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  01 Ръководство за електрически уредби глава А - Основни правила за проектиране на електрически уредби
       01 Ръководство за електрически уредби глава А - Основни правила за проектиране на електрически уредби 601.0 KB
   
  02 Ръководство за електрически уредби глава B - Свързване към разпределителна мрежа средно напрежение
       02 Ръководство за електрически уредби глава B - Свързване към разпределителна мрежа средно напрежение 921.0 KB
   
  03 Ръководство за електрически уредби глава C - Включване към електроразпределителна мрежа ниско напрежение
       03 Ръководство за електрически уредби глава C - Включване към електроразпределителна мрежа ниско напрежение 767.0 KB
   
  04 Ръководство за електрически уредби глава D – СрН и НН
       04 Ръководство за електрически уредби глава D – СрН и НН 608.0 KB
   
  05 Ръководство за електрически уредби глава E – Електроразпределение НН
       05 Ръководство за електрически уредби глава E – Електроразпределение НН 1011.0 KB
   
  06 Ръководство за електрически уредби глава F – Защита срещу поражения от електрически ток
       06 Ръководство за електрически уредби глава F – Защита срещу поражения от електрически ток 1703.0 KB
   
  07 Ръководство за електрически уредби глава G – Оразмеряване и защита на проводници
       07 Ръководство за електрически уредби глава G – Оразмеряване и защита на проводници 1672.0 KB
   
  08 Ръководство за електрически уредби глава H – Комутационна апаратура НН: предназначение и избор
       08 Ръководство за електрически уредби глава H – Комутационна апаратура НН: предназначение и избор 1263.0 KB
   
  09 Ръководство за електрически уредби глава J - Защита от пренапрежения в електрически уредби НН
       09 Ръководство за електрически уредби глава J - Защита от пренапрежения в електрически уредби НН 1408.0 KB
   
  10 Ръководство за електрически уредби глава K – Енергийна ефективност при разпределение на електрическата енергия
       10 Ръководство за електрически уредби глава K – Енергийна ефективност при разпределение на електрическата енергия 1317.0 KB
   
  11 Ръководство за електрически уредби глава L - Подобряване фактора на мощността и филтрация на хармониците
       11 Ръководство за електрически уредби глава L - Подобряване фактора на мощността и филтрация на хармониците 986.0 KB
   
  12 Ръководство за електрически уредби глава М – Ограничаване въздействието на хармониците
       12 Ръководство за електрически уредби глава М – Ограничаване въздействието на хармониците 759.0 KB
   
  13 Ръководство за електрически уредби глава N – Характеристики на специфични захранващи източници и товари
       13 Ръководство за електрически уредби глава N – Характеристики на специфични захранващи източници и товари 1334.0 KB
   
  14 Ръководство за електрически уредби глава Р – Жилищни и други специални помещения
       14 Ръководство за електрически уредби глава Р – Жилищни и други специални помещения 750.0 KB
   
  15 Ръководство за електрически уредби глава Q – Препоръки за осигуряване на електромагнитна съвместимост
       15 Ръководство за електрически уредби глава Q – Препоръки за осигуряване на електромагнитна съвместимост 1044.0 KB
   
  CT 018 - Analysis of three-phase networks in disturbed operating conditions using symmetrical components  
summary
CT 018 - Analysis of three-phase networks in disturbed operating conditions using symmetrical components

The dimensioning of an installation and the equipment to be used, the settings for the protection devices, and the analysis of electrical phenomena often require calculation of the currents and voltages in electrical networks.
The purpose of this “Cahier Technique” is to set out a simple method of calculating all these parameters in three-phase networks subject to disturbance using the symmetrical components method, and to provide specific application examples.
CT 018 - Analysis of three-phase networks in disturbed operating conditions using symmetrical components 546.0 KB
 
  CT 038 - Fault arcs on busbar sets and switchboards  
summary
CT 038 - Fault arcs on busbar sets and switchboards

The probability of appearance of a fault arc on a set of busbars cannot be considered as non-existant. The behaviour and speed of arcs have been analysed by a high-speed photography system. It appears that the damage produced by the arc is inversely proportional to its speed and its freedom of movement. Switchboard manufacturers, contractors and operators must take all possible precautions to reduce the possibility of arcs occurring, and their consequences.
CT 038 - Fault arcs on busbar sets and switchboards 774.0 KB
 
  CT 083 - Extra losses caused in high current conductors by skin and proximity effects  
summary
CT 083 - Extra losses caused in high current conductors by skin and proximity effects

A century ago, Lord Kelvin showed that any rapid change of current intensity in a conductor modifies the current density in the various pans of this conductor. The author recalls the consequences of the skin and proximity effects in the case of electrical conductors designed for high currents.
More attention should be paid to these phenomena in the case of the designing of certain busbars since it is clear that this particularity, often neglected, leads to an overdimensioning of the conductors, higher energy losses and poor overall operational efficiency.
CT 083 - Extra losses caused in high current conductors by skin and proximity effects 362.0 KB
 
  CT 144 - Introduction to dependability design  
summary
CT 144 - Introduction to dependability design

Equipment failures, unavailability of a power supply, stoppage of automated equipment and accidents are quickly becoming unacceptable events, be it to the ordinary citizen or industrial manufacturers.
Dependability and its components: reliability, maintainability, availability and safety, have become a science that no designer can afford to ignore. This technical report presents the basic concepts and an explanation of its basic computational methods. Some examples and several numerical values are given to complement the formulas and references to the various computer tools usually applied in this field.
CT 144 - Introduction to dependability design 174.0 KB
 
  CT 149 - EMC: Electromagnetic compatibility  
summary
CT 149 - EMC: Electromagnetic compatibility

For all electrotechnical equipment, EMC must be considered right from the initial design phase and the various principles and rules carried on through to manufacture and installation.
This means that all those involved, from the engineers and architects that design a building to the technicians that wire the electrical cabinets, including the specialists that design the various building networks and the crews that install them, must be concerned with EMC - a discipline aimed at achieving the "peaceful" coexistence of equipment sensitive to electromagnetic disturbances alongside equipment emitting such disturbances.
This publication is a compilation of many years of acquired experience at Merlin Gerin and presents various disturbances encountered and provides some practical solutions.
CT 149 - EMC: Electromagnetic compatibility 572.0 KB
 
  CT 151 - Overvoltages and insulation coordination in MV and HV  
summary
CT 151 - Overvoltages and insulation coordination in MV and HV

Insulation coordination is a discipline aiming at achieving the best possible technico-economic compromise for protection of people and equipment against overvoltages, whether caused by the network or lightning, occurring on electrical installations.
It helps ensure a high degree of availability of electrical power.
Its value is doubled by the fact that it concerns high voltage networks. To control insulation coordination:
- the level of the possible overvoltages occurring on the network must be known;
- the right protective devices must be used when necessary;
- the correct overvoltage withstand level must be chosen for the various network components from among the insulating voltages satisfying the particular constraints.
The purpose of this "Cahier Technique" is to further knowledge of voltage disturbances, how they can be limited and the standards to ensure safe, optimised distribution of electrical power by means of insulation coordination. It deals mainly with MV and HV.
CT 151 - Overvoltages and insulation coordination in MV and HV 195.0 KB
 
  CT 152 - Harmonic disturbances in networks, and their treatment  
summary
CT 152 - Harmonic disturbances in networks, and their treatment

Electricity is generally distributed as three voltage waves forming a 3-phase sinusoidal system. One of the characteristics of such a system is its waveform, which must always remain as close as possible to that of a pure sine wave.
If distorted beyond certain limits, as is often the case on networks comprising sources of harmonic currents and voltages such as arc furnaces, static power converters, lighting systems, etc., the waveform must be corrected.

The aim of the present document is to provide a better understanding of these harmonics problems, including their causes and the most commonly used solutions.
CT 152 - Harmonic disturbances in networks, and their treatment 236.0 KB
 
  CT 158 - Calculation of short-circuit currents  
summary
CT 158 - Calculation of short-circuit currents

In view of sizing an electrical installation and the required equipment, as well as determining the means required for the protection of life and property, short-circuit currents must be calculated for every point in the network.
This “Cahier Technique” reviews the calculation methods for short-circuit currents as laid down by standards such as IEC 60909. It is intended for radial and meshed low voltage (LV) and high voltage (HV) circuits.
The aim is to provide a further understanding of the calculation methods, essential when determining short-circuit currents, even when computerised methods are employed.
CT 158 - Calculation of short-circuit currents 762.0 KB
 
  CT 161 - Automatic transfering of power supplies in HV and LV networks  
summary
CT 161 - Automatic transfering of power supplies in HV and LV networks

Nowadays even temporary loss of electrical power is a major handicap for firms whose production processes brook no interruption as well as for high-rise buildings whose safety circuits must be operational at all times.
Consequently, transferring of main supply sources onto replacement or emergency sources has proved to be a function used with increasing regularity in electrical distribution, public and private alike.
- This "Cahier Technique" begins with an examination of the difficulties of implementing such switching devices, together with the possible technical solutions.
- This section is followed by a presentation of the various switching types backed up by practical examples.
- Finally, a table summarises the above and gives the main areas of application.
CT 161 - Automatic transfering of power supplies in HV and LV networks 75.0 KB
 
  CT 166 - Enclosures and Degrees of Protection  
summary
CT 166 - Enclosures and Degrees of Protection

The protection of persons against direct contacts is required by certain regulations (in France the Decree of the 14th of November 1988), and specified by electrical installation standards, such as IEC 364. On the other hand, types of external stresses likely to influence the behaviour of equipment are described in IEC 721-2. The protection against some of these influences is often specified in product standards.
Therefore, to explain the degrees of protection that enclosures can provide, and how standards codify them, constitutes an essential information for all, prescribers, installers, operators and inspecting organisations and is the purpose of this "Cahier Technique". It replaces "Cahier Technique" No 6 written in 1982, made obsolete by the revision of IEC 529.
CT 166 - Enclosures and Degrees of Protection 75.0 KB
 
  CT 180 - Earthquakes and electrical equipment  
summary
CT 180 - Earthquakes and electrical equipment

In all countries there is either a zone of significant seismic activity or installations which require high security in order to operate (e.g. nuclear power stations, which generally have low seismic activity). In both cases the electrical and control and monitoring equipment must assure their safety functions correctly.
This technical paper aims to facilitate dialogue between operators and specialists. After briefly summarising the earthquake phenomena and the way in which they are specified, the author presents the theoretic approach required for seismic withstand capabilities to be taken into account at the design stage.
Today, both design and qualification increasingly require numerical analysis and, as a result, powerful scientific and technical data processing methods.
CT 180 - Earthquakes and electrical equipment 222.0 KB
 
  CT 183 - Active harmonic conditioners and unity power factor rectifiers  
summary
CT 183 - Active harmonic conditioners and unity power factor rectifiers

Electric loads are becoming increasingly non-linear in the industrial, tertiary and even household sectors. These loads absorb non-sinusoidal currents which, under the effect of circuit impedance, distort the purely sinusoidal voltage waveform. This is what is known as harmonic disturbance of power networks, currently a cause for concern as it gives rise to serious problems.
We recommend that harmonic non-specialist readers begin by reading the appendix where they will find the basic concepts required to understand the various standard and new solutions to limit or combat harmonics. Not only the characteristic quantities, but also the non linear equipment, influence of the sources and disturbing effects of harmonics need to be known. Last but not least, standards lay down levels of compatibility, i.e. the maximum permissible levels.
The purpose of this "Cahier Technique" is to describe the active harmonic conditioners. This attractive, flexible and self-adaptive solution can be used in a wide variety of cases to complete or replace other solutions.
However chapter 1 of this "Cahier Technique" will review other "traditional" solutions which should also be taken into consideration.
CT 183 - Active harmonic conditioners and unity power factor rectifiers 318.0 KB
 
  CT 184 - Electrical installation dependability studies  
summary
CT 184 - Electrical installation dependability studies

In both the industrial and tertiary sectors, the quality of power supply is of increasing importance. The quality of the electricity product, besides imperfections such as variations in voltage and harmonic distortion, is basically characterised by the availability of the electrical energy.
Loss of power is always annoying, but it can be particularly penalising for information systems (computing -monitoring and control); they can even have disastrous consequences for certain processes and in certain cases endanger people's lives. Dependability studies enable electrical availability requirements to be incorporated in the choice of electrical network to be installed. They also enable two different installation configurations to be compared ... the most expensive one is not always better ...
The aim of this "Cahier Technique" is to show how dependability studies are performed: methodology and tools. Two examples of studies are given: that of an electrical network in a factory and that of the monitoring and control system of a high voltage substation. These studies are becoming increasingly easy to perform thanks to computing "tools".
CT 184 - Electrical installation dependability studies 123.0 KB
 
  CT 185 - Dynamic stability of industrial electrical networks  
summary
CT 185 - Dynamic stability of industrial electrical networks

Given that electrical energy is very difficult to store, a permanent balance between production and consumption is vital. Generators, loads and the electrical networks which connect them have mechanical and/or electrical inertias which complicate the maintaining of a balance guararanteeing relatively constant frequency and voltage.
When confronted with a power variation, the electrical system normally resumes a stable state after a few oscillations. However in certain cases the oscillating state can diverge, and studies are then required to avoid this phenomenon and guarantee the stability of the electrical network. These studies are of particular importance in the case of industrial networks which contain one or more generator sets and motors.
The purpose of this "Cahier Technique" is to understand why instability can appear and to define the main causes and effects of such instability. It explains the precautions to be taken and, using a concrete example, describes how a typical study is conducted.
CT 185 - Dynamic stability of industrial electrical networks 130.0 KB
 
  CT 187 - Cohabitation of high and low currents  
summary
CT 187 - Cohabitation of high and low currents

In our society today, the rapid development of digital systems using low current links (bus) has given rise to the critical problem formed by cohabitation of high and low currents.
The real problem is how to reconcile electrical safety and electromagnetic compatibility.
The following issues thus arise for which solutions must be found:
- how to treat the problem of exposed conductive parts,
- which earthing system should be chosen,
- which shields, mitigating planes, Faraday cages should be chosen and for what purpose,
- how to organise routing of high and low current circuits,
- and many others.
Although written with electrical engineers in mind, this "Cahier Technique" will certainly also be of interest to low current specialists since it mainly deals with low frequency disturbances of < 1 MHz.
CT 187 - Cohabitation of high and low currents 175.0 KB
 
  CT 190 - Ferroresonance  
summary
CT 190 - Ferroresonance

Ferroresonance is a non-linear resonance phenomenon that can affect power networks. The abnormal rates of harmonics and transient or steady state overvoltages and overcurrents that it causes are often dangerous for electrical equipment. Some unexplained breakdowns can be ascribed to this rare, non-linear phenomenon.
The purpose of this "Cahier Technique" is to help readers understand ferroresonance. The methods described ensure credible prediction and evaluation of the risk of ferroresonance in existing and future installations. Practical solutions designed to avoid or eliminate ferroresonance are also given.
CT 190 - Ferroresonance 177.0 KB
 
  CT 194 - Current Transformers: how to specify them  
summary
CT 194 - Current Transformers: how to specify them

Electrical power management requires implementation of data processing units able to monitor networks or equipment and, as applicable, to initiate the appropriate actions...
Data sent by current transformers are processed by protection, control and monitoring units that send signals to operate switchgear and/or information to a supervisory unit or to a central control room.
The task, consisting of identifying and rating the current transformers and associating them with the protection and/or metering units, has always given rise to problems, both for electrical engineers (oversizing the characteristics) and for the manufacturer (random feasibility, excessive sizing, high costs).
This document does not cover the technical demonstrations amply referred to in the literature (see "Cahiers Techniques" no.164 and 170). Its purpose is to remind users of a few simple rules enabling the best possible definition of the secondary characteristics of a current transformer (CT) according to the protections and applications concerned.
Practically, it offers constructive assistance for technicians who have reached a dead end:
- either because they do not possess the necessary information,
- or because the results of their design have led to current transformers that cannot be manufactured by the potential suppliers.
CT 194 - Current Transformers: how to specify them 371.0 KB
 
  CT 195 - Current Transformers: specification errors and solutions  
summary
CT 195 - Current Transformers: specification errors and solutions

After a reminder of current transformers (CTs), the author highlights the errors most often encountered when defining current transformers, an essential and little known link between the electrical network and the protection relays.
It explains how to find a way out of difficult situations: CTs that cannot be manufactured, delays, additional costs, malfunctions, etc.
This "Cahier Technique" should be useful for electricians designing installations, for protection specialists, panel builders and all CT manufacturers. It is in the best interest of all to exchange all information required for the safety and optimisation of CTs.
This Cahier Technique is an operational addition to Cahier Technique no.194 “Current Transformers: how to specify them”.
CT 195 - Current Transformers: specification errors and solutions 161.0 KB
 
  CT 196 - Integration of local power generation in industrial sites and commercial buildings  
summary
CT 196 - Integration of local power generation in industrial sites and commercial buildings

Engine driven alternating current generator sets are often used in remote industrial sites as a prime source of electrical energy.
They are also extensively used in both industry and commercial buildings as a source of back-up power.
This "Cahier Technique" discusses most of the subjects which have to be handled when implementing engine driven alternating current generator sets having rated powers up to 20 MW.
CT 196 - Integration of local power generation in industrial sites and commercial buildings 574.0 KB
 
  CT 199 - Power Quality  
summary
CT 199 - Power Quality

One of the properties of electricity is that some of its characteristics depend not only on the electricity producer/distributor but also on the equipment manufacturers and the customer. The large number of players combined with the use of terminology and definitions which may sometimes be imprecise partly explain why this subject area is so complex.
This "Cahier Technique" aims to facilitate exchanges on this topic between specialists and non-specialists, as well as customers, manufacturers, installers, designers and distributors. The clear terminology used should help avoid confusion. It describes the main phenomena causing degradation in Power Quality (PQ), their origins, the consequences for equipment and the main solutions. It offers a methodology for measuring the PQ in accordance with differing aims. Illustrated with practical examples for the implementation of solutions, it shows that only by observing best practices and by applying strict methodology (diagnostics, research, solutions, implementation and preventive maintenance) can users obtain the right quality of power supply for their requirements.
CT 199 - Power Quality 879.0 KB
 
  CT 202 - The singularities of the third harmonic  
summary
CT 202 - The singularities of the third harmonic

In installations where the neutral is distributed, non-linear loads may cause significant overloads in this conductor due to the presence of the third harmonic.
Both the phenomenon and its solutions are explained in this "Cahier Technique".
CT 202 - The singularities of the third harmonic 186.0 KB
 
  CT 206 - Energy savings in buildings  
summary
CT 206 - Energy savings in buildings

Irrespective of the building to be built or managed, there is a need for solutions to control energy consumption. This holds true throughout the world for all types of buildings, in the industrial, residential or service sectors.
Before designing or upgrading a building, and in particular its electrical installations, it is essential: to study its energy needs and the available energy sources; to find the best balance between management systems, distribution networks and consumer equipment; to take account of operational requirements.
This “Cahier Technique” presents a methodology for effective preliminary study work. The author therefore explores all of the elements which contribute to energy savings and which, depending on the installation, may or may not be selected.
CT 206 - Energy savings in buildings 206.0 KB
 
  CT 207 - Electric motors ... and how to improve their control and protection  
summary
CT 207 - Electric motors ... and how to improve their control and protection

Nowadays, apart from lighting devices, electric motors represent the largest loads in industry and commercial installations. Their function, to convert electrical energy into mechanical energy, means they are particularly significant in economic terms, and hence, they cannot be ignored by installation or machinery designers, installers or users.
There are many types of motor in existence, but 3-phase asynchronous motors, and in particular squirrel cage motors, are the most commonly used in industry and in commercial building applications above a certain power level. Moreover, although they are ideal for many applications when controlled by contactor devices, the increasing use of electronic equipment is widening their field of application. This is the case for start/stop control with soft start/soft stop units, and when precise speed adjustment is also necessary with variable speed drives/regulators.
However, slip-ring asynchronous motors are used for certain high power applications in industry, and single phase asynchronous motors remain suitable for limited power applications, mainly for building applications.
The use of synchronous motors, known as brushless or permanent magnet motors, combined with converters is becoming increasingly common in applications requiring high performance levels, in particular in terms of dynamic torque (on starting or on a change of duty), precision and speed range.
After presenting the various types of electric motor and their operating principles, this "Cahier Technique" describes the technical and operating features of asynchronous motors, covering in particular the main starting devices, speed control and braking methods. It provides a solid grounding for the reader to gain a good understanding of all the problems involved with motor control and protection.
This "Cahier Technique" touches briefly on variable speed control of electric motors. However, this subject is covered more specifically in "Cahier Technique" CT 208 "Electronic starters and variable speed drives". Motor protection is the subject of another "Cahier Technique" currently in preparation.
CT 207 - Electric motors ... and how to improve their control and protection 398.0 KB
 
  CT 213 - Calculations for LV and HV networks  
summary
CT 213 - Calculations for LV and HV networks

This Cahier Technique publication is intended to provide a general overview of the main electrotechnical calculations carried out in engineering studies on electrical systems at all voltage levels.
It is complementary to other Cahier Technique publications that deal more with the operation of devices and installations in electrical systems. This document will help owners, designers and operators understand the importance of these calculations in ensuring correct use of the electrical network and their impact on the total cost of ownership.
CT 213 - Calculations for LV and HV networks 623.0 KB
 
  CT 214 - Energy efficiency: benefits of variable speed control in pumps, fans and compressors  
summary
CT 214 - Energy efficiency: benefits of variable speed control in pumps, fans and compressors

A large proportion of the electricity produced around the world is used to raise, move or pressurise liquids and gases with machines such as pumps, fans and compressors. Given the increasing importance of controlling energy consumption, special attention must be paid to the way these machines are operated and the energy savings that can be achieved through variable speed control. These different aspects will be dealt with in this Cahier Technique publication, both from the qualitative and quantitative standpoint. Variable speed drives are among the front-ranking solutions proposed by SchneiderElectric to increase Energy efficiency.
CT 214 - Energy efficiency: benefits of variable speed control in pumps, fans and compressors 906.0 KB