Eaton 9372-FB-P Series Instruction Manual

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Eaton 9372-FB-P Series Instruction Manual Manual pdf 13 page image

INM 9370-RD Rev 511Note: After configuring the required grounding option, tighten all screw terminals toa recommended torque of 0.6 Nm.4.2.3 Permitted enclosure combinationsThe maximum number of redundant intrinsically safe spurs that can be supportedon a trunk segment is 12. The permitted enclosure combinations are shown in Figure4.3.Note that a fieldbus trunk terminator (9378-FT) must be fitted (see Section 4.4) to thelast/furthest enclosure on the segment. See also Figure 4.6.4.3 Trunk connectionsEach enclosure is provided with two access holes for trunk glands; one for theincoming trunk and another for onward linking to an additional enclosure, ifnecessary.WARNING!No part of the Trunk Terminal Assembly may be worked while theenclosure is powered, unless the environment is known to be non-hazardous.4.3.1 Trunk Terminal AssemblyInside the enclosure, the trunk cables are terminated in a Trunk Terminal Assembly(TTA). This is a sub-enclosure with a protective lid, secured with a single screw. Thisassembly, together with its warning label, is intended to deter a user from workingon the trunk connections without isolating trunk power. See Figure 4.4.Trunk cables enter via glands, through the enclosure wall shown at the bottom ofthe diagram, and the grounding stud is accessible on the lower left side. The trunkterminal connectors are in the middle of the assembly to receive the trunk wiring.Terminals are provided to allow a variety of wiring arrangements, according to theparticular requirements of the installation:– “Trunk In” cable only– “Trunk In” and “Trunk Out” cables– Active and spare “Trunk In” cables– Active and spare “Trunk In” cables with overall cable shield– Active and spare “Trunk In” cables and “Trunk Out” cableCAUTIONThe ‘+’ and ‘–’ wires of a ‘spare’ trunk in cable must be connected only to terminalsmarked ‘NC’. This ensures that the spare cable is not electrically connected in parallelwith the ‘active’ trunk in or trunk out cables. The cable shield of the spare cableshould be connected to an ‘S’ terminal.All ‘spare’ trunk-in connections (‘+’, ‘–’ and shield) must be firmly grounded at thehost.4.3.2 Trunk cable wiringCable ferrules should be fitted to all multi-stranded cables being terminated in theTTA.Connect the trunk cable(s) in the following way.a) Loosen the captive screw of the transparent protective cover on the TTA. Slideout the cover and move it to one side to obtain access.b) Prepare the trunk cable(s) in accordance with the gland manufacturer’sinstructions and feed the cable(s) through the gland(s).c) Connect the prepared ends of the fieldbus trunk cable(s) into the appropriate ‘+’, ‘–‘ and ‘S’ terminals, shown in Figure 4.5, and tighten the screw terminals to arecommended torque of 0.6 Nm.