By Stefan Fassbinder / Published on Mon, 2009-08-17 14:10
It may be normal that in a church an earthing electrode, if any, is directed to the sky, like this one found in Jena / Germany beneath the altar, and not linked to anything "earthly", but under "normal" conditions and from an electro-technical point of view, if there is any sort of electrical installation contained in any building at all, it should also be earthed!
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Earthing Systems
By HDK / Published on Fri, 2009-06-26 08:26
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By Hans De Keulenaer / Published on Mon, 2008-12-08 13:32
Electrical safety of low voltage supply systems is the subject of many national and international standards. Installation rules providing electromagnetic compatibility were introduced during the last decade, but still are not well known to installers and system designers.
From the perspective of electromagnetic compatibility, there must be no operating currents, not even stray currents (as defined in IEC 60364-5-54) flowing through the earth wire and earthing and equipotential bonding system.
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By Bryony Samuel / Published on Wed, 2008-12-03 11:13
This Application Note discusses practical design of earthing electrodes, including the calculation of earthing resistance for various electrode configurations, the materials used for electrodes and their corrosion performance. Equations are given for many common electrode geometries, including horizontal strips, rods, meshes, cable screens and foundations.
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By Bryony Samuel / Published on Wed, 2008-12-03 11:07
This application note proposes a systems approach to the design of the earthing system. It has to perform three functions: conducting lightning and short circuit currents to earth, preventing the dangerous touch and step voltages and providing the low impedance, equipotential environment required for electronic and communication equipment. These functions are apparently contradictory but can be achieved by careful design.
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By Bryony Samuel / Published on Wed, 2008-12-03 11:05
Earthing of electrical systems is very important. Its primary purpose is to ensure safety by providing protection for buildings and occupants against direct damage and electrical shock due to lightning or short circuit events. Its secondary purpose is to provide a noise free equipotential environment to enable electrical and electronic equipment to function correctly and reliably.
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By Guy Kasier / Published on Mon, 2008-06-30 09:59
This aspect differs from producer to producer. With some systems, all modules are supplied in a class II housing. These modules do not have to be earthed.
On the other hand there are producers who bring out class I modules in metal housings (entire or partial) or whose components can be touched on an open printed circuit board. In such case, the provided earthing connection must be used.
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By Stefan Fassbinder / Published on Thu, 2008-03-13 13:34
Occasional reason for complaints: Conflicting statements on the same thing in different standards
Different standards often make divergent statements on the same part or component of an installation. This is because, firstly, one standard deals with electrical safety (e. g. IEC 60364-5-54), another one with functionality and EMC (e. g. IEC 60364-4-44) and possibly yet another with lightning protection (e. g. IEC 62305).
In many cases, the limits given in standards are mere estimates, so the respective bodies, since they all consist of technical experts, will always come to similar, but not necessarily the same limit values! Because standardisation, especially at an international level, is a very complex task, there is often a lack of communication between any two (or even more) bodies dealing with the same object from different perspectives. This is how the conflicting statements come about.
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By Angelo Baggini / Published on Fri, 2008-02-15 15:00
Engineers normally face two tasks when designing earthing systems:
- Obtaining a low earth resistance (impedance) value
- Having a good surface potential distribution (low touch and step voltages)
The properties of the earth electrode arrangement depend significantly upon the earth electrode construction.
This animation shows the most common criteria for choosing schemes for electricity distribution from a technical perspective.
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By Michele De Witte / Published on Tue, 2008-02-05 11:00
The limitation of disturbances caused by fluctuating loads of medium size, at Low Voltage (LV), concerning appliances with input current > 16 A and < 75 A is the subject of this article. Now, why did we develop a practical tool in order to easily assess the disturbances? It's simple: the standards dealing with these issues are not exactly easy in use.
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By Hans De Keulenaer / Published on Fri, 2008-01-18 11:36
By G Zizzo et al
The authors propose a practical approach to facing the problem of designing earthing systems in two-layer soils. This approach is based on the calculation of an equivalent resistivity of the non-uniform soil, through which the designer can treat this one as if it were uniform. The authors' purpose is to provide an simple, innovative method and some easy-to-use graphs for a simple earthing system design in two-layer soils.
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By Hans De Keulenaer / Published on Wed, 2008-01-16 15:09
By A Amezua et al
Neutral treatment is a key issue when an MV network is designed. Requirements of insulation and safety have to be met whilst guaranteeing rapid fault detection, location, arc suppression and tripping, if necessary, within a proper timing. The values of overvoltages and fault currents expected in the network are crucial, since they affect Power Quality parameters, namely interruptions and voltage dips.
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By Hans De Keulenaer / Published on Tue, 2008-01-08 17:27
The Belgian site being studied in this paper is connected to the public transmission grid (380 kV) by a High Voltage (HV) station. This HV station incorporates a 25 kV substation linked to a second substation via 25 kV underground cables. The second substation supplies the electric installations on the site.
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By Stefan Fassbinder / Published on Tue, 2007-11-13 17:02
Earthing is an important issue also for railway systems. A very contentious question is whether such earthing systems should be meshed with that of the public supply, or only single-point connected where possible. Some people say that single-point is not really possible at all, and a full connection is therefore better. Others say that this will not reduce, but facilitate mutual disturbances. For instance...
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By Stefan Fassbinder / Published on Fri, 2007-07-20 20:03
Always make sure there is one and only one conductive connection between the N conductor and the PA/PE system within a TN-S installation, even when there are several star points from several sources feeding into the system!
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By Stefan Fassbinder / Published on Fri, 2007-07-13 18:52
Always make sure there is one and only one conductive connection between the N conductor and the PA/PE system within a TN-S installation, even when there are several star points from several sources feeding into the system! Otherwise the beneficial effects of a TN-S system are largely made void.
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By Stefan Fassbinder / Published on Mon, 2007-05-21 20:09
Have you ever come across a virtual protective earth? This is one of the weird occurrences due to skimping on copper. It may be a harmless idea to use a class I connector on a class II device and just miss out the PE contact, but to fit it with a cable that appears to have a protective earth conductor and has not is just hazardous because this cable might just as well be used on some Class I equipment! The VDE mark on the plug, of course, is a counterfeit. Found on a German-made, high-end, high-priced audio device (active loudspeaker).
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By Angelo Baggini / Published on Thu, 2007-02-01 14:03
A short eBook, from Engineering Consulting & Design to introduce the subject of power quality phenomena, the problems they cause and their solutions.
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