes

Storm detectors: what does IEC 62793:2020 say?

IEC 62793:2020 standard contains application guidance for considering the need to install a storm detection system as a warning to trigger temporary preventive measures. According to the standard, different types of losses must be taken into account: loss of life or damage to people, economic losses due to damage to property, economic losses due to lack of continuity of services, and environmental losses and damage. The standard identifies the following as hazardous situations:

  1. Gatherings of people in open areas for activities such as maintenance, work, sports, competitions, agricultural, livestock and fishing activities or mass events.
  2. Wind farms, large solar farms, supply lines.
  3. Occupational health and safety prevention.
  4. Safekeeping of sensitive assets: computer systems, electrical or electronic controls, alarm, security or emergency systems.
  5. Losses in industrial operations or processes.
  6. Storage, processing and transport of hazardous substances (flammable, radioactive, toxic or explosive).
  7. Certain environments or activities with a special risk of electrostatic discharge (e.g. spacecraft and flight operations).
  8. Basic services whose continuity, quality or rapid recovery must be guaranteed: telecommunications, energy generation, transport or distribution, health or emergency services.
  9. Infrastructures: ports, airports, railways, roads, motorways, etc.
  10. Environmental civil protection: prevention of forest fires, floods, etc.
  11. Large networks (e.g. power supply lines, telecommunication lines).
  12. Effects to third parties (e.g. power supply lines due to an impact on the substation feeding it).
  13. Workplace safety (activities involving risk at work in the event of a storm).

In addition, the standard specifies that a storm detector must be used when the safety of people is compromised in the event of a lightning strike.

The detection of lightning storms in the area complements external and internal protection by providing real-time information on the risk of lightning strikes. This is especially useful for decision-makers (state, local administration, private or public companies) in order to protect people and property from the adverse effects of thunderstorms.

IEC 62793:2020 standard considers the need to install a storm detection system, because permanent protection cannot prevent all lightning effects.

The IEC 62793:2020 standard covers two types of detectors: those based on electromagnetic field and those based on electrostatic field. The only ones that are capable of detecting all phases of the storm, from the initial phase to the dissipation phase, are electrostatic field sensors. This is because electromagnetic field-based detectors measure the electromagnetic radiation produced by lightning, so they need a discharge to be able to warn of the risk in an area. Once detected, they can establish their location and, based on the distance to the target to be protected, emit a risk warning. This type of detector assumes that further discharges will occur and that these discharges will continue to approach, when this is not always the case. If the first discharge occurs over the area, either because the storm forms directly overhead or because it approaches without producing any discharge, they will not provide a hazard alert and preventive measures cannot be triggered.

In addition, there is a further limitation of electromagnetic field-based detectors: they have no ability to determine the absence of risk when the storm dissipates or moves away, as they simply use a countdown from the last detected discharge. However, the risk may still be present, with danger to human lives, or may have disappeared before the predetermined countdown time.

The measurement of the surrounding electrostatic field by electrostatic field sensors eliminates all of the above limitations of electromagnetic field-based detectors.

ATSTORM® storm detector

ATSTORM® is a local warning system used to prevent the risk of lightning storms that detects thunderstorms in the area. It is controlled remotely by expert personnel from Aplicaciones Tecnológicas S.A. and is the most complete thunderstorm detector available, the result of more than 15 years of accumulated experience. It’s part of the Smart Solutions product range, commitmed to transform lightning protection installations through smart technologies.

Its alerts rely exclusively on the measurement of the ambient electrostatic field, the only direct and unambiguous indicator of the risk of lightning strike before any discharge occurs. ATSTORM® detects all phases of thunderstorm development as defined in IEC 62793:2020. Using the electric field variations produced by thunderstorms forming over the target and/or active thunderstorms up to a radius of 20 km, ATSTORM® technology provides tens of minutes of anticipation before the first lightning strike could be detected by the electromagnetic field reading. The objective measurement of the electrostatic field makes it possible to avoid unnecessary shutdowns sometimes produced by electromagnetic field based detectors, and also to adjust the shutdown time to the strictly necessary.

The ATSTORM® early warning system detects all phases of thunderstorm development, providing sufficient lead time to take the necessary preventive measures.

However, ATSTORM® also incorporates an electromagnetic sensor as a complement to monitor the approach of the storm up to a radius of 40 kilometres. Thus, the monitoring area is extended and a pre-warning status can be defined for distant active storms approaching the target to be protected.

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If you wish to know more about the application cases of the IEC 62793:2020 standard and our ATSTORM® storm detector, do not hesitate to contact us via this link.


  1. Horváth, T. Standardization of lightning protection based on the physics or on the tradition? J. Electrostat. 60, 265–275 (2004).
  2. International Electrotechnical Commission (IEC). IEC 62793:2020 Protection against lightning – Thunderstorm warning systems. International Standard (2020).