The main and most effective measure for protection of structures against physical damage is considered to be the lightning protection system (LPS). An External LPS provides protection against physical damage and life hazards whereas internal LPS provide protection for electrical and electronic systems. In this article, we shall explore about the overview of Internal and External lightning protection system as specified in IS/IEC 62305 standard.
External Lightning Protection System will protect the buildings/structures from physical damages due to direct lightning strikes. An external Lightning Protection System consists of,
The function of the internal LPS is to prevent dangerous sparking within the structure using equipotential bonding or a separation distance. Internal Lightning Protection System will provide protection to the electrical and electronic equipments inside the structure from the lightning impulse surges.
The main causes of transient over voltages are,
Among these, lightning is the natural source of impulse surges. IS/IEC62305 classifies the sources of damages due to lightning strikes into 4 groups and they are as follows.
Damages due to lightning strikes on the structure shall be protected by using External Lightning Protection system whereas the electrical equipments shall be protected from lightning impulse currents by using Surge Protection Modules in combination with good earthing system.
Lightning impulses are silent killer of electronic devices inside the structures. The failure of internal systems due to lightning surges are caused by,
The protection measures for any Lightning Protection Zone (LPZ) shall comply with IEC 62305-4.
Protection measures such as LPS, shielding wires, magnetic shields and SPD determine the Lightning Protection Zones (LPZ). The protection zones as specified by IS/IEC 62305 are as follows.