What does a lightning protection system do?
The basic functionality of a lightning protection system is to protect structures from fire or mechanical destruction and persons in the buildings from injury or even death which could be caused due to lightning activities.
What are the major parts of a lightning protection system?
A lightning protection system can be divided into two sub systems, external and internal.
External lightning protection system consist the following:
- An air-termination system to intercept direct lightning strikes via
- A down-conductor system to safely conduct the lightning current to the ground
- An earth-termination system to distribute the lightning current in the ground
Internal lightning protection system consist the following:
- Equipotential bonding or maintaining a separation distance between the components of the lightning protection system and other electrically conductive elements inside the structure to prevent dangerous sparking inside the structure.
- Surge protective devices, to protect equipment from dangerous over voltage spikes
What are the solutions available for direct lightning protection?
Air-termination systems for direct lightning protection can consist of the following components which could be present as a combination of following as well:
- Rods
- Spanned wires and cables
- Meshed conductors
With new developments ESE (Early Streamer Emission) lightning protection for direct lightning has come to play, these rods are referred to as active lightning rods, which come with different protection radii. Power Net Engineering Pvt Ltd specializes in this type of direct lightning protection systems. Shown bellow are some ESE type lightning rods and the typical protection area.
What does ESE type direct lightning protection system consist?
There are mainly three parts for the direct lightning protection system:
- The ESE lightning rod to intercept direct lightning strikes
- A down-conductor preferably copper or aluminum tape
- A test clamp for testing the earth conductivity
- An earth-termination system, copper plate or copper bonded earth rods, the down conductor will be welded to the earthing system.
How to ensure earth conductivity of the earth termination system?
The earth termination system must be inspected annually to ensure proper conductivity and it should not exceed 10 Ω.
How lightning surges are generated?
- Direct Lightning Strike
- Striking of external lightning protection system, structure
- Voltage drop at impulse earthing resistance
- Induced voltages in loops
- Distant Lightning Strike
- Strike into overhead lines
- Surge induced due to cloud to cloud lightning
- Inductive load switching
How the correct SPD is selected?
SPDs are based on the location that needs protection and the equipment that needs to be protected. There are several types of protection in SPDs
Type 1: Permanently connected, intended for installation between the secondary of the service transformer and the line side of the service disconnect overcurrent device (service equipment). Their main purpose is to protect insulation levels of the electrical system against external surges caused by lightning or utility capacitor bank switching.
Type 2: Permanently connected, intended for installation on the load side of the service disconnect overcurrent device (service equipment), including brand panel locations. Their main purpose is to protect the sensitive electronics and microprocessor-based loads against residual lightning energy, motor generated surges and other internally generated surge events.
Type 3: Point-of-utilization SPDs installed at a minimum conductor length of 10 meters (30 feet) from the electrical service panel to the point-of-utilization. Examples include cord connected, direct plug-in and receptacle type SPD
What can be protected by SPDs?
SPDs are available in a wide range to select, from power systems to telecommunication. Shown below are some of the available SPDs for different applications
1 – SPD used for electrical panels
2 – SPD used for networks, RJ45 (RJ11 is also available)
3 – SPD used at socket outlet level
4 – SPD used for ELV systems
5 – A spark gap type SPD
6 – SPD used RS-485, RS-232 connectivity applications
Does the protection of a well-designed lightning protection system is 100% guaranteed?
Short answer is No. Since lightning is a natural phenomenon, its behavior is not predictable, however a well-designed lightning protection system will minimize the probability of structures or other equipment being damaged due to lightning.