Eaton Crouse-Hinds Series Instruction Manual

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Eaton Crouse-Hinds Series Instruction Manual Manual pdf 9 page image

DRAFT - 20 November 2014INM 9370-SS Rev 754 INITIAL ELECTRICAL INSTALLATIONWARNING!Before starting any electrical installation work, ensure that theincoming trunk connection is isolated from any source of power.CAUTIONThe temperature inside the enclosure could rise to 75°C. Ensure that all cables andcable glands fitted are rated to withstand these temperatures.4.1 OverviewObtain access to the contents of the enclosure by removing the lid which is secured to thebody of the enclosure by captive screws. Loosen these screws to obtain entry.CAUTIONThe lid is connected to the enclosure body with a protective grounding cable.DO NOT leave the lid hanging by this link cable while work is carried out!• The enclosure receives power from the incoming trunk cable and requires no furthersource of power.• The equipment shall only be powered from supplies conforming to IEC 61158.• Type ‘A’ fieldbus cable is recommended for fieldbus trunk connections.• The terminal blocks for the trunk fieldbus cables have either screw terminalconnectors or cage clamp connectors according to the enclosure model specified, butboth are suitable for cables from 0.5mm2/AWG 20 up to 2.5mm2/AWG 14.On completion of installation, check all blanking plugs and cable glands are tightened toensure IP rating of the enclosure is maintained.For details of the enclosure wiring for the two system types see Appendix 1.4.2 GroundingTwo distinct ground concepts should be recognised before wiring of the enclosure begins:a) Local protective earth-ground - mandatoryb) Cable shieldThese two concepts and their implementation are explained below.4.2.1 Protective local groundThis ground connection is required to ensure that any exposed metal work in, or on, theenclosure does not present a hazard to personnel; it also provides a low impedance earthgrounding circuit for any surge protection items used in the enclosure. An external M10earth-grounding stud is provided on the side wall of the enclosure to enable a connectionto be made to the local ground.Use a ring terminal to make a good quality, plant safety earth connection(4mm2 cross-sectional area or better) to this bolt and tighten it to a recommendedtorque of 5Nm.Note: It is important to prevent this connection from loosening and also to protect it fromcorrosion against the stainless steel grounding stud.Where the trunk and spur cables are protected by steel wire armour, this should betreated as part of the “protective” ground. Normal practice is to bond the armour tothe plant structure at both ends of each cable. Where armour-protected cables enter theFieldbus Barrier enclosure, the armour must be connected to the enclosure body usingsuitable cable glands.4.2.2 Cable shield groundThe cable shield is normally electrically isolated from the protective earth ground,although the two may be deliberately interconnected in some grounding arrangements.