Alexander Kern

Calculation of interception efficiencies for air-terminations using a dynamic electro-geometrical model

The paper firstly presents the method of a dynamic electro-geometrical model. In contrast to the classic rolling-sphere it does not use fixed radii, it works with a varying radius. The method only uses existing and in international standards accepted results, fundamentals of lightning physics, and investigations; on that base a numerical method is elaborated. Using the dynamic electro-geometrical model, secondly some examples of protection with air-termination rods planned with the classic rolling-sphere according to IEC 62305-3 and for the classes of protection I–II–III–IV are investigated. It is shown, that the interception efficiencies are much higher than documented in the standard series IEC 62305. Reason is, that the method of the rolling-sphere is conservative, and that it gives the planner of lightning protection systems only the points, where lightning may strike, but without a rating with a striking probability. On the other hand this result clearly indicates, that using the classic rolling sphere method one is always on the “safe side”.

How to deal with environmental risk in IEC 62305-2

The 2nd edition of the lightning risk management standard (IEC 62305-2) considers structures, which may endanger environment. In these cases, the loss is not limited to the structure itself, which is valid for usual structures. In the past (Edition 1) this danger was simply taken into account by a special hazard factor, multiplying the existing risk for the structure with a number. Now, in the edition 2, we add to the risk for the structure itself a “second risk” due to the losses outside the structure. The losses outside can be treated independently from what occurs inside. This is a major advantage to analyze the risk for sensitive structures, like chemical plants, nuclear plants, or structures containing explosives, etc. In this paper, the existing procedure given by the European version EN 62305-2 Ed.2 is further developed and applied to a few structures.

Calculation of interception efficiencies for mesh-type air-terminations according to IEC 62305-3 using a dynamic electro-geometrical model

Interception efficiency is the most important parameter to show the effectiveness of air-terminations. With the dynamic electro-geometrical model, a numerical method, it is possible to calculate such interception efficiencies. This model is based purely on internationally accepted models, parameters, and dependencies. So far it is used to calculate the interception efficiencies for rod-type air-terminations. An adaption of this model allows the calculation of interception efficiencies for mesh-type air-terminations. Up to now the effectiveness of this kind of air-terminations could only be shown on an “empirical base”. This gap could be closed now using the results of this paper.

Future evolution of risk management for structures advancement for the future IEC 62305-2 Ed3

The actual version of risk management for structures was issued 2010–12 in IEC 62305-2 Ed2. Enduring discussions show the necessity of a further development towards Ed3. This document offers the evolution of an advanced risk management. Based on its revised definitions, the actual problems are analyzed and solved. All terms are deeply discussed and the relevance of the new solution is shown in comparison with the old and new results for the hospital example of IEC 62305-2 Ed2.

Probability and frequency of damage of electrical and electronic systems due to indirect lightning flashes

In the present paper data collected from the field related to the damage statistics of electrical and electronic systems due to lightning overvoltages are reported. These damages were registered by German insurance companies in 2005 and 2006 in different structures and installations. With the use of stochastical methods it is possible to reassess the collected data and to define cases, which are with high probability caused by lightning overvoltages. The results of the stochastic model are compared with the probability of damage distributions obtained by using the analytical method, which is the basis for the IEC Standard rules.

Detailed calculation of interception efficiencies for air-termination systems using the dynamic electro-geometrical model — Practical applications

Interception efficiency (IE) is the most important parameter to show the effectiveness of air-termination systems. The dynamic electro-geometrical model (DEGM), a numerical method, is capable of calculating such interception efficiencies. This model is purely based on international accepted models, parameters, deviations and dependencies, which are also comprised in the IEC 62305. So far it has been used to calculate the interception efficiencies for rod-type air-terminations. This paper discusses applications using the DEGM. A detailed analysis shows that for a rod-based air-termination system the IE is much better than expected. This leads to the idea of a comparison analysis between an air-termination system purely planned according to the standardized “rolling-sphere” method and an “optimized” air-termination system based on the DEGM.

Number of lightning strikes to tall structures - comparison of calculations and measurements using a modern lighting monitoring system

Using a state-of-the-art lightning monitoring system LM-S with lightning detection sensors based on the Faraday effect the lightning currents caused by direct strikes to different buildings can be analyzed. The lightning monitoring system measures different current parameters, e.g. amplitude, charge, specific energy, time of strike. The measured data are compared with the expected number of strikes calculated based mainly on the international standard for risk management IEC 62305-2 Ed.2:2010 [1].

Risk management according to IEC 62305-2 edition 2: 2010–12 assessment of structures with a risk of explosion

Risk management for structures with a risk of explosion should be considered very carefully when performing a risk analysis according to IEC 62305-2. In contrast to the 2006 edition of the standard, the 2010 edition describes the topic “Structures with a risk of explosion” in more detail. Moreover, in Germany separate procedures and parameters are defined for the risk analysis of structures with a risk of explosion (Supplement 3 of the German DIN EN 62305-2 standard). This paper describes the contents and the relevant calculations of this Supplement 3, together with a numerical example.

Some masterpoints about risk due to lightning

The present paper aims to provide insights for a better and simpler approach to risk assessment due to lightning. Reference is made to the documents recently issued in the frame of the International and European Standards.

Simulation of the transient voltages in the auxiliary power network of a large power plant in case of a direct lightning strike to the high-voltage overhead transmission line

Large power plants can be endangered by lightning strikes with possible consequences regarding their safety and availability. A special scenario is a lightning strike to the HV overhead transmission line close to the power plants connection to the power grid. If then additionally a so-called shielding failure of the overhead ground wire on top of the overhead transmission line is assumed, i.e. the lightning strikes directly into a phase conductor, this is an extreme electromagnetic disturbance. The paper deals with the numerical simulation of such a lightning strike and the consequences on the components of the power plants auxiliary power network connected to different voltage levels.