What is a Lightning Arrester? : Working Principle, Types and Differences

Hello guys, welcome to the new post. In this post, we will learn what a lightning ester is. Lightning striking at the time of storms can be dangerous to circuits and human beings. The voltage-current surge can cause high damage and also electric fire. To reduce that risk, lightning arrestors are used. Different types of arresters are used, such as class 1 arresters, which dissipate more current than class 2 arresters. In this post, we will discuss the detailed parameters of lightning arresters, their working principle, and the different types. Let’s get started with what a lightning arrester is.

What is a Lightning Arrester?

The lightning arrestor, known as a lightning isolator, comes with an air gap between the electrical wire and ground used on electrical power transmission and telecommunication systems for protection insulation and conductors of a system through the effect of lightning.

The lightning arrester comes with a high-voltage terminal and ground terminal. If lightning surges move with the power line to the arrester, the current from the surge is diverted through the arrester and, in some conditions, to earth.

In telephony and telegraphy, lightning arresters are configured where wires add a structure, saving damage to electronic instruments and making sure the safety of components is connected.

Small types of lightning arresters, also known as surge arresters, are devices that are connected between conductors in power and communication and earth.

Working Principle of Lightning Arresters

The lightning arrester does not save lightning from striking homes or buildings. It is connected between power lines and homes, substations, or breakers.

Lightning rods are different from arresters in such a way that they are passive rods that absorb lightning strikes and send them through a connected cable with the ground.

The electrical circuits operate at risk of being affected by a sudden surge in power when using a lightning rod. The lightning arrester comes with a high-voltage terminal and a ground terminal.

The current spike naturally needed to flow to electrical components. It is where the lightning arrester performs. It diverts extra current in a predetermined location.

Types of Lightning Arresters

Rod Type Lightning Arrester

It is a simple type of arrester. In this arrester, there is an air gap between the ends of two rods. One end of the arrester is connected to the line, and the second end of the rod is connected to the ground.

The gap setting of the arrester must be such that it breaks before the damage. If high voltage exists on line, gap sparks and fault current to earth. So devices connected are protected from damage.

Sphere Gap Arrester

In this type of arrester, the air gap is given between different spheres. On the spheres is connected with a line, and the other sphere is connected with the ground.

The spacing between the two spheres is small. The choking coil is inserted between the phase winding of the transformer, and the sphere is connected with the line.

The air gap between the arrester is configured in such a way that discharge does not occur at normal operating conditions. The arc passes through the sphere when heated air closes the arc, causing a rise in the upward direction and lightning till it is interrupted automatically.

Multiple-Gap Arrester

The multiple gap arresters come with a series of small metallic cylinders insulated from each other and parted through air gaps. The first and last of the series is connected to the ground. The number of gaps needed is based on line voltage.

Lightning Arrester in Substation

Lightning arresters used in substations are larger-sized devices that come with porcelain tubes of longer feet and some inches in diameter, normally filled with discs of zinc oxide. The safety port on the side of the device’s vents’ inner explosion occurs occasionally without shattering the porcelain cylinder.

Lightning arresters prevent lightning damage to devices connected due to high voltage. The lightning arrester offers a low-impedance road to the ground for lightning current. It restores to normal working conditions.

Features of a Surge (Lightning) Arrester

• The accurate working lightning arrestors quickly break down when faced with an abnormal voltage for the rated breakdown value. The breakdown means the function of the lightning arrester, where the insulation breaker is for some time, so the voltage surface goes to the ground.
• It must divert current at an accurate time that transient voltage creates a breakdown threshold.
• Spart overvoltage must be over the normal frequency existing in the system for the device to operate. It does not work for normal conditions.
• Lightning arrestors must discharge electrical energy without losing durability.

How a Lightning Arrester Works

A lightning arrester avoids lightning damage to devices due to high voltage. The lightning arresters offer a low-impedance path to the ground for lightning current.

After that, it restores normal conditions. The lightning arrester is like the relief valve of the water heater. It releases high pressure until it works in normal conditions.

If pressure is at normal value, then the safety valve is ready to move next. If high voltage is on the line, a lightning arrester opens a path for ground in the result limit and drains the high voltage.

Lightning arresters perform two functions.

1. Make a point in the circuit where the overvoltage pulse can move to the ground.
2. It prevents follow-up voltage current from moving to the ground.

Differences Between Types of Lightning Arresters

Electrolytic arrester

• Plates work as high resistors to low voltage values. A voltage of more than 400 volts affects impedance so fault current passes to the ground.

Rod Gap Arrester

• It is a simple lightning arrester. It has a gap between the ends of two rods. These two rods get connected with the earth and line directly.

Valve-type lightning arrester

• It has divided the spark gap in series with the resistance component having nonlinear features. Divided spark gaps have the same component connected in series. Everyone has two electrodes with a pre-ionization device.

Metal-Oxide Lightning Arrester

• It is a semiconductor N-type material. material is doped with adding some high-power insulating oxides. The powder is treated with some process and then compressed into a disc shape. The disc is enclosed in porcelain housing filled with nitrogen gas or SF6.

Oxide Film Arrester

• The oxide film arrester is a new lightning arrester created with the use of a film of insulation in contact with conducting powder.

Sphere Gap Arrester

• It has a choosing coil between the transformer and the ground that is heated when the voltage increases. Air between spheres heated up and released. But corona discharge ionizes air, and fault current passes through it. So it saves damage to the device.

Horn-Gap Arrester

• It has two horns that share metallic pieces separated by a small air gap and connected in a shunt between the conductor and the earth. The distance between two electrodes is such that the normal voltage between the line and the earth is not enough to cross the gap.

Multiple Gap Arrester

• It comes with a series of small metallic cylinders insulated from each other and separated by an air gap. The first and last of the series is connected with the ground. Number of gaps needed based on line voltage.

Thyrite Lightning Arrester

• It is used for very high-voltage conditions. It comes with a ceramic material called thyrite, which has variable resistance. The resistance is inversely proportional to the voltage at the ends of it.

Autovalve Arrester

• Autovalve arresters come with an arc gap pile comprising a series of arc gaps configured in series with a resistance. This resistance is made of a material varying its resistance when the voltage changes.

Characteristics of an Ideal Lightning Arrester

1. It does not draw current in the normal operation.
2. Any voltage that is not normal over the breakdown value should result in breaking within some seconds. So it can provide a conductive path for current to go to ground.
3. In case of a high surge, it can carry discharge current without any damage.
4. The power frequency current of breakdown interrupted fastly transient voltage is less than the breakdown value.

Location of Lightning Arrester

The lightning arrester is connected close to a device that needs protection. It is normally installed between the phase ground in the AC system and the pole and ground for the DC system.

In the AC system, separate arresters are used for each phase.

For very high-voltage AC systems, the surge diverter is used to protect generators, bus bars, transformers, line breakers, etc. For HVDC system arresters used for protection, buses, valves, converter units, and filters

Read Also: transformers and circuit breakers..

Lightning Arrester vs Surge Arrester