Lightning is the process of discharging the electrical charge in a cloud. Lightning energy released can produce a series of light, heat, and a very strong sound, it can damage buildings, kill humans, blow up trees and impair electrical equipment. The average speed of lightning is 150,000 km/sec and it usually arrives with a jarring sound.

The process of the lightning occurring is due to differences in electrical charges between the clouds with the earth or between other clouds. As the electrical charge in the cloud moves continuously and on a regular basis, during its movement it will interact with other clouds so that the negative charge will congregate on one side (top or bottom), while the positive charge is assembled on the opposite side.

In the event of such a large potential difference between the cloud and the earth, as well as clouds with clouds, there will be a discharging of electricity from cloud to earth or vice versa to achieve the balance of electrical charge (discharge).

In accordance with IEC 61024-1 standards concerning protection against lightning strikes and IEC 1312 on protection against electromagnetic impulses, the general concept of a lightning protection system according to IEC 1024 – 1 and IEC 1312 standards is as follows.

A functional protection system consists of 2 parts:

1. External Protection System
2. Internal Protection System

External Protection System

External protection systems are tools installed on the outside of the building which serve to protect buildings and people against direct lightning strikes.

3 parts of an External Protection System:

1. Finial (air terminal/copper tapered rod) mounted at the top of the building which serves to catch the lightning strike directly.
2. Down Conductor (minimal conductor cable BC 50 mm2) mounted on the outer wall of the building which serves to distribute the flow of electrical charges from the finial to grounding.
3. Grounding of copper installed in the ground serves to discharge an electrical charge from the conductor cable to the copper rod embedded in the ground. All grounding should be connected directly, or Spark Gap can be used. The smaller the grounding value is, the more quickly the discharge of electric charge from lightning to the ground will be absorbed into the ground (maximum grounding value = 1 Ohm)

Internal Protection System

Internal protection system is a device installed on the inside of a building which serves to protect electrical equipment (electronics) against lightning induction (a momentary but large spike in voltage)

Internal protection system consists of 2 parts, namely:

1. Equipotential Bonding (EB) is the connecting of all metal/grounding cables to the internal copper plate (PEB = Potential Equalizing Bar), which is to be connected to the main grounding outside the building. This is useful for removing the potential difference in the equipment when they are exposed to lightning induction.
2. Installation of Arrester in Main Distribution Panel (MDP) with Arrester type Over Current, Sub Distribution Panel (SDP) with Arrester type Over Voltage and in equipment with Arrester type Fine Protector

Lightning protection zone concept

The lightning protection zone concept described in international standard IEC 62305-4 has proved to be practical and efficient. This concept is based on the principle of gradually reducing surges to a safe level before they reach the terminal device and cause damage. In order to achieve this situation, a building’s entire energy network is split into lightning protection zones (LPZ = Lightning Protection Zone). Installed at each transition from one zone to another is a surge arrestor for equipotential bonding. These arrestors correspond to the requirement class in question.

Lightning protection zones concept according to IEC 62305-4 (EN 62305-4)

• LPZ 0A: direct lightning strikes & high electromagnetic fields occur
• LPZ 0B: no direct strike but high electromagnetic field
• LPZ 1: without direct strike, the electromagnetic field is weak
• LPZ 2: areas with weak electromagnetic fields
• LPZ 3: protection area inside equipment

Any electrical, telecommunication, data, and other equipment undergoing a zoning change should be equipped with an arrester. 

Lightning protection zones and comprehensive protection measures

Surge protection devices are classified into lightning current arresters, surge arresters and combined arresters according to the requirements of their installation. Lightning current and combined arresters which are in LPZ 0A to 1/LPZ 0A to 2 fulfill the most stringent requirements in terms of discharge capacity. These arresters must be capable of discharging partial lightning currents of 10/350 μs wave form several times without destruction, thus preventing injection of destructive partial lightning currents into the electrical installation of a building.

Surge arresters are installed at the transition from LPZ 0 to 1 and downstream of LPZ 1 to 2 and higher. Their function is to mitigate the residual currents of the upstream protection stages and those generated in the installation.

Choosing the right surge protection devices

The classification of surge protection devices into types can be matched to different requirements with regard to location, protection level and current-carrying capacity. The table provides an overview of the zone transitions

Zone transition	Surge protection device and device type	Product example
LPZ 0 B to LPZ 1	Protection device for lightning protection equipotential bonding in accordance with VDE 0185-305 (IEC 62305) for direct or close lightning strikes. Devices: Type 1 (Class I), e.g. FLT-SEC Max. protection level according to standard: 4 kV Installation e.g. in the main panel/at building entry	FLT-SEC Item no.: 2905421
LPZ 1 to LPZ 2	Protection device for lightning protection equipotential bonding in accordance with VDE 0185-305 (IEC 62305) for direct or close lightning strikes. Devices: Type 2 (Class II), e.g. VAL-MS 230 Max. protection level according to standard: 1.5 kV Installation e.g. in the distributor panel/at building entry	VAL-MS 230 Item no.: 2838209
LPZ 2 to LPZ 3	Protection device, designed for surge protection of portable consumers at sockets and power supplies. Devices: Type 3 (Class III), e.g. MNT-1D Max. protection level according to standard: 1.5 kV Installation e.g. on the end consumer	MNT-1D Item no.: 2882200

Arrester type over current (level 1) is an arrester that serves to cut a very large lightning current (maximum 100 kA) and quickly (100 ns) directs its flow to grounding, but there is still a return voltage generated.

Installations of level 1 arresters are typically on the outer side of the power grid (before the meter PLN/parent panel or Genset)

Arrester type over current (level 2) is arrester that serves to cut over voltage (20 kA) from lightning induction and reverse voltage and even more quickly (20 ns) drain it by grounding, Metal Oxide Varistor (MOV) has the ability to cut the lightning voltage inversely with its sensitivity level.

Arrester type Fine Protector (level 3) is an arrester that serves to cut the remaining voltage from the 2nd level arrester (3 kA) and directs its flow to ground within 25 ns.

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