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Objective and scope of study:
The objectives and scope of the Lightning & Surge Protection Study are as follows:
- Review the existing lightening protection system against national and international standards and correction and addition in the system to comply with applicable standards along with risk analysis.
- Study of maintenance aspects of lightening protection and suggest suitable corrective actions in existing system.
- Risk analysis & design reports with all as build drawings (as received from client)
- Reference standards applicable for the premises.
Lightning & Surge Protection Study – Sequence
RISK ASSESSMENT & DESIGN
- Risk Assessment Calculation Considering all elements as described in the IEC 62305 Part 2.
- Structure Dimension – Collection area calculation
- Structural Attribute calculations – Wm1, Wm2 & multiple Ks factors
- Environmental Influences (Line, Location, Ng, TS days etc)
- Adjacent Structure Contribution factor derivation
- Power line factors
- Existing protection measure
- Loss of human life parameter derivation
- Selection of areas/buildings/structure/process area with higher probability >1*10e-5
- Review of existing lightning protection installed for structures & buildings of the plant.
- Selection of method for external lightning protection
As per prescribed methods in IS/IEC 62305 Part 3 selection of method shall be done as per the structure and complexity.
Acceptable methods to be used in determining the position of the air-termination system include:
- The protection angle method
- The rolling sphere method
- The mesh method
Table 2- of IEC 62305-3
Maximum value of rolling sphere, radius, mesh size and protection angle corresponding to the class of LPS
LPS definition shall freeze while on site visit and calculations done.
A typical structure shall be subjected to desired method as shown below –
Calculation for the rolling sphere or, mesh shall be shown for the structures used –
Air termination systems can be composed of any combination of the following elements:
- Rods (including free-standing masts)
- Catenary wires
- Meshed conductor
- Proposed modification / addition in the existing system to comply with applicable standards with back-up support / calculation for proposed changes.
- Survey and suggest surge protection for the electronic equipment like DCS / Remote Field instruments / VFDs.
- Suggest Maintenance practices for the lightning protection system installed / suggested.
- Provide detailed specification for the equipment needs to be installed for modification.
Lightning protection of Oil Tanks:
- Impulse (1) : 10/350µs of simulated lightning pulse
- Impulse (2) : 8/20 µs of simulated overvoltage pulse
Risk assessment together with the determination and application of measures to reduce the risk of damage to structure, services and life hazard should all be considered in order to comply with the requirements of This guide covers the assessment and reduction of risk below tolerable levels, together with techniques for the protection against lightning and touch and step voltages of:
- * structures, their services, contents and persons within;
- * services connected to the structure.
Lightning & Surge Protection is based on the following Standards:-
- IS 2309 - 2005: Protection of Buildings and Allied Structures Against Lightning.
- IEC 62305 – 1: Protection against lightning - Part 1: General Principles
- IEC 62305 – 2: Protection against lightning - Part 2: Risk Management
- IEC 62305 – 3: Protection against lightning - Part 3: Physical damage to structures and Life
- IEC 62305 – 4: Protection against lightning - Part 4: Surge Protection of equipment
- OISD GDN 180: Oil Industry Safety Directorate - Lightning Protection guidelines
- IS 3043 – 2006: Code of Practice for Earthing (First Revision)
- IS 7689: Code of Practice against Static Charges
- NFPA 780 – 2008 : Standard for the installation of Lightning Protection Systems
- API RP 2003 – American Petroleum Institute – Lightning Protection Standard
- IEEE 998 – Guide for Direct Lightning Stroke Shielding of Substations