Electrical installation guide 2013

2015 Electrical installation guide According to IEC international standards Electrical installation guide Make the most of your energy Schneider Electric Industries SAS 35, rue Joseph Monier CS30323 F-92506 Rueil-Malmaison Cedex RCS Nanterre 954 503 439 Capital social 896 313 776 € www.schneider-electric.com EIGED306001EN ART.822690 As standards, specifications and designs change from time to time, please ask for confirmation of the information given in this pubication This document has been printed on ecological paper 01/2015 This guide has been written for electrical Engineers who have to design, select electrical equipment, install these equipment and, inspect or maintain low-voltage electrical installations in compliance with international Standards of the International Electrotechnical Commission (IEC) “Which technical solution will guarantee that all relevant safety rules are met?” This question has been a permanent guideline for the elaboration of this document An international Standard such as the IEC 60364 series “Low voltage Electrical Installations” specifies extensively the rules to comply with to ensure safety and correct operational functioning of all types of electrical installations As the Standard must be extensive, and has to be applicable to all types of equipment and the technical solutions in use worldwide, the text of the IEC rules is complex, and not presented in a ready-to-use order The Standard cannot therefore be considered as a working handbook, but only as a reference document The aim of the present guide is to provide a clear, practical and stepby-step explanation for the complete study of an electrical installation, according to IEC 60364 series and other relevant IEC Standards The first chapter (A) presents the methodology to be used, and refers to all chapters of the guide according to the different steps of the study We all hope that you, the reader, will find this handbook genuinely helpful Schneider Electric S.A This technical guide is the result of a collective effort Responsible for the coordination of this edition: Laurent MISCHLER The Electrical Installation Guide is a single document covering the techniques and standards related to low-voltage electrical installations It is intended for electrical professionals in companies, design offices, inspection organisations, etc Edition: 2015 This Technical Guide is aimed at professional users and is only intended to provide them guidelines for the definition of an industrial, tertiary or domestic electrical installation Information and guidelines contained in this Guide are provided AS IS Schneider Electric makes no warranty of any kind, whether express or implied, such as but not limited to the warranties of merchantability and fitness for a particular purpose, nor assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed in this Guide, nor represents that its use would not infringe privately owned rights The purpose of this guide is to facilitate the implementation of International installation standards for designers & contractors, but in all cases the original text of International or local standards in force shall prevail Price: 60 � ISBN: 978.2.9531643.3.6 N° dépôt légal: 1er semestre 2008 © Schneider Electric All rights reserved in all countries This new edition has been published to take into account changes in techniques, standards and regulations, in particular electrical installation standard IEC 60364 series We thank all the readers of the previous edition of this guide for their comments that have helped improve the current edition We also thank the many people and organisations, too numerous to name here, who have contributed in one way or another to the preparation of this guide Acknowlegements This guide has been realized by a team of experienced international experts, on the base of IEC 60364 series of standard, and include the latest developments in electrical standardization We shall mention particularly the following experts and their area of expertise: Chapter Christian Collombet Bernard Jover Jacques Schonek D, G R D, G, L, M, N Didier Fulchiron B Jean-Marc Biasse B Didier Mignardot J, P Eric Bettega E Pascal Lepretre E Emmanuel Genevray E, P Eric Breuillé Didier Segura F Fleur Janet K Franck Mégret G Geoffroy De-Labrouhe K F Jean Marc Lupin L, M Daniel Barstz N Hervé Lambert N, A Jérome Lecomte H Matthieu Guillot Jean-François Rey F, H, P F Tools for more efficiency in electrical installation design Electrical installation Wiki The Electrical Installation Guide is also available on-line as a wiki in languages: English > in English > in Russian > in Chinese > in German electrical-installation.org ru.electrical-installation.org cn.electrical-installation.org de.electrical-installation.org Our experts constantly contribute to its evolution Industry and academic professionals can collaborate too! Russian Chinese German Power Management Blog In the Schneider Electric blog, you will find the best tips about standards, tools, software, safety and latest technical news shared by our experts You will find even more information about innovations and business opportunities This is your place to leave us your comments and to engage discussion about your expertise You might want to sharewith your Twitter or LinkedIn followers > blog.schneider-electric.com/power-management-metering-monitoring-power-quality Schneider Electric - Electrical installation guide 2015 Online Electrical calculation Tools Online tools A set of tools designed to help you: ppdisplay on one chart the time-current cuves of different circuit-breakers or fuses ppcheck the discrimination between two circuit-breakers or fuses, or two Residual Current devices (RCD), search all the circuit-breakers or fuses that can be selective/cascading with a defined circuit-breaker or fuse ppcalculate the Cross Section Area of cables and build a cable schedule ppcalculate the voltage drop of a defined cable and check the maximum length > hto.power.schneider-electric.com Ecodial Advanced Calculation The new Ecodial Advanced Calculation software is dedicated to electrical installation calculation in accordance with IEC60364 international standard or national standards This 4th generation offers new features like: ppmanagement of operating mode (parallel transformers, back-up generators…) ppdiscrimination analysis associating curves checking and discrimination tables, direct access to protection settings Schneider Electric - Electrical installation guide 2015 Electrical installation guide 2015 Foreword Etienne TISON, International Electrotechnical Commission (IEC) TC64 Chairman The task of the IEC Technical Committee 64 is to develop and keep up-todate requirements - for the protection of persons against electrical shock, and - for the design, verification and implementation of low voltage electrical installations Series of standard such as IEC 60364 developed by IEC TC64 is considered by the international community as the basis of the majority of national low-voltage wiring rules IEC 60364 series is mainly focussed on safety due the use of electricity by people who may not be aware of risk resulting from the use of electricity But modern electrical installations are increasingly complex, due to external input such as - electromagnetic disturbances - energy efficiency - Consequently, designers, installers and consumers need guidance on the selection and installation of electrical equipment Schneider Electric has developed this Electrical Installation Guide dedicated to low voltage electrical installations It is based on IEC TC64 standards such as IEC 60364 series and provides additional information in order to help designers, contractors and controllers for implementing correct low-voltage electrical installations As TC64 Chairman, it is my great pleasure and honour to introduce this guide I am sure it will be used fruitfully by all persons involved in the implementation of all low-voltage electrical installations Etienne TISON has been working with Schneider Electric since 1978 He has been always involved is various activities in low voltage field In 2008, Etienne TISON has been appointed Chairman of IEC TC64 as well as Chairman of CENELEC TC64 Etienne TISON General rules of electrical installation design A Connection to the MV utility distribution network B Connection to the LV utility distribution network C MV & LV architecture selection guide for buildings D LV Distribution E Protection against electric shocks and electric fires F Sizing and protection of conductors G LV switchgear: functions & selection H Overvoltage protection J Energy efficiency in electrical distribution K Power Factor Correction L Harmonic management M Characteristics of particular sources and loads N Photovoltaic installations P Residential and other special locations Q EMC guidelines R General contents A B General rules of electrical installation design Methodology Rules and statutory regulations Installed power loads - Characteristics Power loading of an installation A2 A5 A11 A17 Connection to the MV utility distribution network Power supply at medium voltage Procedure for the establishment of a new substation Protection against electrical hazards, faults and miss operations in electrical installations The consumer substation with LV metering The consumer substation with MV metering Choice and use of MV equipment and MV/LV transformer B2 B10 B12 B23 B26 B29 Substation including generators and parallel operation of transformers B38 Types and constitution of MV/LV distribution substations C D B41 Connection to the LV utility distribution network Low-voltage utility distribution networks Tariffs and metering C2 C16 MV & LV architecture selection guide for buildings Stakes of architecture design Simplified architecture design process Electrical installation characteristics Technological characteristics Architecture assessment criteria Choice of architecture fundamentals Choice of architecture details Choice of equiment Recommendations for architecture optimization 10 Glossary 11 Example: electrical installation in a printworks E LV Distribution F Protection against electric shocks and electric fire G Sizing and protection of conductors Earthing schemes The installation system External influences General Protection against direct contact Protection against indirect contact Protection of goods due to insulation fault Implementation of the TT system Implementation of the TN system Implementation of the IT system Residual current devices RCDs Arc Fault Detection Devices (AFDD) D3 D4 D7 D11 D12 D14 D18 D25 D26 D30 D31 E2 E15 E34 F2 F4 F6 F17 F19 F23 F29 F36 F43 General Practical method for determining the smallest allowable cross-sectional area of circuit conductors Determination of voltage drop Short-circuit current Particular cases of short-circuit current Protective earthing conductor (PE) The neutral conductor G2 G7 Worked example of cable calculation G45 Schneider Electric - Electrical installation guide 2015 G19 G23 G29 G36 G41 General contents H LV switchgear: functions & selection The basic functions of LV switchgear The switchgear Choice of switchgear Circuit breaker H2 H5 H10 H11 Maintenance of low voltage switchgear H32 J Overvoltage protection K Energy Efficiency in electrical distribution L Power Factor Correction M Overvoltage of atmospheric origin Principle of lightning protection Design of the electrical installation protection system Installation of SPDs Application Technical supplements Energy Efficiency in brief Energy efficiency and electricity Diagnosis through electrical measurement Energy saving opportunities How to evaluate energy savings Power factor and Reactive power Why to improve the power factor? How to improve the power factor? Where to install power correction capacitors? How to determine the optimum level of compensation? Compensation at the terminals of a transformer Power factor correction of induction motors Example of an installation before and after power-factor correction The effects of harmonics 10 Implementation of capacitor banks J2 J7 J13 J24 J28 J32 K2 K3 K6 K8 K23 L2 L6 L8 L11 L13 L16 L19 L21 L22 L26 Harmonic management The problem: why is it necessary to manage harmonics? Definition and origin of harmonics Essential indicators of harmonic distortion and measurement principles Harmonic measurement in electrical networks Main effects of hamronis in electrical installations Standards Solutions to mitigate harmonics N Characteristics of particular sources and loads P Photovoltaic installations 5 Protection of a LV generator set and the downstream circuits Uninterruptible Power Supply Units (UPS) Protection of LV/LV transformers Lighting circuits Asynchronous motors Benefits of photovoltaic energy Background and technology PV System and Installation Rules PV installation architectures Monitoring Schneider Electric - Electrical installation guide 2015 M2 M3 M7 M10 M13 M20 M21 N2 N11 N24 N27 N55 P2 P3 P10 P18 P31 General contents Q Residential and other special locations R EMC guidelines Residential and similar premises Bathrooms and showers Recommendations applicable to special installations and locations Electrical distribution Earthing principles and structures Implementation Coupling mechanisms and counter-measures Wiring recommendations Schneider Electric - Electrical installation guide 2015 Q2 Q8 Q12 R2 R3 R5 R20 R26 R - EMC guidelines Fig R22: Some examples of washers, bolt and lugs mounting PE EMC LF - HF Painted sheet metal Ensure metal-to-metal contact Long PE paint HF paint HF L < 10 cm Fig R23: Earthing and bonding examples All the cables shall be laid on the grounded/earthed metallic structures All EMC components (e.g EMI filter, EMC clamps) shall be fixed directly on the metallic plates without any insulating coating (e.g free of paint or varnish) © Schneider Electric - all rights reserved R16 Schneider Electric - Electrical installation guide 2015 Implementation Screened cables coming or going out from the cubicle shall be bonded to the earthing bar or grounding plate if these cables are coming from long distance and/or from non equipotential zones The goal is to divert the disturbing currents at the cabinet entrance and not inside the cabinet Non metallic cabinet are not recommended for EMC purposes To protect electronics equipment against low frequency magnetic field, it is recommended to use (galvanized) steel cabinets Non magnetic metals (e.g aluminum, stainless steel) are more efficient for high frequencies environment Power and low level apparatus shall be physically separated and cables segregation and distances between power and sensitive cables shall also be respected as shown on the figures below LOW level Partition panel Power To power components Mains Actuators Probes Detectors Fig R24: Correct EMC design inside a same cabinet © Schneider Electric - all rights reserved R17 Schneider Electric - Electrical installation guide 2015 R - EMC guidelines LOW level Power Metal cable trough Fig R25: Correct EMC design inside two separate cabinets 3.11 Standards It is absolutely essential to specify the standards and recommendations that must be taken into account for installations Below are several documents that may be used: b EN 50174-1 Information technology - Cabling installation Part 1: Specification and quality assurance b EN 50174-2 Information technology - Cabling installation Part 2: Installation planning and practices inside buildings b EN 50310 Application of equipotential bonding and earthing in buildings with information technology equipment b EN 50173 Information Technology - Generic cabling systems b HD 60364-4-444 Low-voltage electrical installations Part 4-444: Protection for safety - Protection against voltage disturbances and electromagnetic disturbances 3.12 Electrostatic discharge protection Normally, the use of specific tools or packages is required to handle or carry electronics boards or components (CPU, memory, analog, PCMCIA modules, etc.) which are sensitive to Electrostatic discharge (ESD) R18 Our products comply with standard ESD tests but ESD conditions are in some cases over the specs © Schneider Electric - all rights reserved ESD threat could cause semiconductors aging and failures Without any care, the semiconductor devices could be damaged or burned without users noticing Solution The use of specific anti ESD wrist strap is highly recommended This wrist strap shall be installed inside each cabinet and correctly connected to the earthed cabinet metallic frame Schneider Electric - Electrical installation guide 2015 Implementation Provide a procedure which depicts the good conditions of use An example is shown below ESD Wrist Strap Static is produced by the contact and separation of materials: Shoes and floors, clothes and the human body, parts being moved on or from surfaces The generated charge will reside on the body until it is discharged - the familiar "zap" that all of us have experienced It's the "zap" that does the damage If we can prevent any static charge from building up on the body, then there is essentially nothing to be discharged A properly grounded wrist strap effectively prevents any static charge from building up Any static charge that would tend to be created is instantly "drained" by the wirst strap The wrist strap maintains the potential equilibrium that is accomplished the hard way with the "zap" Fig R26: ESD wrist strap examples © Schneider Electric - all rights reserved R19 Schneider Electric - Electrical installation guide 2015 R - EMC guidelines Coupling mechanisms and counter-measures 4.1 General An EM interference phenomenon may be summed up in Figure R27 below Source Coupling Victim Origin of emitted disturbances Means by which disturbances are transmitted Equipment likely to be disturbed Example: Radiated waves Walkie-talkie TV set Fig R27: EM interference phenomenon The different sources of disturbances are: b Radio-frequency emissions v Wireless communication systems (radio, TV, CB, radio telephones, remote controls) v Radar b Electrical equipment v High-power industrial equipment (induction furnaces, welding machines, stator control systems) v Office equipment (computers and electronic circuits, photocopy machines, large monitors) v Discharge lamps (neon, fluorescent, flash, etc.) v Electromechanical components (relays, contactors, solenoids, current interruption devices) b Power systems v Power transmission and distribution systems v Electrical transportation systems b Lightning b Electrostatic discharges (ESD) b Electromagnetic nuclear pulses (EMNP) The potential victims are: b Radio and television receivers, radar, wireless communication systems b Analogue systems (sensors, measurement acquisition, amplifiers, monitors) b Digital systems (computers, computer communications, peripheral equipment) © Schneider Electric - all rights reserved R20 R20 The different types of coupling are: b Common-mode impedance (galvanic) coupling b Capacitive coupling b Inductive coupling b Radiated coupling (cable to cable, field to cable, antenna to antenna) Schneider Electric - Electrical installation guide 2015 4 Coupling Coupling mechanisms mechanisms and and counter-measures counter-measures 4.2 4.2 Common-mode Common-mode impedance impedance coupling coupling Definition Definition Two or more more devices devices are are interconnected interconnected by by the the power power supply supply and and communication communication Two or cables (see Fig Fig R28) Ap19 When ) When external currents (lightning, fault currents, external currents (lightning, fault currents, disturbances) disturbances) via these common-mode impedances, undesirable voltage flow via these flow common-mode impedances, an undesirablean voltage appears between appears points A supposed and B which supposed to be equipotential This stray voltage can points A between and B which are to are be equipotential This stray voltageorcan low-level or fast electronic circuits disturb low-level fastdisturb electronic circuits All cables, including the protective conductors, have have an an impedance, impedance, particularly particularly at high frequencies Device Device11 Stray Stray overvoltage overvoltage Device Device2 ZZsign sign I2I2 A B ECPs ECPs Signal line Signal line ECPs ECPs I1 I1 Z1 Z1 Z2 Z2 The conductive parts parts (ECP) (ECP) of of devices devices 1 and and 2 are are connected connected to to a a common common The exposed exposed conductive earthing earthing terminal terminal via via connections connections with with impedances impedances Z1 Z1 and and Z2 Z2 The overvoltage flows flows to to the the earth earth via via Z1 Z1 The The potential potential of of device device 11 increases increases The stray stray overvoltage The difference difference in in potential potential with with device device 22 (initial (initial potential potential == 0) 0) results results in in the the to to Z1 Z1 II1 The appearance of current current II2 appearance of Z1 I = (Zsign + Z2) I ⇒ Z1 I2 = I (Zsign + Z2) Current I2, present on the signal line, disturbs device Fig Ap19Definition : Definition common-mode impedance coupling Fig R28: of of common-mode impedance coupling Examples Examples (see (see Fig Fig Ap20 R29) ) c linked by by a a common common reference reference conductor conductor (e.g (e.g PEN, PEN, PE) PE) affected affected by by fast fast b Devices Devices linked or (fault current, current, lightning lightning strike, strike, short-circuit, short-circuit, load load or intense intense (di/dt) (di/dt) current current variations variations (fault changes, chopping circuits, circuits, harmonic harmonic currents, power factor factor correction correction capacitor capacitor changes, chopping currents, power banks, etc.) banks, etc.) c of electrical electrical sources bA A common common return return path path for for a a number number of sources Ap15 Disturbed Disturbed cable cable Device Device Signal cable Signal cable Disturbing Disturbing current current Difference in Difference potential in potential ZMC ZMC Fig Ap20Example : Example common-mode impedance coupling Fig R29: of of common-mode impedance coupling Schneider Electric Electric Electrical Schneider Electrical installation installation guide guide 2005 2015 Fault Fault currents currents Lightning Lightning strike strike R21 © Schneider Electric - all rights reserved Device Device R - EMC guidelines Counter-measures (see Fig R30) If they cannot be eliminated, common-mode impedances must at least be as low as possible To reduce the effects of common-mode impedances, it is necessary to: b Reduce impedances: v Mesh the common references, v Use short cables or flat braids which, for equal sizes, have a lower impedance than round cables, v Install functional equipotential bonding between devices b Reduce the level of the disturbing currents by adding common-mode filtering and differential-mode inductors Device Z sign Stray overvoltage Device I2 Z sup Z1 PEC I1 Z2 If the impedance of the parallel earthing conductor PEC (Z sup) is very low compared to Z sign, most of the disturbing current flows via the PEC, i.e not via the signal line as in the previous case The difference in potential between devices and becomes very low and the disturbance acceptable Fig R30: Counter-measures of common-mode impedance coupling 4.3 Capacitive coupling U Vsource Definition The level of disturbance depends on the voltage variations (dv/dt) and the value of the coupling capacitance between the disturber and the victim t Vvictim © Schneider Electric - all rights reserved R22 R22 t Capacitive coupling increases with: b The frequency b The proximity of the disturber to the victim and the length of the parallel cables b The height of the cables with respect to a ground referencing plane b The input impedance of the victim circuit (circuits with a high input impedance are more vulnerable) b The insulation of the victim cable (εr of the cable insulation), particularly for tightly coupled pairs Figure R31 shows the results of capacitive coupling (cross-talk) between two cables Examples (see Fig R32 opposite page) Fig R31: Typical result of capacitive coupling (capacitive cross-talk) b Nearby cables subjected to rapid voltage variations (dv/dt) b Start-up of fluorescent lamps b High-voltage switch-mode power supplies (photocopy machines, etc.) b Coupling capacitance between the primary and secondary windings of transformers b Cross-talk between cables Schneider Electric - Electrical installation guide 2015 Coupling mechanisms and counter-measures Differential mode Common mode Source Vs DM Iv Victim Vs Iv CM CM DM Source Victim Vs DM: Source of the disturbing voltage (differential mode) Iv DM: Disturbing current on victim side (differential mode) Vs CM: Source of the disturbing voltage (common mode) Iv CM: Disturbing current on victim side (common mode) Metal shielding Fig R32: Example of capacitive coupling Counter-measures (see Fig R33) C Victim Fig R33: Cable shielding with perforations reduces capacitive coupling 4.4 Inductive coupling Definition The disturber and the victim are coupled by a magnetic field The level of disturbance depends on the current variations (di/dt) and the mutual coupling inductance Inductive coupling increases with: b The frequency b The proximity of the disturber to the victim and the length of the parallel cables, b The height of the cables with respect to a ground referencing plane, b The load impedance of the disturbing circuit Examples (see Fig R34 next page) b Nearby cables subjected to rapid current variations (di/dt) b Short-circuits b Fault currents b Lightning strikes b Stator control systems b Welding machines b Inductors Schneider Electric - Electrical installation guide 2015 R23 © Schneider Electric - all rights reserved Source b Limit the length of parallel runs of disturbers and victims to the strict minimum b Increase the distance between the disturber and the victim b For two-wire connections, run the two wires as close together as possible b Position a PEC bonded at both ends and between the disturber and the victim b Use two or four-wire cables rather than individual conductors b Use symmetrical transmission systems on correctly implemented, symmetrical wiring systems b Shield the disturbing cables, the victim cables or both (the shielding must be bonded) b Reduce the dv/dt of the disturber by increasing the signal rise time where possible R - EMC guidelines Disturbing cable Disturbing cable H H Victim loop Victim pair i i Victim loop Differential mode Common mode Fig R34: Example of inductive coupling Counter-measures b Limit the length of parallel runs of disturbers and victims to the strict minimum b Increase the distance between the disturber and the victim b For two-wire connections, run the two wires as close together as possible b Use multi-core or touching single-core cables, preferably in a triangular layout b Position a PEC bonded at both ends and between the disturber and the victim b Use symmetrical transmission systems on correctly implemented, symmetrical wiring systems b Shield the disturbing cables, the victim cables or both (the shielding must be bonded) b Reduce the dv/dt of the disturber by increasing the signal rise time where possible (series-connected resistors or PTC resistors on the disturbing cable, ferrite rings on the disturbing and/or victim cable) 4.5 Radiated coupling Definition The disturber and the victim are coupled by a medium (e.g air) The level of disturbance depends on the power of the radiating source and the effectiveness of the emitting and receiving antenna An electromagnetic field comprises both an electrical field and a magnetic field The two fields are correlated It is possible to analyse separately the electrical and magnetic components The electrical field (E field) and the magnetic field (H field) are coupled in wiring systems via the wires and loops (see Fig R35) E field H field i V © Schneider Electric - all rights reserved R24 R24 Field-to-cable coupling Fig R35: Definition of radiated coupling Schneider Electric - Electrical installation guide 2015 Field-to-loop coupling Coupling mechanisms and counter-measures When a cable is subjected to a variable electrical field, a current is generated in the cable This phenomenon is called field-to-cable coupling Similarly, when a variable magnetic field flows through a loop, it creates a counter electromotive force that produces a voltage between the two ends of the loop This phenomenon is called field-to-loop coupling Examples (see Fig R36) b Radio-transmission equipment (walkie-talkies, radio and TV transmitters, mobile services) b Radar b Automobile ignition systems b Arc-welding machines b Induction furnaces b Power switching systems b Electrostatic discharges (ESD) b Lighting E field EM field Signal cable Device Device i Device h h Area of the earth loop Ground reference plane Example of field-to-cable coupling Example of field-to-loop coupling Fig R36: Examples of radiated coupling Counter-measures To minimise the effects of radiated coupling, the measures below are required For field-to-cable coupling b Reduce the antenna effect of the victim by reducing the height (h) of the cable with respect to the ground referencing plane b Place the cable in an uninterrupted, bonded metal cableway (tube, trunking, cable tray) b Use shielded cables that are correctly installed and bonded b Add PECs b Place filters or ferrite rings on the victim cable For field-to-loop coupling b Reduce the surface of the victim loop by reducing the height (h) and the length of the cable Use the solutions for field-to-cable coupling Use the Faraday cage principle Radiated coupling decreases with the distance and when symmetrical transmission links are used Schneider Electric - Electrical installation guide 2015 R25 © Schneider Electric - all rights reserved Radiated coupling can be eliminated using the Faraday cage principle A possible solution is a shielded cable with both ends of the shielding connected to the metal case of the device The exposed conductive parts must be bonded to enhance effectiveness at high frequencies Wiring recommendations R - EMC guidelines 5.1 Signal classes (see Fig R37) Unshielded cables of different groups - Power connections (supply + PE) Shielded cables of different groups - Relay connections Device e h NO! Ground reference plane YES! - Analogue link (sensor) - Digital link (bus) Risk of cross-talk in common mode if e < h Sensitive cable Sensitive cable Disturbing cable Disturbing cable b Class Relay contacts This class is not very sensitive, but disturbs the other classes (switching, arcs when contacts open) YES! Fig R38: Wiring recommendations for cables carrying different types of signals NO! Fig R37: Internal signals can be grouped in four classes Four classes of internal signals are: b Class Mains power lines, power circuits with a high di/dt, switch-mode converters, powerregulation control devices This class is not very sensitive, but disturbs the other classes (particularly in common mode) u1m 30 cm NO! Cross incompatible cables at right angles b Class Digital circuits (HF switching) This class is sensitive to pulses, but also disturbs the following class b Class Analogue input/output circuits (low-level measurements, active sensor supply circuits) This class is sensitive YES! It is a good idea to use conductors with a specific colour for each class to facilitate identification and separate the classes This is useful during design and troubleshooting Standard cable Two distinct pairs 5.2 Wiring recommendations Poorly implemented ribbon cable Correctly implemented ribbon cable Digital connection Analogue pair Bonding wires Fig R39 : Use of cables and ribbon cable Disturbing cables (classes and 2) must be placed at some distance from the sensitive cables (classes and 4) (see Fig R38 and Fig R39) In general, a 10 cm separation between cables laid flat on sheet metal is sufficient (for both common and differential modes) If there is enough space, a distance of 30 cm is preferable If cables must be crossed, this should be done at right angles to avoid cross-talk (even if they touch) There are no distance requirements if the cables are separated by a metal partition that is equipotential with respect to the ECPs However, the height of the partition must be greater than the diameter of the cables © Schneider Electric - all rights reserved R26 Cables carrying different types of signals must be physically separated (see Fig R38 above) Schneider Electric - Electrical installation guide 2015 Wiring recommendations A cable should carry the signals of a single group (see Fig R40) If it is necessary to use a cable to carry the signals of different groups, internal shielding is necessary to limit cross-talk (differential mode) The shielding, preferably braided, must be bonded at each end for groups 1, and It is advised to overshield disturbing and sensitive cables (see Fig R41) The overshielding acts as a HF protection (common and differential modes) if it is bonded at each end using a circumferential connector, a collar or a clampere However, a simple bonding wire is not sufficient NO! Shielded pair Electronic control device Sensor Unshielded cable for stator control Electromechanical device YES! Bonded using a clamp Shielded pair + overshielding Electronic control device Sensor Shielded cable for stator control Electromechanical device Fig R41: Shielding and overshielding for disturbing and/or sensitive cables NO! Power + analogue Digital + relay contacts YES! Power + relay contacts Digital + analogue Avoid using a single connector for different groups (see Fig R42) Except where necessary for groups and (differential mode) If a single connector is used for both analogue and digital signals, the two groups must be separated by at least one set of contacts connected to 0 V used as a barrier All free conductors (reserve) must always be bonded at each end (see Fig R43) For group 4, these connections are not advised for lines with very low voltage and frequency levels (risk of creating signal noise, by magnetic induction, at the transmission frequencies) Shielding Power connections Digital connections Relay I/O connections Analogue connections Fig R40: Incompatible signals = different cables NO! YES! Electronic system NO! Electronic system YES! Wires not equipotentially bonded R27 Digital connections Fig R42: Segregation applies to connectors as well! Equipotential sheet metal panel Fig R43: Free wires must be equipotentially bonded Schneider Electric - Electrical installation guide 2015 Equipotential sheet metal panel © Schneider Electric - all rights reserved Analogue connections Wiring recommendations R - EMC guidelines The two conductors must be installed as close together as possible (see Fig R44) This is particularly important for low-level sensors Even for relay signals with a common, the active conductors should be accompanied by at least one common conductor per bundle For analogue and digital signals, twisted pairs are a minimum requirement A twisted pair (differential mode) guarantees that the two wires remain together along their entire length NO! Area of loop too large PCB with relay contact I/Os YES! PCB with relay contact I/Os + Power supply + Power supply Fig R44: The two wires of a pair must always be run close together Group-1 cables not need to be shielded if they are filtered But they should be made of twisted pairs to ensure compliance with the previous section Cables must always be positioned along their entire length against the bonded metal parts of devices (see Fig R45) For example: Covers, metal trunking, structure, etc In order to take advantage of the dependable, inexpensive and significant reduction effect (common mode) and anticross-talk effect (differential mode) NO! YES! Chassis Chassis Chassis Chassis Chassis Chassis YES! Metal tray Power supply R28 NO! Power or disturbing cables Relay cables I/O interface Power supply I/O interface All metal parts (frame, structure, enclosures, etc.) are equipotential Fig R45: Run wires along their entire length against the bonded metal parts © Schneider Electric - all rights reserved Measurement or sensitive cables Fig R46: Cable distribution in cable trays The use of correctly bonded metal trunking considerably improves internal EMC (see Fig R46) Schneider Electric - Electrical installation guide 2015 Schneider Electric - Electrical installation guide 2015 2015 Electrical installation guide According to IEC international standards Electrical installation guide Make the most of your energy Schneider Electric Industries SAS 35, rue Joseph Monier CS30323 F-92506 Rueil-Malmaison Cedex RCS Nanterre 954 503 439 Capital social 896 313 776 € www.schneider-electric.com EIGED306001EN ART.822690 As standards, specifications and designs change from time to time, please ask for confirmation of the information given in this pubication This document has been printed on ecological paper 01/2015 ... English > in Russian > in Chinese > in German electrical- installation. org ru .electrical- installation. org cn .electrical- installation. org de .electrical- installation. org Our experts constantly contribute... Jean-François Rey F, H, P F Tools for more efficiency in electrical installation design Electrical installation Wiki The Electrical Installation Guide is also available on-line as a wiki in languages:... guidance on the selection and installation of electrical equipment Schneider Electric has developed this Electrical Installation Guide dedicated to low voltage electrical installations It is based