Eaton MTL7700 Instruction Manual

Contents

1INM 7700 R ev 12MTL7700 rangeShunt-diode safety barriersFigure 1: MTL7700 range of shunt-diode safety barriers1 OVERVIEWThis instruction manual contains all information needed to install,maintain, fault-find and test MTL7700 range of shunt-diode safetybarriers.Section 3 includes a checklist of essential safety factors thatmust be considered when using MTL7700 range of barriers asintrinsically safe (IS) interfaces between safe and hazardous areas.Read section 3 before beginning installation. Users within theEuropean Community should also refer to the website for multiplelanguage safety instructions.It is assumed that all necessary system design, specificationand engineering factors have been taken into account BEFOREinstallation work begins. To assist pre-planning, the followingpublications covering the theory, design, application, specificationsand certification of shunt-diode safety barriers are available:AN9003 Application Note: A user’s guide tointrinsic safetyAN9007 Application Note: A user’s guide toMTL700 range of shunt-diode safetybarriersIS catalogue The IS catalogue includes detailedspecifications of all MTL7700 range ofbarriers and accessoriesIS certificates Copies of Baseefa, FM and CSA ISapparatus and system certificates forMTL7700 range of barriersIf not supplied with the product, these publications are availableeither from our website (www.mtl-inst.com) or on request fromyour local office.2 DESCRIPTION2 1 IntroductionMTL7700 range of ‘fourth-generation’ intrinsically safe shunt-diodesafety barriers are innovative successors to the MTL700 range.MTL7700 range of barriers are 1-, 2- or 3-channel devices thatuse intrinsically safe explosion-protection techniques to passelectrical signals between safe and hazardous areas, whilstlimiting transferred energy to a level that cannot ignite flammableatmospheres.Connected in series with wiring entering any hazardous area onprocess plant, MTL7700 range of barriers prevent explosions in allnormally occurring explosive atmospheres – including mixtures ofair with flammable gases, vapours, dusts and fibres – if a fault orfaults develop in the safe area.2 2 MTL7700 range – barrier rangesThe range is based on a choice of models which, betweenthem, cover virtually all applications – including the protection ofinstallations incorporating uncertified devices known as ‘simpleapparatus’ (eg, switches, thermocouples, resistive sensors,photocells and LEDs) or separately certified ‘energy-storing’ or‘voltage-producing apparatus’ (eg, ac sensors, proximity detectors,transmitters and current-to pneumatic (I/P) converters. Beingintrinsically safe, shunt-diode barriers enable maintenance work orcalibration to be carried out ‘live’ without additional precautions. Tosimplify selection, several ‘key’ barriers (see table 1) are highlightedas meeting the majority of process control requirements.