{"id":1547,"date":"2017-06-03T11:57:18","date_gmt":"2017-06-03T02:57:18","guid":{"rendered":"http:\/\/now0930.tk\/wordpress\/?p=1547"},"modified":"2017-06-14T00:41:16","modified_gmt":"2017-06-13T15:41:16","slug":"wiring-guide-common-mode-counter-measures","status":"publish","type":"post","link":"https:\/\/now0930.pe.kr\/wordpress\/wiring-guide-common-mode-counter-measures\/","title":{"rendered":"Wiring Guide, Common Mode and counter-measures"},"content":{"rendered":"<p>from <a href=\"http:\/\/www.electrical-installation.org\/enwiki\/Wiring_recommendations\">Shenider<\/a><\/p>\n<p>Signal classes<\/p>\n<p>(see <b>Fig.<\/b> <span class=\"FigRef\">R37<\/span>)<\/p>\n<div class=\"thumb tnone\">\n<div class=\"thumbinner\">\n<p><a class=\"image\" href=\"http:\/\/www.electrical-installation.org\/enw\/index.php?title=File:DB422805_EN.svg&amp;page=1\"><img loading=\"lazy\" decoding=\"async\" class=\"thumbimage\" src=\"http:\/\/www.electrical-installation.org\/enw\/images\/thumb\/7\/70\/DB422805_EN.svg\/458px-DB422805_EN.svg.png\" alt=\"\" width=\"458\" height=\"245\" \/><\/a><\/p>\n<div class=\"thumbcaption\">\n<p class=\"figure-title\"><i><b>Fig. R37<\/b><\/i>:\u00a0<i>Internal signals can be grouped in four classes<\/i><\/p>\n<\/div>\n<\/div>\n<\/div>\n<p>Four classes of internal signals are:<\/p>\n<ul>\n<li><b>Class 1<\/b><\/li>\n<\/ul>\n<dl>\n<dd>Mains power lines, power circuits with a high di\/dt, switch-mode converters, power-regulation control devices.<\/dd>\n<dd>This class is not very sensitive, but disturbs the other classes (particularly in common mode).<\/dd>\n<\/dl>\n<ul>\n<li><b>Class 2<\/b><\/li>\n<\/ul>\n<p>Relay contacts.<\/p>\n<dl>\n<dd>This class is not very sensitive, but disturbs the other classes (switching, arcs when contacts open).<\/dd>\n<\/dl>\n<ul>\n<li><b>Class 3<\/b><\/li>\n<\/ul>\n<dl>\n<dd>Digital circuits (HF switching).<\/dd>\n<dd>This class is sensitive to pulses, but also disturbs the following class.<\/dd>\n<\/dl>\n<ul>\n<li><b>Class 4<\/b><\/li>\n<\/ul>\n<dl>\n<dd>Analogue input\/output circuits (low-level measurements, active sensor supply circuits). This class is sensitive.<\/dd>\n<dd>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.<\/dd>\n<\/dl>\n<h2><span id=\"Wiring_recommendations\" class=\"mw-headline\"> Wiring recommendations <\/span><\/h2>\n<h3><span id=\"Cables_carrying_different_types_of_signals_must_be_physically_separated\" class=\"mw-headline\"> Cables carrying different types of signals must be physically separated <\/span><\/h3>\n<div class=\"thumb tnone\">\n<div class=\"thumbinner\">\n<p><a class=\"image\" href=\"http:\/\/www.electrical-installation.org\/enw\/index.php?title=File:DB422806_EN.svg&amp;page=1\"><img loading=\"lazy\" decoding=\"async\" class=\"thumbimage\" src=\"http:\/\/www.electrical-installation.org\/enw\/images\/thumb\/8\/83\/DB422806_EN.svg\/367px-DB422806_EN.svg.png\" alt=\"\" width=\"367\" height=\"474\" \/><\/a><\/p>\n<div class=\"thumbcaption\">\n<p class=\"figure-title\"><i><b>Fig. R38<\/b><\/i>:\u00a0<i>Wiring recommendations for cables carrying different types of signals<\/i><\/p>\n<\/div>\n<\/div>\n<\/div>\n<h3><span id=\"Disturbing_cables_.28classes_1_and_2.29_must_be_placed_at_some_distance_from_the_sensitive_cables_.28classes_3_and_4.29\" class=\"mw-headline\"> Disturbing cables (classes 1 and 2) must be placed at some distance from the sensitive cables (classes 3 and 4) <\/span><\/h3>\n<p>(see <b>Fig.<\/b> <span class=\"FigRef\">R38<\/span> and <b>Fig.<\/b> <span class=\"FigRef\">R39<\/span>)<\/p>\n<p>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.<\/p>\n<div class=\"thumb tnone\">\n<div class=\"thumbinner\">\n<p><a class=\"image\" href=\"http:\/\/www.electrical-installation.org\/enw\/index.php?title=File:DB422807_EN.svg&amp;page=1\"><img loading=\"lazy\" decoding=\"async\" class=\"thumbimage\" src=\"http:\/\/www.electrical-installation.org\/enw\/images\/thumb\/9\/97\/DB422807_EN.svg\/318px-DB422807_EN.svg.png\" alt=\"\" width=\"318\" height=\"269\" \/><\/a><\/p>\n<div class=\"thumbcaption\">\n<p class=\"figure-title\"><i><b>Fig. R39<\/b><\/i>:\u00a0<i>Use of cables and ribbon cable<\/i><\/p>\n<\/div>\n<\/div>\n<\/div>\n<h3><span id=\"A_cable_should_carry_the_signals_of_a_single_group\" class=\"mw-headline\"> A cable should carry the signals of a single group <\/span><\/h3>\n<p>(see <b>Fig.<\/b> <span class=\"FigRef\">R40<\/span>)<\/p>\n<p>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, 2 and 3.<\/p>\n<div class=\"thumb tnone\">\n<div class=\"thumbinner\">\n<p><a class=\"image\" href=\"http:\/\/www.electrical-installation.org\/enw\/index.php?title=File:DB422808_EN.svg&amp;page=1\"><img loading=\"lazy\" decoding=\"async\" class=\"thumbimage\" src=\"http:\/\/www.electrical-installation.org\/enw\/images\/thumb\/1\/16\/DB422808_EN.svg\/352px-DB422808_EN.svg.png\" alt=\"\" width=\"352\" height=\"224\" \/><\/a><\/p>\n<div class=\"thumbcaption\">\n<p class=\"figure-title\"><i><b>Fig. R40<\/b><\/i>:\u00a0<i>Incompatible signals = different cables<\/i><\/p>\n<\/div>\n<\/div>\n<\/div>\n<h3><span id=\"It_is_advised_to_overshield_disturbing_and_sensitive_cables\" class=\"mw-headline\"> It is advised to overshield disturbing and sensitive cables <\/span><\/h3>\n<p>(see <b>Fig.<\/b> <span class=\"FigRef\">R41<\/span>)<\/p>\n<p>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.<\/p>\n<div class=\"thumb tnone\">\n<div class=\"thumbinner\">\n<p><a class=\"image\" href=\"http:\/\/www.electrical-installation.org\/enw\/index.php?title=File:DB422809_EN.svg&amp;page=1\"><img loading=\"lazy\" decoding=\"async\" class=\"thumbimage\" src=\"http:\/\/www.electrical-installation.org\/enw\/images\/thumb\/f\/f5\/DB422809_EN.svg\/473px-DB422809_EN.svg.png\" alt=\"\" width=\"473\" height=\"340\" \/><\/a><\/p>\n<div class=\"thumbcaption\">\n<p class=\"figure-title\"><i><b>Fig. R41<\/b><\/i>:\u00a0<i>Shielding and overshielding for disturbing and\/or sensitive cables<\/i><\/p>\n<\/div>\n<\/div>\n<\/div>\n<h3><span id=\"Avoid_using_a_single_connector_for_different_groups\" class=\"mw-headline\"> Avoid using a single connector for different groups <\/span><\/h3>\n<p>(see <b>Fig.<\/b> <span class=\"FigRef\">R42<\/span>)<\/p>\n<p>Except where necessary for groups 1 and 2 (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.<\/p>\n<div class=\"thumb tnone\">\n<div class=\"thumbinner\">\n<p><a class=\"image\" href=\"http:\/\/www.electrical-installation.org\/enw\/index.php?title=File:DB422810_EN.svg&amp;page=1\"><img loading=\"lazy\" decoding=\"async\" class=\"thumbimage\" src=\"http:\/\/www.electrical-installation.org\/enw\/images\/thumb\/c\/cc\/DB422810_EN.svg\/307px-DB422810_EN.svg.png\" alt=\"\" width=\"307\" height=\"166\" \/><\/a><\/p>\n<div class=\"thumbcaption\">\n<p class=\"figure-title\"><i><b>Fig. R42<\/b><\/i>:\u00a0<i>Segregation applies to connectors as well!<\/i><\/p>\n<\/div>\n<\/div>\n<\/div>\n<h3><span id=\"All_free_conductors_.28reserve.29_must_always_be_bonded_at_each_end\" class=\"mw-headline\"> All free conductors (reserve) must always be bonded at each end <\/span><\/h3>\n<p>(see <b>Fig.<\/b> <span class=\"FigRef\">R43<\/span>)<\/p>\n<p>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).<\/p>\n<div class=\"thumb tnone\">\n<div class=\"thumbinner\">\n<p><a class=\"image\" href=\"http:\/\/www.electrical-installation.org\/enw\/index.php?title=File:DB422811_EN.svg&amp;page=1\"><img loading=\"lazy\" decoding=\"async\" class=\"thumbimage\" src=\"http:\/\/www.electrical-installation.org\/enw\/images\/thumb\/5\/5c\/DB422811_EN.svg\/465px-DB422811_EN.svg.png\" alt=\"\" width=\"465\" height=\"235\" \/><\/a><\/p>\n<div class=\"thumbcaption\">\n<p class=\"figure-title\"><i><b>Fig. R43<\/b><\/i>:\u00a0<i>Free wires must be equipotentially bonded<\/i><\/p>\n<\/div>\n<\/div>\n<\/div>\n<h3><span id=\"The_two_conductors_must_be_installed_as_close_together_as_possible\" class=\"mw-headline\"> The two conductors must be installed as close together as possible <\/span><\/h3>\n<p>(see <b>Fig.<\/b> <span class=\"FigRef\">R44<\/span>)<\/p>\n<p>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.<\/p>\n<div class=\"thumb tnone\">\n<div class=\"thumbinner\">\n<p><a class=\"image\" href=\"http:\/\/www.electrical-installation.org\/enw\/index.php?title=File:DB422812_EN.svg&amp;page=1\"><img loading=\"lazy\" decoding=\"async\" class=\"thumbimage\" src=\"http:\/\/www.electrical-installation.org\/enw\/images\/thumb\/3\/3f\/DB422812_EN.svg\/527px-DB422812_EN.svg.png\" alt=\"\" width=\"527\" height=\"284\" \/><\/a><\/p>\n<div class=\"thumbcaption\">\n<p class=\"figure-title\"><i><b>Fig. R44<\/b><\/i>:\u00a0<i>The two wires of a pair must always be run close together<\/i><\/p>\n<\/div>\n<\/div>\n<\/div>\n<h3><span id=\"Group-1_cables_do_not_need_to_be_shielded_if_they_are_filtered\" class=\"mw-headline\"> Group-1 cables do not need to be shielded if they are filtered <\/span><\/h3>\n<p>But they should be made of twisted pairs to ensure compliance with the previous section.<\/p>\n<h3><span id=\"Cables_must_always_be_positioned_along_their_entire_length_against_the_bonded_metal_parts_of_devices\" class=\"mw-headline\"> Cables must always be positioned along their entire length against the bonded metal parts of devices <\/span><\/h3>\n<p>(see <b>Fig.<\/b> <span class=\"FigRef\">R45<\/span>)<\/p>\n<p>For example: Covers, metal trunking, structure, etc. In order to take advantage of the dependable, inexpensive and significant reduction effect (common mode) and anti-cross-talk effect (differential mode).<\/p>\n<div class=\"thumb tnone\">\n<div class=\"thumbinner\">\n<p><a class=\"image\" href=\"http:\/\/www.electrical-installation.org\/enw\/index.php?title=File:DB422813_EN.svg&amp;page=1\"><img loading=\"lazy\" decoding=\"async\" class=\"thumbimage\" src=\"http:\/\/www.electrical-installation.org\/enw\/images\/thumb\/9\/94\/DB422813_EN.svg\/404px-DB422813_EN.svg.png\" alt=\"\" width=\"404\" height=\"274\" \/><\/a><\/p>\n<div class=\"thumbcaption\">\n<p class=\"figure-title\"><i><b>Fig. R45<\/b><\/i>:\u00a0<i>Run wires along their entire length against the bonded metal parts<\/i><\/p>\n<\/div>\n<\/div>\n<\/div>\n<h3><span id=\"The_use_of_correctly_bonded_metal_trunking_considerably_improves_internal_EMC\" class=\"mw-headline\"> The use of correctly bonded metal trunking considerably improves internal EMC <\/span><\/h3>\n<p>(see <b>Fig.<\/b> <span class=\"FigRef\">R46<\/span>)<\/p>\n<div class=\"thumb tnone\">\n<div class=\"thumbinner\">\n<p><a class=\"image\" href=\"http:\/\/www.electrical-installation.org\/enw\/index.php?title=File:DB422814_EN.svg&amp;page=1\"><img loading=\"lazy\" decoding=\"async\" class=\"thumbimage\" src=\"http:\/\/www.electrical-installation.org\/enw\/images\/thumb\/6\/6c\/DB422814_EN.svg\/283px-DB422814_EN.svg.png\" alt=\"\" width=\"283\" height=\"211\" \/><\/a><\/p>\n<div class=\"thumbcaption\">\n<p class=\"figure-title\"><i><b>Fig. R46<\/b><\/i>:\u00a0<i>Cable distribution in cable trays<\/i><\/p>\n<\/div>\n<h1 id=\"firstHeading\" class=\"firstHeading h1Befor\"><span dir=\"auto\">Common-mode impedance coupling<\/span><\/h1>\n<p>Definition<\/p>\n<p>Two or more devices are interconnected by the power supply and communication cables (see <b>Fig.<\/b> <span class=\"FigRef\">R28<\/span>). When external currents (lightning, fault currents, disturbances) flow via these common-mode impedances, an undesirable voltage appears between points A and B <b>which are supposed to be equipotential<\/b>. This stray voltage can disturb low-level or fast electronic circuits.<\/p>\n<p>All cables, including the protective conductors, have an impedance, particularly at high frequencies.<\/p>\n<div class=\"thumb tnone\">\n<div class=\"thumbinner\">\n<p><a class=\"image\" href=\"http:\/\/www.electrical-installation.org\/enw\/index.php?title=File:DB422796_EN.svg&amp;page=1\"><img loading=\"lazy\" decoding=\"async\" class=\"thumbimage\" src=\"http:\/\/www.electrical-installation.org\/enw\/images\/thumb\/4\/43\/DB422796_EN.svg\/486px-DB422796_EN.svg.png\" alt=\"\" width=\"486\" height=\"290\" \/><\/a><\/p>\n<div class=\"thumbcaption\">\n<p class=\"figure-notes\">The exposed conductive parts (ECP) of devices 1 and 2 are connected to a common earthing terminal via connections with impedances Z1 and Z2.<br \/>\nThe stray overvoltage flows to the earth via Z1. The potential of device 1 increases to Z1 I1. The difference in potential with device 2 (initial potential = 0) results in the appearance of current I2.<br \/>\n<img decoding=\"async\" class=\"tex\" src=\"http:\/\/www.electrical-installation.org\/enw\/images\/math\/0\/1\/7\/017c1fb176b565e40b6a973943f37e4a.png\" alt=\"Z1\\, I1=\\left ( Zsign\\, + Z2 \\right )I2\\Rightarrow \\frac{I2}{I1}=\\frac{Z1}{\\left ( Zsign\\, + Z2 \\right )}\" \/><br \/>\nCurrent I2, present on the signal line, disturbs device 2.<\/p>\n<p class=\"figure-title\"><i><b>Fig. R28<\/b><\/i>:\u00a0<i>Definition of common-mode impedance coupling<\/i><\/p>\n<\/div>\n<\/div>\n<\/div>\n<h2><span id=\"Examples\" class=\"mw-headline\"> Examples <\/span><\/h2>\n<p>(see <b>Fig.<\/b> <span class=\"FigRef\">R29<\/span>)<\/p>\n<ul>\n<li>Devices linked by a common reference conductor (e.g. PEN, PE) affected by fast or intense (di\/dt) current variations (fault current, lightning strike, short-circuit, load changes, chopping circuits, harmonic currents, power factor correction capacitor banks, etc.)<\/li>\n<li>A common return path for a number of electrical sources<\/li>\n<\/ul>\n<div class=\"thumb tnone\">\n<div class=\"thumbinner\">\n<p><a class=\"image\" href=\"http:\/\/www.electrical-installation.org\/enw\/index.php?title=File:DB422797_EN.svg&amp;page=1\"><img loading=\"lazy\" decoding=\"async\" class=\"thumbimage\" src=\"http:\/\/www.electrical-installation.org\/enw\/images\/thumb\/e\/e5\/DB422797_EN.svg\/515px-DB422797_EN.svg.png\" alt=\"\" width=\"515\" height=\"280\" \/><\/a><\/p>\n<div class=\"thumbcaption\">\n<p class=\"figure-title\"><i><b>Fig. R29<\/b><\/i>:\u00a0<i>Example of common-mode impedance coupling<\/i><\/p>\n<\/div>\n<\/div>\n<\/div>\n<h2><span id=\"Counter-measures\" class=\"mw-headline\"> Counter-measures <\/span><\/h2>\n<p>(see <b>Fig.<\/b> <span class=\"FigRef\">R30<\/span>)<\/p>\n<p>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:<\/p>\n<ul>\n<li>Reduce impedances:\n<ul>\n<li>Mesh the common references,<\/li>\n<li>Use short cables or flat braids which, for equal sizes, have a lower impedance than round cables,<\/li>\n<li>Install functional equipotential bonding between devices.<\/li>\n<\/ul>\n<\/li>\n<li>Reduce the level of the disturbing currents by adding common-mode filtering and differential-mode inductors<\/li>\n<\/ul>\n<div class=\"thumb tnone\">\n<div class=\"thumbinner\">\n<p><a class=\"image\" href=\"http:\/\/www.electrical-installation.org\/enw\/index.php?title=File:DB422798_EN.svg&amp;page=1\"><img loading=\"lazy\" decoding=\"async\" class=\"thumbimage\" src=\"http:\/\/www.electrical-installation.org\/enw\/images\/thumb\/c\/c5\/DB422798_EN.svg\/453px-DB422798_EN.svg.png\" alt=\"\" width=\"453\" height=\"290\" \/><\/a><\/p>\n<div class=\"thumbcaption\">\n<p class=\"figure-notes\">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.<br \/>\nThe difference in potential between devices 1 and 2 becomes very low and the disturbance acceptable.<\/p>\n<p class=\"figure-title\"><i><b>Fig. R30<\/b><\/i>:\u00a0<i>Counter-measures of common-mode impedance coupling<\/i><\/p>\n<\/div>\n<h1 id=\"firstHeading\" class=\"firstHeading h1Befor\"><span dir=\"auto\">Capacitive coupling<\/span><\/h1>\n<p>Definition<\/p>\n<p>The level of disturbance depends on the voltage variations (dv\/dt) and the value of the coupling capacitance between the disturber and the victim.<br \/>\nCapacitive coupling increases with:<\/p>\n<ul>\n<li>The frequency<\/li>\n<li>The proximity of the disturber to the victim and the length of the parallel cables<\/li>\n<li>The height of the cables with respect to a ground referencing plane<\/li>\n<li>The input impedance of the victim circuit (circuits with a high input impedance are more vulnerable)<\/li>\n<li>The insulation of the victim cable (\u03b5r of the cable insulation), particularly for tightly coupled pairs<\/li>\n<\/ul>\n<p><b>Figure<\/b> <span class=\"FigRef\">R31<\/span> shows the results of capacitive coupling (cross-talk) between two cables.<\/p>\n<div class=\"thumb tnone\">\n<div class=\"thumbinner\">\n<p><a class=\"image\" href=\"http:\/\/www.electrical-installation.org\/enw\/index.php?title=File:DB422799_EN.svg&amp;page=1\"><img loading=\"lazy\" decoding=\"async\" class=\"thumbimage\" src=\"http:\/\/www.electrical-installation.org\/enw\/images\/thumb\/1\/10\/DB422799_EN.svg\/364px-DB422799_EN.svg.png\" alt=\"\" width=\"364\" height=\"361\" \/><\/a><\/p>\n<div class=\"thumbcaption\">\n<p class=\"figure-title\"><i><b>Fig. R31<\/b><\/i>:\u00a0<i>Typical result of capacitive coupling (capacitive cross-talk)<\/i><\/p>\n<\/div>\n<\/div>\n<\/div>\n<h2><span id=\"Examples\" class=\"mw-headline\"> Examples <\/span><\/h2>\n<p>(see <b>Fig.<\/b> <span class=\"FigRef\">R32<\/span>)<\/p>\n<ul>\n<li>Nearby cables subjected to rapid voltage variations (dv\/dt)<\/li>\n<li>Start-up of fluorescent lamps<\/li>\n<li>High-voltage switch-mode power supplies (photocopy machines, etc.)<\/li>\n<li>Coupling capacitance between the primary and secondary windings of transformers<\/li>\n<li>Cross-talk between cables<\/li>\n<\/ul>\n<div class=\"thumb tnone\">\n<div class=\"thumbinner\">\n<p><a class=\"image\" href=\"http:\/\/www.electrical-installation.org\/enw\/index.php?title=File:DB422800_EN.svg&amp;page=1\"><img loading=\"lazy\" decoding=\"async\" class=\"thumbimage\" src=\"http:\/\/www.electrical-installation.org\/enw\/images\/thumb\/c\/ce\/DB422800_EN.svg\/532px-DB422800_EN.svg.png\" alt=\"\" width=\"532\" height=\"392\" \/><\/a><\/p>\n<div class=\"thumbcaption\">\n<p class=\"figure-title\"><i><b>Fig. R32<\/b><\/i>:\u00a0<i>Example of capacitive coupling<\/i><\/p>\n<\/div>\n<\/div>\n<\/div>\n<h2><span id=\"Counter-measures\" class=\"mw-headline\"> Counter-measures <\/span><\/h2>\n<p>(see <b>Fig.<\/b> <span class=\"FigRef\">R33<\/span>)<\/p>\n<ul>\n<li>Limit the length of parallel runs of disturbers and victims to the strict minimum<\/li>\n<li>Increase the distance between the disturber and the victim<\/li>\n<li>For two-wire connections, run the two wires as close together as possible<\/li>\n<li>Position a PEC bonded at both ends and between the disturber and the victim<\/li>\n<li>Use two or four-wire cables rather than individual conductors<\/li>\n<li>Use symmetrical transmission systems on correctly implemented, symmetrical wiring systems<\/li>\n<li>Shield the disturbing cables, the victim cables or both (the shielding must be bonded)<\/li>\n<li>Reduce the dv\/dt of the disturber by increasing the signal rise time where possible<\/li>\n<\/ul>\n<div class=\"thumb tnone\">\n<div class=\"thumbinner\">\n<p><a class=\"image\" href=\"http:\/\/www.electrical-installation.org\/enw\/index.php?title=File:DB422801_EN.svg&amp;page=1\"><img loading=\"lazy\" decoding=\"async\" class=\"thumbimage\" src=\"http:\/\/www.electrical-installation.org\/enw\/images\/thumb\/5\/53\/DB422801_EN.svg\/234px-DB422801_EN.svg.png\" alt=\"\" width=\"234\" height=\"230\" \/><\/a><\/p>\n<div class=\"thumbcaption\">\n<p class=\"figure-title\"><i><b>Fig. R33<\/b><\/i>:\u00a0<i>Cable shielding with perforations reduces capacitive coupling<\/i><\/p>\n<\/div>\n<h1 id=\"firstHeading\" class=\"firstHeading h1Befor\"><span dir=\"auto\">Inductive coupling<\/span><\/h1>\n<p>Definition<\/p>\n<p>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.<\/p>\n<p>Inductive coupling increases with:<\/p>\n<ul>\n<li>The frequency<\/li>\n<li>The proximity of the disturber to the victim and the length of the parallel cables,<\/li>\n<li>The height of the cables with respect to a ground referencing plane,<\/li>\n<li>The load impedance of the disturbing circuit.<\/li>\n<\/ul>\n<h2><span id=\"Examples\" class=\"mw-headline\"> Examples <\/span><\/h2>\n<p>(see <b>Fig.<\/b> <span class=\"FigRef\">R34<\/span>)<\/p>\n<ul>\n<li>Nearby cables subjected to rapid current variations (di\/dt)<\/li>\n<li>Short-circuits<\/li>\n<li>Fault currents<\/li>\n<li>Lightning strikes<\/li>\n<li>Stator control systems<\/li>\n<li>Welding machines<\/li>\n<li>Inductors<\/li>\n<\/ul>\n<div class=\"thumb tnone\">\n<div class=\"thumbinner\">\n<p><a class=\"image\" href=\"http:\/\/www.electrical-installation.org\/enw\/index.php?title=File:DB422802_EN.svg&amp;page=1\"><img loading=\"lazy\" decoding=\"async\" class=\"thumbimage\" src=\"http:\/\/www.electrical-installation.org\/enw\/images\/thumb\/0\/02\/DB422802_EN.svg\/461px-DB422802_EN.svg.png\" alt=\"\" width=\"461\" height=\"249\" \/><\/a><\/p>\n<div class=\"thumbcaption\">\n<p class=\"figure-title\"><i><b>Fig. R34<\/b><\/i>:\u00a0<i>Example of inductive coupling<\/i><\/p>\n<\/div>\n<\/div>\n<\/div>\n<h2><span id=\"Counter-measures\" class=\"mw-headline\"> Counter-measures <\/span><\/h2>\n<ul>\n<li>Limit the length of parallel runs of disturbers and victims to the strict minimum<\/li>\n<li>Increase the distance between the disturber and the victim<\/li>\n<li>For two-wire connections, run the two wires as close together as possible<\/li>\n<li>Use multi-core or touching single-core cables, preferably in a triangular layout<\/li>\n<li>Position a PEC bonded at both ends and between the disturber and the victim<\/li>\n<li>Use symmetrical transmission systems on correctly implemented, symmetrical wiring systems<\/li>\n<li>Shield the disturbing cables, the victim cables or both (the shielding must be bonded)<\/li>\n<li>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)<\/li>\n<\/ul>\n<h1 id=\"firstHeading\" class=\"firstHeading h1Befor\"><span dir=\"auto\">Radiated coupling<\/span><\/h1>\n<p>Definition<\/p>\n<p>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.<\/p>\n<p>The electrical field (E field) and the magnetic field (H field) are coupled in wiring systems via the wires and loops (see <b>Fig.<\/b> <span class=\"FigRef\">R35<\/span>).<\/p>\n<div class=\"thumb tnone\">\n<div class=\"thumbinner\">\n<p><a class=\"image\" href=\"http:\/\/www.electrical-installation.org\/enw\/index.php?title=File:DB422803_EN.svg&amp;page=1\"><img loading=\"lazy\" decoding=\"async\" class=\"thumbimage\" src=\"http:\/\/www.electrical-installation.org\/enw\/images\/thumb\/2\/2a\/DB422803_EN.svg\/362px-DB422803_EN.svg.png\" alt=\"\" width=\"362\" height=\"185\" \/><\/a><\/p>\n<div class=\"thumbcaption\">\n<p class=\"figure-title\"><i><b>Fig. R35<\/b><\/i>:\u00a0<i>Definition of radiated coupling<\/i><\/p>\n<\/div>\n<\/div>\n<\/div>\n<p>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.<\/p>\n<p>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.<\/p>\n<h2><span id=\"Examples\" class=\"mw-headline\"> Examples <\/span><\/h2>\n<p>(see <b>Fig.<\/b> <span class=\"FigRef\">R36<\/span>)<\/p>\n<ul>\n<li>Radio-transmission equipment (walkie-talkies, radio and TV transmitters, mobile services)<\/li>\n<li>Radar<\/li>\n<li>Automobile ignition systems<\/li>\n<li>Arc-welding machines<\/li>\n<li>Induction furnaces<\/li>\n<li>Power switching systems<\/li>\n<li>Electrostatic discharges (ESD)<\/li>\n<li>Lighting<\/li>\n<\/ul>\n<div class=\"thumb tnone\">\n<div class=\"thumbinner\">\n<p><a class=\"image\" href=\"http:\/\/www.electrical-installation.org\/enw\/index.php?title=File:DB422804_EN.svg&amp;page=1\"><img loading=\"lazy\" decoding=\"async\" class=\"thumbimage\" src=\"http:\/\/www.electrical-installation.org\/enw\/images\/thumb\/e\/e0\/DB422804_EN.svg\/544px-DB422804_EN.svg.png\" alt=\"\" width=\"544\" height=\"321\" \/><\/a><\/p>\n<div class=\"thumbcaption\">\n<p class=\"figure-title\"><i><b>Fig. R36<\/b><\/i>:\u00a0<i>Examples of radiated coupling<\/i><\/p>\n<\/div>\n<\/div>\n<\/div>\n<h2><span id=\"Counter-measures\" class=\"mw-headline\"> Counter-measures <\/span><\/h2>\n<p>To minimise the effects of radiated coupling, the measures below are required.<\/p>\n<h3><span id=\"For_field-to-cable_coupling\" class=\"mw-headline\"> For field-to-cable coupling <\/span><\/h3>\n<ul>\n<li>Reduce the antenna effect of the victim by reducing the height (h) of the cable with respect to the ground referencing plane<\/li>\n<li>Place the cable in an uninterrupted, bonded metal cableway (tube, trunking, cable tray)<\/li>\n<li>Use shielded cables that are correctly installed and bonded<\/li>\n<li>Add PECs<\/li>\n<li>Place filters or ferrite rings on the victim cable<\/li>\n<\/ul>\n<h3><span id=\"For_field-to-loop_coupling\" class=\"mw-headline\"> For field-to-loop coupling <\/span><\/h3>\n<ul>\n<li>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.<\/li>\n<\/ul>\n<p>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.<\/p>\n<p>Radiated coupling decreases with the distance and when symmetrical transmission links are used.<\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>from Shenider Signal classes (see Fig. R37) Fig. R37:\u00a0Internal signals can be grouped in four classes Four classes of internal [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center 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