EARTHING AND LIGHTNING OVERVOLTAGE PROTECTION FOR PV PLANTS
cover flashage.qxp Layout 1 11/4/16 1:40 PM Page 1EARTHING AND LIGHTNINGOVERVOLTAGE PROTECTIONFOR PV PLANTSA GUIDELINE REPORT - NOVEMBER 2016Empowered lives.Resilient nations.Ministry of Energy and WaterGround Floor, Corniche du FleuveBeirut, LebanonT: 961 – 1 – 565 090www.lb.undp.org/DREGUNDP is the UN’s global development network advocating for change and connections countries to knowledge, experience and resources to help people build a better life.Empowered lives.Resilient nations.
EARTHING AND LIGHTNINGOVERVOLTAGE PROTECTIONFOR PV PLANTSA GUIDELINE REPORT - NOVEMBER 2016Empowered lives.Resilient nations.
Author:Xavier Vallvé, Trama TecnoAmbiental (TTA)Co-Authors:Maria Anzizu, Trama TecnoAmbiental (TTA)Mariano Ribas, Trama TecnoAmbiental (TTA)UNDP DREG Reviewers:Mr. Jil AmineMr. Eric El ObeidCopyright UNDP / DREG – 2016Reproduction is authorized provided the source is acknowledged and provided thatthe reproduction is not sold. The United Nations Development Programme (UNDP) isthe UN’s principle provider of development, advice advocacy and grant support. Withapproximately 170 country offices, the UNDP has long enjoyed the trust andconfidence of government and NGOs in many parts of the developing, as well as, thedeveloped world. It is typically regarded as a partner rather than as an adversary, andits commitment to universal presence proved especially useful in post–conflictsituations and with states that have been otherwise isolated from internationalcommunity.For further information:United Nations Development Programme, www.lb.undp.orgDREG, www.lb.undp.org/DREGNote: The information contained within this document has been developed within a specificscope, and might be updated in the future.AcknowledgementThe UNDP would like to thank the Global Environment Facility for its donation of fundsthat enabled this study to be carried out through the DREG project.The UNDP would also like to thank all its partners including the Ministry of Energy andWater, Électricité du Liban (EDL), the Council for Development and Reconstruction(CDR), the Lebanese Center for Energy Conservation (LCEC), and Lebanese renewableenergy companies that assisted in the development of this report.
TABLE OF CONTENTSList of FiguresList of Tables12. Introduction1.1 The Assessment Procedure22. Earthing2.1 Earthing Review2.1.1 Direct Contact2.1.2 Indirect Contact2.1.3 Definitions2.1.4 Classification of Components2.1.5 Types of Connections2.1.6 Types of Earth Electrode Installation Methods2.1.7 Earth Resistance Measurement2.1.8 Standardized Earthing Schemes2.2 Earthing System Assessment Procedure2.2.1 Steps of the Earthing Assessment Procedure2.3 Earthing at PV Plants2.3.1 Plants without galvanic isolation2.4 Review of Relevant Standards2.4.1 Functional Earthing2.4.2 Safety Issues2.4.3 Functionally Earthed33. Lightning Overvoltage3.1 Review3.1.1 Characterization of the Lightning Wave3.1.2 Transient Overvoltage3.2 Lightning Risk and Protection Assessment Procedure3.2.1 Equipment Classification – Overvoltage Categories3.2.2 Types of SPDs – Classification3.2.3 SPD Normative Definition3.2.4 Characteristics of SPDs3.2.5 Use of SPDs3.3 Example Case Scenarios3.4 Notes About Relevant RegulationAnnex I: Complete Risk Assessment Process for PV Plants44. Other Transient Overvoltage4.1 Assessment ProcessReferences
2016 A Guideline ReportLIST OF FIGURES4Figure 1General Procedure to assess and select suitable earthing scheme and lightningovervoltages protections for PV plantsFigure 2Direct (left) and indirect (right) contact representations. (Source: Schneider Electric)Figure 3Components of an earthing system (Source: Schneider Electric)Figure 4Buried ring earthing (Source: Schneider Electric)Figure 5Earth rods connected in parallel (Source: Schneider Electric)Figure 6Vertical plate (Source: Schneider Electric)Figure 7Measurement of the resistance to earth of the earth electrode of an installationby means of an ammeter (Source: Schneider Electric)Figure 8TT System (Source: Schneider Electric)Figure 9TN-C System (Source: Schneider Electric)Figure 10TN-S System (Source: Schneider Electric)Figure 11TN-C-S System (Source: Schneider Electric)Figure 12IT System (Source: Schneider Electric)Figure 13Steps of the earthing assessment procedureFigure 14Floating PV plantFigure 15PV plant with a functionally earthed systemFigure 16Exposed conductive parts in a PV system in a floating earthing systemdownstream the transformerFigure 17Current fault example in a floating PV PlantFigure 18Current fault example at a plant without galvanic isolationFigure 19Wave shape and intensities of positive (ground to cloud) and negative (cloud toground) discharges (left). The measured values for intensity of lightning peakcurrent range from hundreds of amperes to several hundred of kiloamperes (right).Figure 20Direct strike wave modelFigure 21Indirect strike wave modelFigure 22Steps of the lightning protections assessment processFigure 23World lightning map (Source: NASA)Figure 24Iso-keraunic map of Europe (Source: Met Offce)Figure 25Proposed process for selecting SPD type (Source: Schneider Electric)Figure 26Recommendation for electric switchboard wiringFigure 27Case 1: Building without external LPSFigure 28Case 2: Building with external LPS and sufficient separation distanceFigure 29Rolling sphere method exampleFigure 30Angle method exampleFigure 31Case 3: Building with external LPS and insufficient separation distanceFigure 32Risk Assessment methodology IEC 62305-2Figure 33Switching operations risk assessment method
Table IComponents of an electrical installation considered as Exposed-ConductiveParts (Source: Schneider Electric)Table IIComponents of an electrical installation not considered as Exposed-ConductiveParts (Source: Schneider Electric)Table IIIComponents of an electrical installation considered as Extraneous-ConductiveParts (Source: Schneider Electric)Table IVComponents of an electrical installation not considered as ExtraneousConductive-Parts (Source: Schneider Electric)Table VResistivity ranges per type of soilTable VIComparison of system earthing arrangementsTable VIIInfluence of networks and load son the selection of system earthingarrangementTable VIIIRequirements for different system types based on type of power conversionequipment’s isolation and PV array functional earthing (IEC 62548)Table IXRated current requirements for not installing an automatic disconnectingdevice (Source: IEC62548)Table XRequired impulse withstand voltage depending for each overvoltage categoryTable XIImpulse withstand voltage to be used when no information is available (Source:IEC 60364-7-714)Table XIIClassification of recommended SPD type for direct and indirect lightning strikesTable XIIIStipulated minimum value of Uc for SPDs depending on the system earthingarrangement (based on Table 53C of the IEC 60364-5-53)Table XIVTable of Iimp values according to the building’s voltage protection level (basedon IEC 62305-2)Table XVRisk relative to the building’s location2016 A Guideline ReportLIST OF TABLES5
1INTRODUCTIONThe Small Decentralized Renewable Energy Power Generation Project, also known asDREG, is funded by the Global Environment Facility (GEF) and implemented throughthe United Nations Development Programme (UNDP). DREG is executed nationallyby the Ministry of Energy and Water (MoEW) in coordination with the Lebanese Centerfor Energy Conservation (LCEC). The project’s objective is to reduce greenhouse gasemissions by the removal of barriers to assist in the distribution and application ofdecentralized renewable energy power generation.Part of the project’s activities includes focusing on local capacity building. In this regard,DREG organized a workshop in Beirut on Earthing and Lightning Overvoltage Protectionsfor PV Systems that was attended by 40 professionals. As a result of the workshop, thisguideline came about; it is a working document that principally focuses on PV plantsthat are embedded in clients’ electrical installations. It should be noted that, typically,the DC PV generator will be within the client’s premises on a rooftop, façade, or groundmounted.This guideline does not pretend to be exhaustive; but in the absence of a Lebanesesafety code to adhere by, it addresses earthing and overvoltage protection aspects inPV plant design considering the local context. This guideline summarizes some of therelevant international standards, manufacturer’s application manuals, and bestpractices among local electrical engineering practitioners.This guideline is divided in three main sections; (1) earthing; (2) lightning overvoltage;and (3) other transient overvoltage. In each section, a risk-mitigation procedure hasbeen defined considering the physical and electrical principles behind them, the risksand their causes, and local common practice.2016 A Guideline ReportThis guideline is complementary to required technical and financial assessments suchas energy performance or space availability, interconnection, etc., which are alsocarried out as part of a feasibility study.61.1 The Assessment ProcedureThis guideline aims at establishing a common and general procedure to ensure safetyfor persons and equipment in PV plants. Due to the PV market’s developmentcharacteristics that can be foreseen in Lebanon, it focuses on PV plants that areinterconnected to a client’s electrical distribution grid. In most cases, these will be
01 INTRODUCTIONrooftop PV plants, but most of the procedures and protection measures suggestedalso apply to ground-mounted PV plants.The general procedure consists of a set of three separated procedures, which shouldbe followed by project engineers to ensure that a PV plant is safe for both people andequipment, and plan additional protective measures in case a need is there.This guideline also highlights the most relevant international standards and somephysical principles that explain the causes and risks related to both lightning andearthing.It contains three procedures, which specifically refer to each one of the three topicscovered. These topics are: (1) earthing; (2) lightning overvoltage; and (3) othertransient overvoltage.General Procedure2. Lightning riskassessment1. Earthingprocedure3. Other transientovervoltagesassessmentEach of the steps provides a set of instructions that focus on assessing the currentstatus of the system – either the earthing system or protection against transientovervoltage – and they figure out whether the safety level provided by the system issufficient, and, once the safety level has been assessed, provide a number of protectivemeasures to be taken in order to ensure the PV plant is safe.2016 A Guideline ReportFigure 1 - General Procedure to assess and select a suitable earthing scheme andlightning overvoltage protection for PV plants7
INTRODUCTION2 EARTHING2.1 Earthing ReviewWhy is the earthing system important?The aim of earthing in electrical installations and circuits is to enhance the safety of theinstallation by reducing the level of danger inherent to fault currents. Fault currentsmay be caused by different factors. Therefore, it is very important to design an earthingsystem according to the installation’s characteristics. Purpose of an earthing system:- Provides safety for persons and animals- Protects the installation and equipment- Enhances quality of signal (reduced electromagnetic distortion)- Provides a fixed reference voltage for equipotentialization Factors to consider at the design stage of an earthing system:- Soil humidity (reduces earthing resistance)- Earthing enhancing devices reduce soil resistance- Buried electricity and gas installations require security distances- Buried pipes and water tanks shall be bonded equipotentially with earth terminationFault currents can be transmitted to persons and animals, presenting a high riskthrough both direct and indirect contact. 2016 A Guideline Report2.1.1 Direct Contact Direct contacts is defined as an event caused by a person or animal getting in contactwith a live conductor of the electrical installation or a normally live conductiveelement. To prevent these events:- Insulating cables (with proper insulating materials)- Using instantaneous High Sensitivity Residual Current Devices known as HS-RCDs. Direct contact protection is independent from the system earthing.82.1.2. Indirect Contact Happens when a person or animal gets into contact with an exposed-conductive-part. It is the result of an insulation fault that creates a fault current flowing. At the sametime, the fault current raises the potential between the devices’ frame and the earth,thus causing a fault voltage. The fault voltage is considered to be dangerous if it exceeds the Upper Limit voltage.
02 EARTHINGIn order to prevent Direct and Indirect Contacts, the International ElectrotechnicalCommission (IEC) gave official status to three earthing systems and defined thecorresponding installation and protection rules.IEC 60364 defines three standardized earthing systems schemes: Exposed-conductive parts connected to neutral -TN Earthed neutral -TT Unearthed (or impedance-earthed) neutral -ITThe purpose of all these three earthing systems is the protection of persons andproperty. They are also considered to ensure safety of persons against indirectcontacts.Figure 2 - Direct (left) and indirect (right) contact representations (Source: Schneider Electric) Earth electrode (1): conductor or group of conductors in intimate contact with, andproviding an electrical connection with Earth. Earth: refers to the conductive mass of the Earth – potential conventionally taken aszero. Electrically independent earth electrodes: earth electrodes placed at a distancethat allows a maximum current flowing through one of them not significantlyaffecting the potential of the others. Earth electrode resistance: The electrical resistance of an earth electrode with Earth. Earthing conductor (2): protect
IEC 60364-7-714) Table XII Classification of recommended SPD type for direct and indirect lightning strikes Table XIII Stipulated minimum value of Uc for SPDs depending on the system earthing arrangement (based on Table 53C of the IEC 60364-5-53) Table XIV Table of Iimp values according to the building’s voltage protection level (based on IEC .
bq2431x Overvoltage and Overcurrent Protection IC and Li Charger Front-End Protection IC 1 1 Features 1 Provides Protection for Three Variables: – Input Overvoltage, With Rapid Response in 1 μs – User-Programmable Overcurrent With Current Limiting – Battery Overvoltage 30
Earthing & lightning protection A real & significant threat Lightning is one of nature’s most powerful and destructive phenomena. Lightning strikes present a real and significant threat to life, to the structures in which we live and work, and to the electronic systems which support us
ABB OPR lightning protection systems 1 Lightning mechanism and location 2 Lightning protection technologies 3 Lightning protection risk analysis 8 Lightning protection technical study 9 Procedure for measuring the Earl
Creating new Lightning Page using Lighting App Builder Salesforce Lightning pages can be created using Lightning App Builder. To create, navigate to Build Lightning Bolt Lightning App Builder New. Lightning App Builder - App page. In this step, select App page and click on next button as shown below. Lightning App Builder
IEC 62305-1 -4 (01/2006) Lightning protection system (general principles) Interception systems Conductors Earthing Proximities Lightning protection equipotential bonding Shielding of enclosed spac
bq24314A Overvoltage and Overcurrent Protection IC and Li Charger Front-End Protection IC 1 Features 3 Description The bq24314A device is a highly integrated circuit 1 Provides Protection for Three Variables: (IC) designed toprovide protection Li-ion batteries – Input Overvoltage, With
Session 2: Power & Lightning (Surge) Protection February 17, 2021 U.S. Power Generation Facility Lightning Protection NFPA 780 and IEC 62305 were chosen for comparative study for Lightning Protection of U.S. Power Generation Facility as these two standards are the two most widely accepted lightning protection standards.
The report of last year’s Commission on Leadership – subtitled No More Heroes (The King’s Fund 2011) – called on the NHS to recognise that the old ‘heroic’ leadership by individuals – typified by the ‘turnaround chief executive’ – needed to make way for a model where leadership was shared both ‘from the board to the ward’ and across the care system. It stressed that one .
