Eaton MTL7700 Instruction Manual

Contents

7INM 7700 R ev 125 WIRING CONNECTIONS5 1 GeneralThis section describes wiring connections as follows:a) Barrier connections Section 5.2b) Connections to plant earth Section 5.3c) Connections to dummy barriers Section 5.45 2 Barrier connectionsEach barrier has 4 or 8 terminals, 2 or 4 on each side, allocated asfollows:Safe areaTerminals 1,2,5 and 6 Safe-area powerand signal linesSections 5.2.1and 5.2.2Hazardous areaTerminals 3,4,7 and 8 Hazardous-areasignal linesSection 5.2.1Torque the screw terminals to 0.4Nm.5 2 1 Signal line connectionsConnect signal lines to the screw terminals at both sides of thebarrier (1 and 2 and/or 5 and 6 at the safe-area side, 3 and 4 and/or7 and 8 at the hazardous-area side). The safe-area terminal 1 is alsoused as a power connection when power is provided from the safearea (see section 5.2.2 for details).Clearly segregate hazardous-area and safe-area cabling as definedby relevant codes of practice, and route cabling to the barriersthrough clearly separated and identified conduits or trunking. Dealwith spare cable cores or screens as described in section 5.2.3.Before making any signal connections from the hazardous area,make sure any energy-storing devices (ie, devices NOT classifiedas ‘simple apparatus’) are certified as being compatible with thebarriers to which they will be connected. Check also that theconnecting cables conform with the cable types specified by thesafety documentation and that the maximum cable parametersspecified in IS catalogue are not exceeded. In general, cableparameters are unlikely to present problems except in installationswhere cables longer than 500m are called for in IIC applications.Do not connect barriers to safe-area equipment that is suppliedfrom (or contains) a source of potential with respect to earth that isgreater than 250V rms or 250V dc under normal or fault conditions,unless this is specifically permitted by the safety documentation.This limitation does not apply to safe-area equipment fed by athree-phase 440V neutral earth supply.See Appendix A for examples of wiring connections for specificapplications.5 2 2 Power supply connections general considerationsTake care that if barriers are connected to a safe-area power supply,connections are made correctly. If the internal safety fuse blows,it will destroy MTL7700 barriers. See Appendix A for specificconnections for individual barriers and applications.5 2 3 Bussed Power applications and connectionsWhen a number of barriers use a common power supply, theoptional power link (BPL7700) can be used. Typical applicationsinclude hazardous-area switches, solenoids and 4–20mAtransmitters; and the barriers it can be used with are the MTL7706,MTL7707+, MTL7787+, MTL7787P+ and MTL774x. See figure14 for a typical power link installation applied to hazardous-areaswitches.Up to 40 barriers can be linked using the power links. The link itselfis supplied from a power feed module (MTL7798). The MTL7798power feed module is provided with a trip circuit which protectsthe barriers by switching off their supply if a fault (such as anovervoltage) occurs in the power source. The state of the moduleis indicated by one of two LED indicators:a) Green ON when supply is normal and being passed to thebarriers.b) Red ON when the trip mechanism is activated indicatinga fault.After a fault has been indicated, the module can be reset bydisconnecting the main power supply.Install the power links as follows (figure 13):a) Mount an MTL7798 power feed module on the DIN-rail at oneend of the column of barriers being supplied.b) Connect a safe-area 20–26V dc supply to terminals 5 and 6 ofthe power feed module.c) select the number of links required.d) Lift the tag holders to gain access to the power link connectorsand insert the links (figure 13).e) Close the tag holders.f) To replace the barrier, lift the identifiers either side of theappropriate barrier to check which one is linked, remove thelink, replace the barrier and re-insert the link and close theidentifiers.WARNINGDo not remove bussed power links with power applied ifinstalled in FM Div 2 / ATEX Zone 25 2 4 Spare cores/screens/0V returns: connectionsUnused cores should be connected to 0V. Terminals on the earthfoot simplify this.5 3 Connections to plant earth5 3 1 General considerationsA barrier installation must be earthed properly for correct and safeoperation. Care must be taken that individual barriers are correctlymounted so that the earth connection with the DIN-rail is secure.An installation must, in turn, be connected to a suitable planthigh-integrity earth. This should be done by connecting suitableconductors to ETL7000 earth terminals (see section 5.3.2). It isalso usually advisable to make sure that the DIN-rail is isolated fromany possible enclosure earths by separating it from the mountingsurface with ISP7000 isolating spacers (see section 4.3.2). Figure 13: Power link insallation