Eaton CEAG AT-S+ Series Mounting And Operating Instructions

Also see for CEAG AT-S+ C30: Operating instructions

Contents

599 FailuresMANUAL CEAG AUtoMAtiC tEst systEM At-s+ 40071860177 (C) December 2016 www.ceag.de9 FailuresAs a basic rule:• Stop device with the main switch when failures occurwhich can cause damage to persons, to property and/orto operational safety.• Additionally disconnect device from power supply andprotect against resetting.• After troubleshooting power up the system as describedin chapter 7.7.9.1 Interference immunity by screeningInterference (e. g. radio interferences) can occur espe-cially in today´s highly automated industries. It can lead tomalfunctions and even to the failure of entire plants. Theoverlaying of different types of interference increases theoverall level of radiated failure, hence the need to protectall devices from electromagnetic interference (EMI). Inindustrial process engineering in particular, a high levelof immunity is required for electrical instrumentationand control (I & C) equipment. This is why all electronicdevices are subject to mandatory CE marking.CEAG products comply with the requirements of ECDirectives 2004/108/EG (EMC directive), 2006/95/EG (lowvoltage directive) and are entitled to carry the CE marking.If luminaires with electronic ballast comply with the EMCdirectives, then the interference produced by the highfrequency operation of the electronic ballast is within thelegal limits. Nevertheless, electronic devices may causeinterference in individual cases. As a rule only HF pagingsystems (in the MHz range) should be used. Reliableoperation cannot be guaranteed with the use of inductivepaging systems (25-40kHz).There are a number of ways in which interference can becontrolled.• Circuits should be separated from one another wherepossible and common returns (GND, Ground) kept asshort as possible.• Parallel cable runs should be kept as short as possible oravoided altogether.• The use of twisted cables can reduce inductive interfer-ence by a factor of 20.• The most important and most common method forsuppressing interference is screening.9.1.1 Cable screensCable screens usually consist of non-magnetic materialssuch as copper or aluminium. The most popular screensfor cables and wires are individual braided screensconsisting of two interwoven sets of wires running inopposite directions.The density and thickness of the braid is the qualitycharacteristic of the screen. It is essential for the screento cover as much as possible of the area of the conductorand so minimize the reciprocal of amplification. CoverNOTEScreen quick connectorsSSA 5-10 for communica-tion lines with a crosssection dimension of 5 to10mm.Order no. 400 71 347 1339.1.2 Screen connectionThe type of screen connection depends mainly on theanticipated interference. Grounding the screen at one end(1) is necessary to suppress electrical fields. Interferencecaused by a magnetic alternating field on the other handcan only be suppressed when the screen is connected atboth ends (2).Ground loops with their familiar disadvantages must beavoided when connecting a screen at both ends. Highvoltage can be induced in large loops and this in turncauses failures. The right way to avoid ground loops is tomake a starshaped ground or to take a Y3-condenser.9.1.3 The fail-safe systemCompanies therefore protect their plants from inducedEMI by screening their cables. Now the cable screen onlyhas to be connected inside the control cabinet to makethe connection to ground. This connection should be low-impedance and with a low inductive resistance. Socalledscreen quick connectors (SSA 5-10) should be used for this.The screen quick connector SSA 5-10 gets grounded bypotential connecting lines.It is of course rare for just one cable to be routed into acontrol cabinet. In most cases a number of data transfer,supply and circuit cables have to be laid into the cabinet.However every opening in the cabinet that can be avoidedis an avoidable cause of interference.NOTEThe avoidanceof ground loopscontributes tothe trouble-freeoperation of asystem.Condenser 220nF Y3  4 KVshould be around 95% to achieve a good screen. At 60%and below there is no guarantee of reliable immunity.