lightning, surge protection and earthing of electrical and electronic systems in industrial networks
DESCRIPTION
Few topics generate as much controversy and argument as that of lightning and surge protection of electrical and electronic systems. Poor practices in earthing, and incorrect application and selection of lightning and surge protection devices can be the cause of continual and intermittent problems in a facility, often resulting in lost production and equipment failure. This workshop looks at these issues from a fresh yet practical perspective and enables you to reduce expensive down time on your plant and equipment by the correct application of these principles. Essentially the workshop is broken down into the methods used to prevent lightning entering a facility such as dissipation arrays and those that divert surge energy away from sensitive equipment. Dissipation systems are discussed with associated earthing systems. The unique properties of various surge protection devices are reviewed, enabling you to select the correct device suited to the application required. Earthing and surge protection for telecommunications and IT systems are examined in detail as well as the impact of lightning and simple techniques for minimising its impact. MORE INFORMATION - http://www.idc-online.com/content/lightning-surge-protection-earthing-electrical-electronic-systems-industrial-networks-13?id=6987TRANSCRIPT
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Lightning, Surge Protection and Earthing of Electrical and Electronic Systems in Industrial Networks
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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
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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
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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
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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
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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.
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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)
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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
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WORLDWIDE LIGHTNING ACTIVITY
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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
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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)
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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.
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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
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MAINTENANCE
• Lightning protection system components are exposed to weather for extended periods
• They require periodic inspection and maintenance just like any other electrical system
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DO YOU WANT TO KNOW MORE?
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