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Lightning, Surge Protection and Earthing of Electrical and Electronic Systems in Industrial Networks


LEARNING OBJECTIVES– Surge and its effects– Lightning and its dangers– Basics of Lightning protection– Codes relating to Lightning protection– Lightning Protection of a structure

– Worldwide Lightning activity

– Lightning detection and warning

– Role of grounding

– What is Bonding?

– Basics of surge protection Lightning protection system maintenance

– Worldwide Lightning activity

– Lightning detection and warning

– Role of grounding

– What is Bonding?

– Basics of surge protection Lightning protection system maintenance


WHAT IS A SURGE?

• A steep transient rise of voltage of very short duration (mS or even S) in an electrical system

• External Reason - Lightning

• Internal Reason - Switching of Reactors or Capacitors


EFFECTS OF SURGE• Voltage Stress on electrical insulation

• May lead to insulation failure

• May generate excessive heat due to high currents of lightning discharge

• May cause failure of sensitive components due to high currents or high induced/transferred potential


LIGHTNING DANGERS

Lightning is the sudden discharge of built up charge in a cloud system.

• Effects of surges are limited to electrical circuits

BUT

• Lightning can affect electrical circuits, living beings and structures.

• It can cause high potential differences in soil and between different parts of a building

• It can cause death due to high currents


PROTECTION REQUIREMENTS

• Lightning Protection systems as per relevant codes

• Quality Grounding / Earthing grid / Bonding

• Surge arrestors in Power circuits

• Multi-Level graded protection of signal paths using Surge Protective Devices (SPD)

• Periodic Maintenance of Systems to ensure integrity of conducting paths.


LIGHTNING PROTECTION CODES

• AS 1768 (INT) 2003: Australian Standard on Lightning protection

• ANSI/NFPA 780: National Lightning protection code

• IEC 61024: Protection of structures against lightning

• IEC 61662: Assessment of risk due to lightning

• IEEE 142-1991: IEEE Green Book (Chapter-3)


PROTECTION OF BUILDINGS

• Decided based on perceived Risk

• Related to thunderstorm activity in the area concerned

• Isokeraunic maps for different regions

• Other features such as type, use, location, terrain etc.

• Protection by Franklin Rod (lightning mast)

• Protection by Faraday Cage (Mesh protection)

• Assessment of protection-By Cone of protection, RSM and CVM techniques

• Non-conventional protection methods


WORLDWIDE LIGHTNING ACTIVITY


DETECTION AND WARNING

Objectives:– Detection to measure lightning activity

– Detection to warn of imminent thunderstorms

Methods:– Detection by using a network of sensors for a large geographic area

– Detection by using standalone sensors for a specific area


ROLE OF GROUNDING

• Provides a low impedance path to the flow of lightning discharge currents

• Limits the ground potential rise

• Limits ground resistance to be as low as possible (< 10 Ohms)


ROLE OF BONDING

– Potential differences between simultaneously accessible metal surfaces to be limited

– Bonding both above and below ground

– All metallic piping below the ground to be bonded to Lightning protection system.


SURGE PROTECTION

– Surge can be transmitted into circuits through:• Galvanic (Direct Electrical Contact) contact• Electrostatic coupling• Electromagnetic Induction• Radio Frequency interference (RFI)

– Severity reduces along path of power flow

– Graded protection depending on the location of circuit.

– Use of TVSS and SPD


MAINTENANCE

• Lightning protection system components are exposed to weather for extended periods

• They require periodic inspection and maintenance just like any other electrical system


DO YOU WANT TO KNOW MORE?

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Download - Lightning, Surge Protection and Earthing of Electrical and Electronic Systems in Industrial Networks

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