Non-Conventional Lightning Protection System – Part Two


In Article Types Of Lightning Protection Systems LPS ", I list the main types of Lightning Protection Systems as follows:




Types of Lightning Protection Systems LPS

Lightning protection systems for buildings and installations may be divided into three principal types as follows:

1- LPS for Protection for buildings and installations against direct strike by lightning, which includes:

A- Conventional lightning protection system, which includes:

  1. Franklin Rod LPS,
  2. Franklin/Faraday Cage LPS.


B- Non-Conventional lightning protection system, which includes:

a- Active Attraction LPS, which includes:

  1. Improved single mast system (Blunt Ended Rods),
  2. Early streamer Emission System.


b- Active Prevention/Elimination LPS, which includes:

  1. Charge Transfer System (CTS),
  2. Dissipation Array System (DAS).


2- LPS for Protection against overvoltage on incoming conductors and conductor systems,

3- LPS for Protection against the electromagnetic pulse of the lightning.






And, I explained the Conventional Lightning Protection System parts and components in the following Articles:



And in Article " Non-Conventional Lightning Protection System – Part One ", I explained the first type of Non-Conventional Lightning Protection System which is Active Attraction LPS, which includes:

  • Improved single mast system (Blunt Ended Rods),
  • Early streamer Emission System.


Today, I will explain the second type of Non-Conventional Lightning Protection System which is Active Prevention/Elimination LPS.



For more information, you can review the following Articles:






Non-Conventional Lightning Protection System





1- Components of Non-Conventional Lightning Protection System

Non-Conventional lightning protection system includes (2) main types as follows:

a- Active Attraction LPS, which includes:

  • Improved single mast system (Blunt Ended Rods),
  • Early streamer Emission System.


b- Active Prevention/Elimination LPS, which includes:

  • Charge Transfer System (CTS),
  • Dissipation Array System (DAS).








2- General Information About
Non-Conventional Lightning Protection System

  • In the 1970s, two types of unconventional air terminals had been commercially reinvented and introduced in the world market under a variety of trade names. They are:


1- The lightning Active Attraction air terminal: 

the lightning attracting air terminal is claimed to be able to attract the lightning to it (and hence away from the building) in order to protect the building that it was installed on.

 2- The lightning Active Prevention/Elimination air terminal:

 the lightning prevention air terminal is claimed to be able to prevent lightning from occurring and hence protect the building.

  • Some of the trade names for of unconventional air terminals are as follows:



Product Name
Country
Dynasphere
Australia
Prevectron
France
EF
Swiss
St. Elmo
France And Italy
Pulsar
France
DAT Controler
Spain
Paratonerre
France
Preventor
France And UK
EF33
Australia


  • In reality, the inventors of these un-conventional air terminals have never been able to provide any scientific basis for their invention. None of the “scientific papers” that they have published in the last 30 years have been independently verified by the scientific community.
  • In addition to this, these inventors have never been able to provide any independently validated proof that their inventions work. However, they have provided plenty of anecdotal (i.e. hearsay) evidence which had been obtained from “satisfied customers” and some insurance carriers will accept them as equivalent for the conventional techniques.
  • These Non-conventional air terminals are claimed to be superior to the conventional lightning protection but neither experimental data nor theory supports these claims.

  • For these reasons, these inventors and manufacturers have not been able to get their unconventional air terminals approved by the standards bodies like:

  1. NFPA,
  2. IEEE,
  3. IEC,
  4. US Military,
  5. UL.


  • Hence the LPS that used these Non-conventional air terminals have been classified as Non-standard LPS by academics, scientists and the various standards bodies around the world.
  • The Non-standard LPS are usually easier and cheaper to install when compared to the conventional system but the protection that it provides is very limited i.e. equivalent to that of a single Franklin rod! Hence these vendors had to rely on some very creative marketing to sell their non-scientific and unproven products.








Important Note

The volume or zone of protection afforded by the air termination system shall be determined only by the real physical dimension of the air termination system. Typically if the air rod is 5m tall then the only claim for the zone of protection afforded by this air rod would be based on 5m and the relevant Class of LPS and not any enhanced dimension claimed by some non-conventional air rods.






Second: Active Prevention/Elimination LPS






Important Note

In this Article, I will discuss the Active Prevention/Elimination LPS from the point of view of their proponents and in next articles; I will discuss the arguments against the claimed advantages of Active Prevention/Elimination LPS by their proponents.





1- Introduction

A large thunderstorm can produce over 100 lightning flashes a minute, A flash is defined as the ionized channel resulting from the lightning discharge; A stroke is one surge of current in that channel. Every strike has many effects on the struck facility or area, these effects can be categorized as follows:


1- Direct Effects

The direct effects of a lightning strike are physical destruction caused by the strike and subsequent fires. For example, when a direct strike hits a facility where flammable materials are present, the flammables may be exposed to either the lightning bolt itself, the stroke channel, or the heating effect of the lightning strike.

2- Secondary Effects

While the direct effects of a strike are obvious, the secondary effects can be just as devastating. This is especially true for electrical power lines and facilities with sensitive electronic equipment. The secondary effects of a direct or nearby strike include:

  • Electromagnetic pulse (EMP),
  • Electrostatic pulse,
  • Earth current transients,
  • Bound charge.


  • The bound charge (and subsequent secondary arc) is the most common.  The secondary effects are not always easily identified as to cause or mechanism.
  • Both direct and secondary effects must be minimized or eliminated by suitable Lightning Protection Technologies.






2- Differences in Lightning Protection Technologies


As we stated before, the most common LPS are:

  1. Conventional Lightning rods (sharp or blunt),
  2. Active Attraction LPS: Early streamer Emission System,
  3. Active Prevention/Elimination LPS: Charge Transfer System (CTS) and Dissipation Array System (DAS).


1- Conventional Lightning rods (sharp or blunt):

  • Protection against direct lightning strikes by the lightning rod is quite reliable, simple, passive (does not requires any power supplies), inexpensive, and does not require any maintenance.
  • Conventional protection will not influence any of the secondary effects other than to increase the risk of an event since Air terminals collect strikes and Heavy current of the lightning discharge flows through the lightning rod, grounding wire and grounding instead of the alternative path through the object protected by the lightning rod. The heavy returned lightning current in a stroke to the lightning rod produces a powerful electromagnetic wave, which induces in the nearby electrical/electronic circuits the dangerous voltages by far exceeding the safety level which can damage or “confuse” these circuits and their components.


2- Active Attraction LPS: Early streamer Emission System

  • An ESE terminal is equipped with a device that increases the probability that an initiated upward streamer will connect with a downward leader. Increasing this probability means that lightning is more likely to strike the terminal rather than unwanted areas.
  • So, An ESE is a similar technology to the lightning rod in two major aspects: 
  1. They collect lightning.
  2. The protected area suffers from the secondary effects related to the close proximity of the electrostatic and electromagnetic fields. They are dangerous to flammables, explosives, and electronics.


  • To minimize or eliminate these undesirable secondary effects, one of the following solutions must be followed:
  1. Using shielding, filtering and surge protection of the devices which might be affected,
  2. Providing conditions under which lightning either does not occur or cannot strike the protected structure instead of collecting the strikes,


3- Active Prevention/Elimination LPS: Charge Transfer System (CTS) and Dissipation Array System (DAS)

  • Since it is not wise to allow thousands of amperes to flow near sensitive electronics equipment As Zipse points out, CTS offer an entirely different approach than either of above technologies. The approach is essentially the complete opposite. Rather than encouraging the attraction between streamer and leader, a CTS discourages it, thus preventing the formation of lightning strikes in the protected area as opposed to collecting them.
  • CTS is the best option for facilities where a single spark could be catastrophic ,for example, Industries such as oil and gas, midstream storage tank farms, and energy producers of all types. These facilities often have many flammables and other sensitive materials where using a collector carries the risk of ignition or damage to electronic systems.
  • Most lightning elimination systems were originally designed for tall communication towers, but recently they have been applied to a wide range of systems and facilities including electrical substations, power lines, and airports.






3- Notes on different Types of Lightning Protection Systems LPS

Each system’s design requires the following:

  1. The air terminal or strike termination device must be positioned so that it is the highest point on the structure.
  2. The lightning protection system must be solidly and permanently grounded. Poor or high resistance connections to ground are the leading cause of lightning system failure for each one of these systems.
  3. None of these systems claims to protect against 100% of the possibility of a lightning stroke arriving near protective area. A compromise must be made between protection and economics.
  4. All Types of LPS operate off of the same scientific principal or phenomenon, known as “Point Discharge.” However, their actions diverge; the rod and ESE move toward streamer generation whereas the CTS utilize a slow discharge process.


Understanding the differences between these technologies is important. For example, it might not be ideal to collect lightning in areas that are highly volatile or indispensable, but instead to prevent it from striking altogether in these areas that are most important to protect. While lightning rods and ESE collect lightning, CTS prevents it from terminating in the area of protection.





4- Principle of Operation for Active Prevention/Elimination LPS


There are two theories as to how preventative power occurs as follows:

  1. The Bleed Off Theory,
  2. The Corona Cloud Theory.


1-  The Bleed Off Theory:

  • A multiple-point system is able to completely isolate facilities from a direct lightning strike by bleeding off the induced charge in the protected area during the course of a thunderstorm, reducing it to a much lower level in relationship to the surrounding environment, reducing the difference in potential between earth and cloud.
  • When the naturally occurring electric field in a protected area is reduced, the upward streamers are suppressed and do not get enough energy from a storm to connect with downward leaders—thus, no lightning. This in turn eliminates the secondary effects of the lightning event and helps to mitigate the immediate loss of electronics and reduction in the mean-time-before-failure of all electronics.


2- The Corona Cloud Theory:



Fig.1: Point Corona Discharge 


The sharp points on the prevention devices form a corona cloud above them (See Fig.1) that makes the device an unattractive path to the lightning stroke. The charge released via corona discharge at the sharp points will either:

A- Discharge the overhead thundercloud, thereby eliminating any possibility of lightning:

  • To prevent a lightning strike to a given area, a system must be able to reduce the potential between the site and the storm cloud cell, so that the potential is not high enough for a stroke to terminate within the area. That is, the protective system must release, or leak off, the charge induced in the area of concern to a level where a lightning stroke is impractical. (Charge induction comes about because of the strong electric field created by the storm and the insulating quality of the intervening air space.)
  • Atmospheric scientists have found that much of the storm’s energy is dissipated through what is called natural dissipation, which is ionization produced by trees, grass, fences and other similar natural or man-made pointed objects that are earthbound and exposed to the electrostatic field created by a storm cell. For example, a storm cell over the ocean will produce more lightning than the same cell over land, because the natural dissipation of the land will reduce the storm’s energy. Consequently, a multipoint ionizer is simply a more effective dissipation device, duplicating nature more efficiently.
  • The point discharge phenomenon was identified over one hundred years ago. It was found that a sharp point immersed in an electrostatic field where the potential was elevated above 10,000 volts would transfer a charge by ionizing the adjacent air molecules. (see Fig.2).



Fig.2: Point Discharge Phenomenon


B- Discourage a downward-moving leader from attaching to the device and to the structure to be protected by reducing the electric field near the device and, hence, suppress the initiation of an upward-connecting leader:


Fig.3: Space Charge Phenomenon 

  • A second phenomenon is the presence of a “space charge”. This charge develops between the protected site and the storm cell and forms what may be considered a (Faraday) shield. The ionized air molecules formed by point discharge are drawn above the ionizer where they slow down and tend to form a cloud of ionized air molecules (see Fig.3).
  • Fig.4  superimposes this situation onto an ionizer protected tower site wherein one branch is approaching the ionizer. The ionizer responds by increasing the space charge density.


Fig.4


Fig.5

  • Fig.5  illustrates the reactive space charge created by the approaching lightning leader branch. The resulting dense space charge suppresses the launch of a counter leader and the situation progresses to that illustrated by first Fig.6  and then Fig.7.


Fig.6


Fig.7

  • One branch has now terminated on a tree, all of the other streamers are withdrawn; and finally, the ionizer created space charge is also withdrawn through the Ionizer creating a reverse discharge current flow, lasting only a few microseconds. All of those charges that are in the branches and around the ionizer take part in the neutralization function as illustrated by Fig.7. The earth returns to the normal negative state when the storm cells are discharged or not present.







5- Types Of Lightning Elimination/Prevention Systems

There are two basic types of lightning elimination/prevention systems in the market, which are:

  1. Dissipation Array System (DAS),
  2. Charge Transfer System (CTS).



1- Dissipation Array System (DAS):


Dissipation Array System

  • Hughes states that a patent for a multiple-point system was issued in 1930 to J. M. Cage of Los Angeles, California. The patent describes the use of point-bearing wires suspended from a steel tower to protect petroleum storage tanks from lightning.
  • A similar system, commonly referred to as a dissipation array system (DAS) has been commercially available since 1973 although the product name and the name of the company that marketed it have changed over time.
  • Although DAS Systems are available in varying shapes and sizes, the DAS system typically consists of a hemisphere of a large radius with an array of many thin metal splines with sharpened tips distributed evenly over the hemisphere's surface
  •  
  • The concept of corona space charge is specifically important to the operation of the DAS. DAS is based on a natural phenomenon known to scientists for centuries as the “point discharge” principle or charge transfer. A sharp point in a strong electrostatic field will leak off electrons by ionizing the adjacent air molecules, providing the point's potential is raised 10,000 volts above that of its surroundings.
  • The DAS employs the point discharge principle by providing thousands of points with specific point separation, which simultaneously produce ions over a large area.
  • Due to the corona space charge created by DAS, the formation of counter leaders are delayed prevented long enough to allow other branches of a downward leader to terminate on some other unprotected ground object. As the study demonstrates, after the contact between the downward leader and ground, the lightning channel is neutralized and the object protected with DAS remains undamaged.
  • Since taller structures are more prone to collecting a strike, the primary location for DAS to be distributed is on the tallest structures. Anything within the area of these taller structures will be protected since they are in the zone of protection of the DAS.


Factors Affecting The Design Of Dissipation Array System (DAS):

The proper design of a DAS for protection of a given area or structure is based on several factors. The major considerations include:

  1. Severe thunderstorm parameters,
  2. The configuration of the structure,
  3. Local environmental conditions,
  4. Structure construction methods,
  5. Vulnerability of electrical and electronic systems,
  6. The physical strength of the structure.


All of these are taken into account in determining the best method to protect the structure.


Benefits of using Dissipation Array System (DAS):

  1. DAS is simple (the design is straightforward, reliable and effective),
  2. DAS is passive (it consumes no power; it is activated by the energy of the storm itself)
  3. DAS is universal (DAS can be used to protect any kind of building, tower, power line or large complex plant).
  4. DAS is flexible (Basic system concepts are custom engineered for each individual facility and specially designed to account for size, height, area storm patterns and altitude)
  5. The DAS is preventative (it completely eliminates lightning strikes and all related secondary effects from the protected area and avoids problems inherent in lightning rod systems, which attract energy and attempt to conduct it to ground)
  6. DAS is guaranteed effective (if a strike does penetrate the DAS-protected area, most manufacturers will upgrade the system capability at no additional cost to the user for one year from the date of installation and/or recertification).


2- Charge Transfer System (CTS):




Due to the adverse publicity on the DAS terminology, the inventor had introduced a new concept to describe his invention in the 1990s and named it as the Charge Transfer System (CTS), and this means that CTS is the Generic name of DAS.


Note: 

In this course we separate the two terms DAS and CTS to help you in differentiating between them, but as we stated above, the two terms are related for the same product technology.




In the next Article, I will continue explaining the Non-Conventional Lightning Protection System. Please, keep following.



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