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The ΔT is the early streamer emission of an ESE lightning arrester, which is obtained by a test in a high voltage laboratory. The test conditions are described in Annex C of the NF C 17-102: 2011, UNE 21186: 2011 and NP4426: 2013 standards.
According with NFC 17-102: 2011, UNE 21186: 2011 and NP4426: 2013 standards, in its point 5.2.2 and C.2.2 indicates that a lightning rod to be considered an ESE lightning rod, must obtain a ΔT at least of 10 microseconds, and the maximum permissible value of (ΔT) is 60μs, although in the test have obtained superior results.
The tip of an ESE lightning rod should be located at least 2m above the protected area, including antennas, cooling towers, roofing, reservoirs, etc.
As the maximum permissible value for ΔT following the standards is 60μs, the maximum protection radius calculated may not exceed of 120m in Level IV protection.
Using the risk calculation indicated in the Annex A of the NFC 17-102: 2011, UNE 21186: 2011 and NP 4426: 2013.
In our website there is an INGESCO Software Design, which is an online program that it allows to calculate the risk assessment and also make a totally free report with GOOGLE MAPS.
The protection levels of an ESE lightning rod are the safety factors to be applied to minimize the risk of damages due lightning strikes on a structure. Protection levels for lightning protection have a range from Level I to Level IV. Being the Level I the strictest level and the level that provides a greater efficiency.
Yes, you must connect the metallic elements that exist on the roof the structure with the external lightning protection system to avoid creating sparks or dangerous step voltages. This electrical connection of the metal mass can be done directly, or better by a protective spark gap.
The NFC standards 17102: 2011, UNE 21186: 2011 and NP4426: 20131 indicate that each PDC must be connected to at least two down conductors.
Table of materials accepted under current regulations:
Two downspouts are considered independent if they do not run parallel, parallel understood as a straight line distance of less than 2m between conductors.
Yes, when is not possible to be done outside and the cable goes down within a specific insulating conductive and non-flammable.
The lightning counter installation is necessary to know when the installation has received the lightning strike and thus perform the verification of lightning rods and grounding.
You only need to install a lightning counter for installation regardless of the number of down-conductors to earth disposal, the equipment also account for the impact of lightning on the system.
Yes, the exterior steel trusses interconnected (metal structures) can be used as natural drainpipes of external protection systems against lightning, provided that its conductivity is ensured and its impedance is less than or equal to 0.01 Ω.
A spark gap or ISG isolation (isolating spark gap) is 2 electrodes spaced a certain distance, in order to electrically insulate conductive installation sections. If lightning strikes the plant sections are temporarily connected as a result of response to discharge.
Yes, it is recommended to connect the two grounding systems to achieve an equipotential system throughout the facility.
Current standard indicates that "When the building or the protected volume has a foundation earth termination system for low voltage, the ESE earth termination systems should be connected to it with a standardised conductor (see EN 50164-2)."
For ESE lightning rod installations, the maximum resistance value is 10 ohms.
Table of materials accepted under current regulations:
Different devices for detecting storm and lightning detection, being the most commonly used technologies:
1. Electrostatic field meter. The field mill indicates the real-time measurement of the value of electrostatic field (V / m), this device is programmed to send alarms when there is risk of lightning strike. It allows us to know the evolution of the storm and make preventive measures before the first lightning strikes.
2. Electromagnetic pulse detectors. By installing multiple antennas, the exact location of the lightning strike is obtained. This information allows you to create predictive models to know which direction the storm can take to complete the necessary prevention measures.
UNE EN 50536: 2011 (Protection against lightning - Thunderstorm warning systems) explains how must be a correct prevention against lightning and determines the different existing detection systems. Is coming so to approve the IEC 62793 is the international version of the European 50536.
The measures taken are different depending on the type of installation and / or equipment that we have. Highlights include:
For the protection of living beings, in case of risk of lightning strikes in open areas, schools, sports facilities, amusement parks, golf courses, etc ... it is recommended to evacuate people in the exposed areas.
Industry should be disconnected from external power surges sensitive so that they are protected in case of falling on power lines ray equipment.
They are the appropriate protection to avoid the surge in the power supply system, communications or data system.
It’s an over voltage with a big magnitude, about tens of kV and with a short duration (microseconds). However, they have a highly destructive power on sensitive electronic equipment.
They arise mainly as a result of lightning strikes, switching in the networks and/or defects therein.
The lightning strikes in the distribution lines or close to, or the lightning strikes in external protection system located in the same building or nearby.
There are different rules and regulations, the most important are the RBT (ITC-BT-23), EN 61643-11: 2012, IEC 62305-4.
The SPD (surge protection devices), are intended to reduce the input surge to a lower value. This is accomplished with a strategy that integrates 3 protection levels: type 1, type 2 and type 3. Thereby achieving a low voltage level not dangerous for the electronic equipment.