The main and most effective measure for protection of structures against physical damage is considered to be the lightning protection system (LPS). IEC 62305 explains about the Internal and External lightning protection system.
Internal Lightning Protection System will provide protection to the electrical and electronic equipment inside the structure from the lightning impulse surges.
The Surge Protection Devices (SPD) is a generic name for any device to protect from voltage surges and an effective solution for the overvoltage problem. They are designed to be incorporated in an installation to protect all electric, electronic, and data-processing equipment from transient over voltages.
Surge Protection Devices (or SPDs) are units combining several protection components like Metal Oxide Varistor, spark gaps, gas discharge tubes, thermal protection fuse and indicators to protect the electrical and electronic devices from voltage surges. They divert the transient surges to the ground thereby protecting the equipments.
The problems due to surges were present from the earlier days but it was not taken into consideration because of the lesser sensitivity of the loads which were used earlier. Because of the technical advancements in electronic industry, we are gradually migrating towards the automation of processes in industries. For the monitoring and control, we use electronic devices which were very sensitive to transient surges and electromagnetic disturbances.
The higher sensitivity of the electronic devices towards these transient surges due to lightning and switching impulses emphasis the need for surge protection devices.
The damages due to surges may not be immediate. The effects on the electrical devices due to surges are mainly classified into three types as,
The effect of surges with lower magnitude may not be felt at the time of encounter but it will slowly affect the life time of product which leads to premature ageing of the electronic devices. Hence these surges are considered as the silent killers of electronic equipment.
An example of SPD module installation arrangement is shown below.
SPD in combination with good grounding system shall be used to protect the electrical and electronic equipment from these surges.
Provision of Surge Protection device in total will improve the,