Lightning is one of the most powerful forces of nature and lightning strikes can cause a lot of damage. When lightning strikes, it creates a high voltage discharge that emanates from the cloud in the form of lightning bolts. These lightning bolts can reach as far as 10 miles to strike something on the ground, which is why anything standing tall or with a point at its top is prone to get hit by these lightning bolts.
To protect buildings, transmission towers, and other structures against lightning strikes, special devices are used called lightning arresters. Let’s take a look at everything you need to know about lightning arresters.
What Is Lightning Arrester?
A lightning arrester is a device that is used to protect structures against lightning damage. It is installed at the top of the structure above the rooftop or somewhere in the vicinity and connected to the structure using proper wiring.
How Does Lightning Arrester Work?
A lightning arrester is a device used to protect against lightning strikes. It is connected to a structure with a wire that has an electrical ground at one end. If a lightning bolt strikes nearby, it will become charged with high voltage and create an electric discharge through the air towards the ground.
The electrical ground leading to the structure is connected to the ground, so it gets charged as well. The high voltage of the charge needs to be discharged to the ground too.
However, if the structure is made of an electrical conductor, it will get charged as well, leading to serious damage.
This is where the lightning arrester comes into play. It is designed to get charged with high voltage without getting damaged.
Instead, it diverts the flow of charge to the ground through a different path. Thus, it protects the structure from the harmful effects of a lightning strike.
Main Components of a lightning arrestor
– Lightning Arrestor – This is the main component of a lightning arrester, which is designed to withstand the high voltage charge and get hot as it discharges the charge to the ground through a different path.
– Air Terminals – Air terminals are located at the top of the lightning arrester. They are made of a conductive material and are pointed towards the sky to attract lightning.
– Earthing Terminals – Earthing terminals are the electrical ground terminals of the lightning arrester and they get connected to an electrical ground. – Arresting Switch
– An arresting switch is a type of lightning arrester that gets closed when lightning strikes nearby. It allows the high voltage charge to flow through it and get discharged to the ground.
Types of Lightning Arrester
It is important to know that not all the lighting arrestors in the market are the same. They come in different variants and have different features. Let’s look at some of the most common types of lightning arrestors that you should know:
Station class lightning arrestor
This type of lightning arrestor is mainly used at power stations and other high-voltage installations. It is built to withstand high voltage and has a high breaking capacity.
This lighting arrestor is designed to protect equipment that is rated over 20mVA.
Intermediate class lightning arrestor
This type of lightning arrester is used in places where the voltage range between 20mV and 1000mV. It is mainly used in telecom towers and substations.
Low-voltage class lightning arrestor
This variant of lightning arrestors are used to protect low-voltage equipment such as computer systems, data centers, telecommunication equipment, etc. They are designed to protect electronics from the dangerous surges generated by lightning.
Lightning arrestors for cables
Lightning arrestors for cables are designed to protect cables from lightning strikes. They are usually installed at the entrance or exit point of a cable system that is exposed to a high risk of getting struck by lightning. They provide protection against direct strikes on cables and indirect strikes from nearby objects such as buildings, trees.
Distribution class lightning arrestor
This type of lightning arrestor is usually used on equipment that are rated over 1000KVA. The arrestor can either be a dry type or liquid-filled and is directly connected to the rotating components.
Horn gap lightning arrestor
As the name suggests, the arrestor has two rods that are separated by a gap forming a horn-like structure. The horn gap arrestor is a type of lightning arrester that uses a gap in the form of a horn to dissipate dangerous electrical charges.
Ceramic insulators are used for supporting the metal rods. It is used on large power systems and is highly effective at protecting against indirect strikes.
The multi-gap arrestor is a device that consists of multiple gaps that are used for dissipating lightning strike energy more effectively. It also has several metal cylinders which are separated from each other by the said gaps.
The arrestors are generally cylindrical in shape and are made of copper or aluminum.
Some of these gaps have shunt resistance whose primary task is to absorb the surge current.
Valve-type lightning arrestor
The valve-type lightning arrestor is a device that is used for protecting the power systems from direct strikes. It consists of a metal tube that has one or more metal plates inside it. The plates are separated by a gap, which is designed in such a way that it can dissipate the lightning strike energy.
In pipeline arrestors, lightning protection is done by placing the arrestor within the pipeline itself. This arrestor consists of a metal pipe inserted into the pipeline through an opening on its side. This opening allows for the passage of electrical current to and from the ground.
Metal oxide lightning arrestor
This lightning arrestor has a zinc oxide which is its primary resistor. It is a non-metallic material that has a high dielectric constant and thus can be used to absorb the lightning strike energy. This arrestor is also called “ZnO” or “ZnO-based lightning arrestor”.
Metal oxide arrestors are generally used in power transmission lines and substations, but they can also be found in some consumer appliances like televisions, computer monitors, and other small devices.
Electrolyte lightning arrestor
This lightning arrestor is composed of a glass tube filled with liquid electrolyte. When the lightning strike occurs, the electrolyte changes state from an electrical insulator to an electrical conductor. This change in conductivity allows for the flow of electric current through the arrestor and down to ground.
The electrolyte used in this device is generally a high-temperature salt solution (e.g., molten salt), which can be cooled by using cold water or ice water as a coolant to prevent excessive temperature rise when the device is being used.
What to Look for When Buying a Lightning Arrester?
– Make sure the lightning arrester is rated appropriately for the structure you want to protect and the distance between it and the lightning strike. – Choose a lightning arrester that has an Arresting Capacity of at least 100 kA and has a color code of either purple or red.
– It is important to check if the lightning arrester has an Arresting Capacity of at least 100 kA. An arrester with a lower arresting capacity may get closed due to high voltage and fail to protect the structure.
– Always choose a lightning arrester that has been listed and approved by an independent agency like Underwriters Laboratories (UL), Canadian Standards Association (CSA), or National Lightning Protection Standard (NLPW).
-Check the build quality: Ensure that the lightning arrestor exhibits signs of quality build. Its material should be durable and the overall design should be sturdy.
Where to install a lightning arrestor
The best place to install a lightning arrester is at the highest point of the structure.
However, it is not always possible to install it on the rooftop. In such cases, you can install it in the attic, on the side wall of the structure, or on a pole.
However, make sure to keep the distance between the lightning arrestor and the ground as close as possible so that the charge can flow easily to the ground.
If the lightning arrester is installed in the attic, it is important to make sure that the attic is well insulated so that the high voltage charge does not get diverted to the insulation. This can cause damage to the insulation and surrounding items.
Reasons to install lighting arrestor
The main reason for installing a lightning arrestor is to prevent damage caused by lightning strikes.
The ability to divert charge from the high voltage wire to the ground is the main function of a lightning arrestor.
The other functions include preventing damage to the electrical system and preventing excessive heat generation caused by electrical discharge.
Lightning arrestors can also prevent electricity from flowing into the air, which can cause fire or explosion due to the high voltage charge traveling through the air.
Other than property damage, lightning arrestors are also installed to save lives. Most public buildings such as schools, churches, hospitals, airports, and other buildings are required by law to have lightning arrestors installed to prevent the massive loss of life that can take place due to the incidences of lightning.
Precautions to follow when installing lightning arrestor
– Make sure the wires leading from the lightning arrestor to the structure are not exposed to weather or are not crossing each other. This can cause a short circuit and damage the lightning arrester.
– Make sure the lightning arrestor is properly grounded so that it can discharge the excess voltage to the ground.
– Never touch the lightning arrestor during a lightning storm. This can lead to serious injury due to the high voltage.
– Never try to open the lightning arrestor during a lightning storm. This can lead to serious injury due to the high voltage.
– The lightning arrestor should be inspected by a certified electrician once every year.
-Hire an expert to do the installation. If you are not familiar with the details regarding lightning arrestor installation, it will be better to hire an expert to do the job for you.
Lightning arrestor vs Surge arrestor: What is the difference?
Most people tend to assume that lightning arrestors and surge protectors are the same devices. In reality, the two are completely different. Let’s look at some of the key features that separate the two.
-Installation: Lightning arrestor installation can be implemented outside the panel board. On the other hand, surge arrestor installation must be done inside the panel board.
-Function: The main function of a lightning arrestor is to protect the electrical system from lightning strikes. The main function of a surge protector is to protect the electrical system against surges and spikes.
-Functional difference: Lightning arrestors are a type of surge protector, but not all surge protectors are lightning arrestors.
-Protection level: Lightning arrestors offer a protection level that’s just one step below that of a lightning rod, which is considered to be the highest protection level in this field. On the other hand, surge protectors offer protection only against surges and spikes.
-Type: Lightning arrestors can be installed both indoors and outdoors while surge arrestors can only be installed indoors.
Why do lightning arrestors fail?
A lightning arrestor can fail due to the following reasons:
-Shorted connection: Lightning arrestors are often connected to a lightning ground through a copper clamp or other means. If the copper clamp or other part of the connection is damaged, the lightning arrestor can fail.
-Insulation failure: Lightning arrestors are usually made of rubber. Since rubber has a low resistance, it’s not enough to protect against lightning strikes. As time goes by, the rubber inside the lightning arrestor will deteriorate and deteriorate more until it eventually fails.
-Air gap loss: When lightning strikes an object, it creates a plasma ball that can travel up to several meters away from the point of impact. During this process, there will be what is known as an air gap between the object and the ground that can be as large as several meters depending on where the strike occurred.
-Dangerous current flow: Lightning arrestors have very high resistance levels so they’re able to withstand high current flows without suffering any damage while surge protectors have very low resistance levels.
-Poor connection: Most lightning arrestors are connected to their grounding system using copper clamps. If a lightning strike occurs, the copper clamp might be damaged or the
connection to the grounding system might be faulty.
I hope you now know what lightning arrestors are, what they do, and why you need one. I also hope that you now know how to choose the right lightning arrestor for your needs.
The choice of which lightning arrestor to purchase is a very important one as it affects the safety of your equipment. You should always take the time to research your options before making a decision.
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