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Modern lightning protection systems for wind turbine blades with conducting structural elements, e.g., carbon fiber reinforced polymer (CFRP) spar caps, contain equipotential bonding joints to prevent sparking during strikes. Significant current levels are experienced through the joints and the characterization of the electrical contact at the bonding regions is essential for reliable protection. Therefore, this article aims to characterize the contact resistivity of several equipotential bonding joints. The proposed methodology first measures the total resistance of the samples, and then the bulk resistance of the conductive elements is computed using the finite-element method. The latter is required to predict the spreading effects in CFRP components due to the strong anisotropic nature of such materials. After that, the contact resistance is calculated by subtracting the predicted bulk resistances from the measured total resistances. The developed procedure was applied to three typical equipotential bonding materials: expanded copper foil (ECF), biaxial (BIAX) CFRP, and unidirectional (UD) CFRP. Both ECF and BIAX CFRP showed superior contact quality than the UD CFRP, with one to two orders of magnitude smaller contact resistivity.

Different conductive bonding strategies for the hybrid integration of flexible, inkjet-printed electronics are investigated. The focus of the present work lies on providing a practical guide comprising standard techniques that are inexpensive, easily implementable and frequently used. A sample set consisting of identical conductive test structures on different paper and plastic substrates was prepared using silver (Ag) nanoparticle ink. The sintered specimens were electrically contacted using soldering, adhesive bonding and crimping. Electrical and mechanical characterization before and after exposing the samples to harsh environmental conditions was performed to evaluate the reliability of the bonding methods. Resistance measurements were done before and after connecting the specimens. Afterwards, 85 &deg, C/85% damp-heat tests and tensile tests were applied. Adhesive bonding appears to be the most suitable and versatile method, as it shows adequate stability on all specimen substrates, especially after exposure to a 85 &deg, C/85% damp-heat test. During exposure to mechanical tensile testing, adhesive bonding proved to be the most stable, and forces up to 12 N could be exerted until breakage of the connection. As a drawback, adhesive bonding showed the highest increase in electrical resistance among the different bonding strategies.

This article analyzes the lightning transients in a commercial building with a grid like structure. The simulation is performed by using the partial element equivalent circuit method. Both the skin effect of the conductors and the nonlinear protection devices are taken into consideration. The induced voltage and the current sharing in the wiring system of both rising main circuit and secondary circuit are discussed. The influence of soil resistivity, lightning current waveform, different surge protection devices (SPDs) installations, and equipotential bonding are analyzed in this article. According to the simulation results, the soil resistivity can largely influence the potential of the conductor; however, it has a limited influence on the voltage between electric wires (potential difference). The SPDs installation arrangement and the equipotential bonding position in the building can greatly influence the lightning transients. The overvoltage and current can largely reduce if they are installed at a proper position. The suggestions provided in this article are constructive while designing the lightning protection system in buildings.

The main objective of this paper is to evaluate the maximum share of the lightning current, which enters a building on electric installation lines. The conductors of the power circuit are equipotentially bonded to the air-termination or down-conductor system at roof level. For live conductors, the lightning equipotential bonding is realized by the use of surge protective devices (SPD), which have to withstand the threat of the share of the lightning current. The most important parameter is the maximum transferred charge, which was calculated by the use of the computer code CONCEPT II. The maximum expected charge is about 0.6 C for buildings with metal facades. If the building is additionally equipped with a metal roof, or, if the roof, the ceilings and the pillars/walls consist of reinforced concrete, the maximum expected charge is 0.1 C. For buildings without shielding elements (metal roof, metal facade, reinforced concrete), the charge is much higher, in the range of several coulombs. The values only apply to spark-type SPD and to building up to heights of about 15 m using copper or aluminum for the air-termination and down-conductor system. The transferred charge is significantly higher, if the air-termination and down-conductor system consists of stainless steel.

Equipotential bonding, whereby objects are connected to a common electrical potential (usually ground) to prevent electrostatic discharges during material handling, has been shown to increase the risk of field-induced reticle damage. It is explained how the presence of an electric field can cause electrostatic damage in a reticle without a discharge event taking place. A comparison is drawn between the damage mechanisms that can take place in reticles and in semiconductor devices. The use of equipotential bonding during the manufacture of electrically sensitive semiconductor and micro-electro-mechanical systems is discussed. It is concluded that while equipotential bonding eliminates the risk of ESD during material handling, it simultaneously creates other risks for the devices being manufactured, which has the potential to introduce latent defects. An alternative methodology for dealing with electrostatic risk in semiconductor manufacturing is proposed, which would eliminate the undesirable enhancement of field-induction effects that is a consequence of using equipotential bonding.

This paper presents a novel numerical approach to simulate lightning strike damage to equipotential bonding interfaces of wind turbine blades, and model validation based on high-current testing. Modern rotor blades are equipped with metal receptors to intercept the lightning leader and metal down conductors to conduct the lightning current, preventing the direct attachment to the CFRP spars. In such conditions, damage in the form of resin thermal degradation and sparks develop inside the blade at the equipotential bonding interfaces. Excellent correlation was found between the numerical predictions and test results in terms of current and temperature distributions. High temperatures were predicted at the sparking areas observed in the tests, which suggested that the damage is thermally activated. Thermogravimetric analysis data indicated that the epoxy pyrolysis process evolves in stages, and that sparking events are often initiated by release of gases and formation of small voids at temperatures lower than expected.

Touchable parts of electrical products and equipment can be thermally hot. Unintentional contact with hot surfaces during the normal operations of products may cause burns, and severity depends on the thermal resistivity of the material of the exposed part, the contact duration, the contact pressure, and skin conditions (i.e., dry, water wet, etc.). Currents flowing through equipment surfaces due to intentional choice or wiring errors can also elevate their temperatures, compounding the thermal effect; this causes an increased risk of triggering explosive atmospheres and fires in locations where combustible/flammable materials are processed or stored. In this paper, in light of applicable technical standards, the authors discuss and propose applicable burn thresholds, and permissible contact times with hot parts, based on different groups of users who may unintentionally touch the surfaces. The risk assessment of burning can be performed by comparing actual maximum temperatures of parts of electrical equipment against safe temperatures that a person may withstand for a given time without suffering a second degree burn.

This paper deals with those measures against overvoltage taken when protecting buildings occupied by people or animals. Such overvoltages can appear in the case of ground fault if the grounding system of the building is located within a potential funnel of a transmission tower's grounding system. This paper presents an entire concept regarding protection against any potential rise within the building. Computations of electrical potential on the grounding system having been performed using data obtained by measurements. This includes equipotential bonding, overvoltage protection of the building, and a transformer substation with metal–oxide varistors and gas-discharge arresters installed on the low-voltage line. A simulation model for the entire overvoltage protection based on known mathematical models has been merged within this paper. Adequate overvoltage protection elements were selected for protection against potential rises in the grounding systems of buildings on the basis of computation results.

Wind turbines are more and more often erected in remote areas of the world, in order to exploit better wind conditions. In these areas the cost of failures and repairs can be substantial. For this reason ensuring the lightning performance of the turbines and especially of the blades has become very important.Modern blades are to a large extent manufactured using Carbon Fiber Composite (CFC) structural parts, due to the CFC’s excellent mechanical tensile strength and stiffness, combined with a light weight. However, Carbon Fiber Composites also exhibit highly anisotropic electric conductivities, which require special attention in terms of lightning protection, primarily in what concerns electrical bonding. The present paper presents the latest findings on how to include CFC materials in wind turbine blades into the lightning protection coordination, both in terms of engineering analysis using modern numerical tools, as well as with experimental validation in the lightning test facility. The paper is part of the EU funded project SPARCARB which started January 1st 2015 and which aims at exploring the details of lightning interactions with CFC materials, damage mechanisms, optimization of electrical/thermal properties by adjusting the chemical composition of resin, fiber sizing, weaving techniques, manufacturing processes, etc.

International (IEC) European (CENELEC) and American (NEC) Standards require, in each building, the connection of extraneous conductive parts (i.e. metal water or gas pipes) to the main grounding terminal. There are two good reasons for this: the voltage between extraneous conductive parts and exposed conductive parts is zeroed and extraneous conductive parts can contribute to the leakage of fault current into the ground. There is however a third advantage in the bonding connection: the entire structure (floors and walls of the building), together with the exposed and the extraneous metallic parts, forms a quasi-equipotential system, with the consequent strong reduction of touch voltages. Metallic pipes and reinforcement of reinforced concrete have a particular relevance thanks to their large widespread through buildings. However, in some practical cases, it is not possible to connect all extraneous conductive parts to the protective equipotential bonding because they are not accessible. In the paper, the reduction of touch voltages in buildings, when these extraneous conductive parts are present but not connected to the protective equipotential bonding is quantified. Different building models are created and solved by the finite element method in order to calculate touch voltages in different scenarios. The results show that the mere presence of widespread metallic parts in buildings helps to reduce touch voltages, but not enough to ensure safety against indirect contacts. The electrical installation safety performance is greatly improved in reinforced concrete buildings if at least some easily accessible parts, like water or central heating pipes, are connected to the main grounding terminal. Also in brick buildings, they provide a certain reduction of GPR, maximum and mean touch voltages.

Carbon fibre reinforced polymers (CFRP) are increasingly used for structures on aircraft due to their superior mechanical properties compared to traditional materials, such as aluminium. Additionally, in order to improve aircraft performance, there is a continued trend for electrically driven loads on aircraft, increasing the on-board electrical power generation capacity and complexity of the electrical power system, including a desire to increase voltage levels and move towards DC distribution systems. Central to the reliable operation of an electrical power system is the development of an appropriate protection and fault management strategy. If an electrical earth fault occurs on a composite more-electric aircraft then the CFRP may form part of the route to ground. In order to develop an appropriate protection system and thus to understand the effects on engine generators it is necessary to investigate the fault response of this network. Hence a suitable electrical model of the CFRP material is required, which will enable CFRP to be included in a computationally-intensive systems-level simulation study of a more-electric aircraft (MEA) with fully switching power electronic converter models. This paper presents an experimentally validated impedance model of CFRP at an appropriate level of fidelity for use in systems level simulation platforms, enabling appropriate protection methods to be developed. The validated model considers the impact of the electrical bonding to ground, including the impedance added by a metallic frame that a CFRP panel may be mounted in. The simplicity of the model results in a less complex process to determine the expected impedance of the CFRP material, enabling a focus on the fault response of the system and subsequent development of appropriate protection solutions.

An ordinary life area has numerous structures, systems, buildings, objects and components that are susceptible to lightning strikes. The effects of strikes can include actuation of safety systems, and loss of living areas. Protection of critical structures and applying necessary protection measures should be determined in terms of risk, completely risk management. The paper deals with results of investigation on efficiency of internal protection. The attention has been paid to the efficiency of the shields and to their kinds, arrangement, equipotential bonding and grounding according to the concept of lightning protection zones (LPZ).

This paper describes the verification test on Electromagnetic Environmental Effects(E3), which conducted on ground as a final step to confirm the normal operation of ELINT pod and Safety-of-Flight of KF-16C/D mounted with ELINT pod prior to the initial flight. Based on MIL-STD-464A, indispensable 7 requirements among 14 detailed requirements total were carried out in the test. Considering the Safety-of-Flight(SOF), we invest a great deal of time and effort on Hazards of Electromagnetic Radiation to Ordnance(HERO) and Intra-system EMC test. E3 test and evaluation were performed on 62 equipments of KF-16C/D, respectively. As a result, we verify that KF-16C/D mounted with ELINT pod(hereafter "system") are electromagnetically compatible among all subsystems and equipment within the system and with environments caused by electromagnetic effects external to the system.

This paper provides comprehensive analysis on the lightning protection scenarios in 48 communication and broadcasting towers situated in similar isokeraunic contours in Sri Lanka at 79°–81° East and 5°–10° North. The investigation has been conducted to study the hazardous environment created on the tower and in the neighbourhood in the event of a lightning strike to the tower. The results show that a direct strike to an antenna structure in a metallic tower is rare irrespective of the presence of an air-termination or a down conductor. However, side flashing or arcing to antenna structures is highly possible once the air-termination and/or down conductor is installed and attempts are made to insulate the system from the tower. The outcome also shows that equipotential bonding of the grounding system, a distributed grounding network including a ring conductor and a suitable system of surge protective devices play a much vital role in lightning protection of equipment and safety of people compared to the effects of simply achieving a low grounding resistance. However, in the absence of such integrated, distributed and equipotentialized grounding system, a high value of ground resistance will sharply increase the possibility of accidents and damage. Considering the observations of the investigations into account we have designed a concrete embedded grounding system for tower sites at problematic locations. Finally, the scenarios for safety management at telecommunication tower sites have been discussed.

Antennas, if present on roofs, are, usually, the most prominent part of edifices. Grounding their metal supports is, generally, considered an effective means of protection of the structure against the effects of lightning strokes, eventually “attracted” by the antennas themselves. The antenna's mast and the down conductor are incorrectly assumed capable of safely draining to ground the lightning current flowing at the point of strike. This, supposedly, would prevent both hazard for people and damage to the building and electrical equipment situated inside of it. This paper will substantiate how the sole grounding of the antenna's mast can instead result in lowering the safety of the edifice, and, thereby, expose users to the hazard of dangerous electrical sparking (flashover) and possible fires.

This paper explains how an electric field and a reticle interact and describes the different kinds of damage that can be caused to a reticle through its exposure to electric field. It is shown why electrostatic reticle damage has changed from ESD damage (which causes yield to suddenly drop precipitously) into a gradual and cumulative form of degradation that is very difficult to diagnose. It is explained why some of the approaches that have been taken to reduce ESD damage in the semiconductor factory, such as equipotential bonding and the use of static dissipative plastics for making reticle pods, actually increase the risk of this cumulative type of electrostatic degradation in reticles. When assessing the risk to reticles and designing an effective protective strategy for reticle handling, it is shown why one must take into account the temporal characteristics of a reticle’s interaction with electric field—including the effect that the reticle’s immediate surroundings will have on that interaction—as well as considering the strength of any electric field in the reticle handling environment. Solutions are presented that would allow the electrostatic risk to reticles to be reduced significantly, without requiring major changes to operating procedures in semiconductor manufacturing facilities.

Lightning current distribution in a directly hit building is studied by using a simple equivalent circuit and an electromagnetic model. The Numerical Electromagnetics Code (NEC-4) is employed for numerical electromagnetic analysis. The error in the shunt ratio of lightning current entering wiring, which is calculated using the electromagnetic model, is estimated to be less than 4%. The shunt ratios for lightning current entering the wiring on the top floor and the first floor are largest. Although they are larger for a higher building, they are almost constant if the building struck has more than five floors. They are smaller when there are more vertical conductors, or the length of the wiring is longer. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 159(1): 9–16, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20449

In low-voltage systems, ground-faults do not necessarily involve the actual earth, but fault currents may return to the source via conductors; such conductors, which provide a clear path toward the source, are defined in applicable codes and technical standards as equipment grounding conductors or protective conductors. The above situation is for example typical of the North American low-voltage multiple grounded distribution systems, also referred to as TN-C-S, in international standards (IEC). In this paper it is substantiated that under ground-fault conditions even healthy equipment, sharing the same protective conductor with faulty equipment, as well as any metalwork in the building, acquire electrical potentials. Such potentials have a decreasing magnitude toward the electrical source and keep the same constant value on equipment located downstream the ground-fault location. The presence of non-zero potential differences between exposed-conductive-parts is a salient trait of TN systems and may constitute a hazard particularly in special locations, such as bathrooms with showers or bathtubs. In such areas, in fact, the resistance-to-ground of persons may be greatly reduced by moisture, water or the absence of clothing. This paper illustrates the advantages of supplementary equipotential bonding connections in such locations as a possible solution in the reduction of latent potential differences.

Earthing is the foundation of lightning protection of the RBS (radio base station), providing a way for discharging the lightning current. Equipotential bonding can protect equipment from lightning attack, providing a potential reference point for all equipment. There are two methods for the equipotential bonding. The first is the constant bonding, that is, equipment are grounded directly through earthing wire and the other is the instant bonding which should be used for the earthing through SPD (Surge Protective Devices). The paper will discuss the implementation problems on equipotential bonding of the RBSs. Keywords—Earthing, Equipotential, Optimization, Bonding I. SUMMARY For the lightning protection of RBS, the problem of the equipotential bonding has always been talking about. The earthing of RBS is necessary and foundational. Till now, many technicians have only focused on the connection of devices which can be earthed directly; Some people mistakenly think SPD is not useful for they ignore an important issue: how to implement connection for many systems, such as power supply, signal ports that can not be earthed directly in the RBS.

In this paper we analyze the lightning protection system of 48 communication and broadcasting towers situated in similar isokeraunic contours in Sri Lanka. The results show that a direct strike to an antenna structure in a metallic tower is rare irrespective of the presence of an air-termination or a down conductor. However, side flashing or arcing to antenna structures is highly possible once the air-termination and/or down conductor is installed and attempts are made to insulate the system from the tower. The outcome also shows that equipotential bonding of the grounding system, a distributed grounding network including a ring conductor and a suitable system of surge protective devices play a much more vital role in lightning protection of equipment and safety of people than simply achieving a low grounding resistance. However, in the absence of such integrated, distributed and equipotentialized grounding system, a high value of ground resistance sharply increases the possibility of accidents and damage. Considering the observations of the investigations into account we have designed a concrete embedded grounding system for tower sites at problematic locations with respect to ground resistivity. The system performance has been tested by implementing the system at two tower sites and observing the performance for 3 years.

The paper deals with the characteristics of a lightning protection system (LPS) for a fixed and a mobile radars. The LPS design includes external (LPE) and internal (LPI) system as well as protection measures against lightning electromagnetic pulse (LEMP) of internal electrical and electronic systems (i.e. air terminations, down conductors, earthing arrangement, internal equipotential bonding. cable routing and shielding and surge protection) according to the IEC 62305 standard series. By means of computer simulations the most critical parameters have been evaluated and the results have been taken into account both in the electrical design of the LPS and in the selection of some radar components.

Summary form only given. The following discussion relates to the above paper [1]. Grounding is one of the most misunderstood aspects of electrical power systems, and the transferred earth potentials component of power system grounding is even less understood. I read this paper with great interest and wish to commend the authors for tackling the subject-particularly as it relates to worker safety within their country, especially since it is counter to existing practices. Having been in 30 different countries and observing installations worldwide, it is very apparent to me that safety grounding is commonly misunderstood worldwide. The reference to investigating other accidents that had been “closed” without finding the cause speaks to this point. The authors correctly identified the transferred earth potential and that it was the greater risk (I called it “transfer by grounded conductors” in reference [5] of [1]). This speaks to the need for using insulated boom trucks, always using insulated gloves, bonding the metal poles below their feet to the temporary ground, and working through practices that involve the equipotential bonding mentioned. Further details addressing wood and cement poles are a logical extension of their work. It is my hope that the authors can leverage their work with this paper to educate and affect real change in safety practices within India and elsewhere.

Surge overvoltages result in a power system from overcurrents due to atmospheric discharges, induction phenomena, switch operations or faults. In order to reduce the probability of injuries to people and of failure of electrical and electronic systems, power systems within a structure should have adequate equipotential bonding. Surge protective devices (SPDs) are used to achieve such equipotential bonding. Metal Oxide Varistors (MOVs) are a very often used kind of SPDs. Actually, MOVs are affected by ageing, due to the number and amplitude of stresses, but also due to other factors such as overheating, pollution and humidity. The aim of this paper is to present a probabilistic assessment of the ageing process of MOVs when lightning, switching and temporary overvoltages are considered. The expected life thus obtained can be used to decide (logistic/maintenance procedures) when the MOV must be changed before its failure occurs, since the main standards do not give definitive indications about such feature.

This paper deals with the results of investigation on the efficiency of external and internal grid-like spatial screens as a measure of internal protection. Attention has been paid not only to the efficiency of the screens but also to their kinds, arrangement, equipotential bonding and grounding according to the concept of lightning protection zones. It was emphasized that the external screen—in general—is more efficient than the internal one.

This study has established the need for low resistance electrical bonding between a cathodically protected and an unprotected ship when berthed together. On the basis of three series of electrical measurements, a maximum bonding resistance of 0.0005-ohm is recommended. Calculations based on these measurements show that an instance of severe underwater hull corrosion was attributable to inadequate bonding of an unprotected ship to a cathodically protected ship berthed alongside. 5.2.5