Eaton Crouse-Hinds Series Instruction Manual

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Eaton Crouse-Hinds Series Instruction Manual Manual pdf 11 page image

DRAFT - 20 November 2014INM 9370-SS Rev 774.3 Trunk connectionsEach enclosure is provided with two access holes for trunk glands; one for the incomingtrunk and another for onward linking to an additional enclosure, if necessary.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. This assembly,together with its warning label, is intended to deter a user from working on the trunkconnections without isolating trunk power. See Figure 4.4.Trunk cables enter via glands, through the enclosure wall shown at the bottom of thediagram, and the grounding stud is accessible on the lower left side. The trunk terminalconnectors are in the middle of the assembly to receive the trunk wiring.Depending upon model type chosen, the enclosure will accommodate 6 or 12 spurs.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 Permitted enclosure combinationsThe maximum number of intrinsically safe spurs that can be supported per segmentusing 9370-FB range of Fieldbus Barriers is 18.The permitted enclosure combinations are shown in Figure 4.3. See also Figure 4.4 andSection 4.4.Connect the trunk cable(s) in the following way.a) Loosen the captive screw of the transparent protective cover on the TTA. Slide out thecover and move it to one side to obtain access.b) Prepare the trunk cable(s) in accordance with the gland manufacturer’s instructionsand secure the cable(s) in the gland(s). Ensure that the cables are not strained.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.Note: Figure 4.5 shows the screw-terminal ‘-PS’ enclosure option, but the ‘-PC’ cage-clamp terminal arrangement is similar.Check Section 4.2.2 to confirm that the chosen fieldbus-ground option is correctlywired, and adjust if necessary.d) Replace the transparent protective cover over the terminal block and secure it with theretaining screw to a recommended torque of 0.6 Nm.