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    Publication 1770-4.1 – February 1998Industrial Automation Wiring andGrounding GuidelinesThis publication gives you general guidelines for installing anAllen-Bradley industrial automation system that may includeprogrammable controllers, industrial computers, operator-interfaceterminals, display...

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    Industrial Automation Wiring and Grounding Guidelines2Publication 1770-4.1 – February 1998The raceway layout of a system is reflective of where the differenttypes of I/O modules are placed in I/O chassis. Therefore, youshould determine I/O-module placement prior to any layout androuting of w...

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    Industrial Automation Wiring and Grounding Guidelines3Publication 1770-4.1 – February 1998Route ConductorsTo guard against coupling noise from one conductor to another,follow these general guidelines (Table B) when routing wires andcables (both inside and outside of an enclosure). Use the sp...

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    Industrial Automation Wiring and Grounding Guidelines4Publication 1770-4.1 – February 1998Figure 1Mounting Assembly DetailsCategory-2ConductorsEnclosure Wall12618-II/O BlockTransformerUse greater spacing withoutconduitTighter spacingallowed with conduitTighter spacing allowed where force...

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    Industrial Automation Wiring and Grounding Guidelines5Publication 1770-4.1 – February 1998Mounting and Bonding the ChassisYou can mount the chassis with either bolts or welded studs.Figure 2 shows details for:• stud-mounting a ground bus or chassis to the back panel of theenclosure• stud-...

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    Industrial Automation Wiring and Grounding Guidelines6Publication 1770-4.1 – February 1998Make good electrical connection between each chassis, back-panel,and enclosure through each mounting bolt or stud. Wherever contactis made, remove paint or other non-conductive finish from aroundstuds o...

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    Industrial Automation Wiring and Grounding Guidelines7Publication 1770-4.1 – February 1998Figure 4Details of Ground Connection at Enclosure Walland use a star washer.10020EnclosureWallScrapePaintBoltScrape paint on enclosure wallGroundLugNutStarWasherEquipment-GroundingConductorConnect an equ...

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    Industrial Automation Wiring and Grounding Guidelines8Publication 1770-4.1 – February 1998Figure 6Typical Grounding ConfigurationEnclosure WallI/O Chassis WallNutGround Lug14 AWG14 AWG15317See Figure 3See Figure 4FLEX I/O™ ModulesDIN RailStarWasherStarWashersGroundLugGroundBusMini-processor...

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    Industrial Automation Wiring and Grounding Guidelines9Publication 1770-4.1 – February 1998Some products have no visible groundable chassis and no ground lugor ground terminal, but mount on a DIN rail. The FLEX I/Oproducts are in this category. The chassis of these products aregrounded only ...

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    Industrial Automation Wiring and Grounding Guidelines10Publication 1770-4.1 – February 1998You can connect the power supply directly to the secondary of atransformer (Figures 7 and 8). The transformer provides dc isolationfrom other equipment not connected to that transformer secondary.Conne...

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    Industrial Automation Wiring and Grounding Guidelines11Publication 1770-4.1 – February 1998Connect one input directly to the L1 side of the line, on the load sideof the CRM contacts, to detect whether the CRM contacts areclosed. In the ladder logic, use this input to hold off all outputsanyt...

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    Industrial Automation Wiring and Grounding Guidelines12Publication 1770-4.1 – February 1998Common Power Source for I/OUnless each I/O of a module or block is individually isolated,multiple I/O within the block or module share a common terminalfor one side of the power source. All I/O sharing...

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    Industrial Automation Wiring and Grounding Guidelines13Publication 1770-4.1 – February 1998For example, the external-transformer load of a 1771-P4Spower-supply module at maximum backplane load current is 140VA(2.5 x 56W = 140). A 140VA transformer could be used if a1771-P4S power-supply modu...

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    Industrial Automation Wiring and Grounding Guidelines14Publication 1770-4.1 – February 1998Isolation Transformer — For applications near excessiveelectrical noise generators, an isolation transformer (for the secondtransformer) provides further suppression of electromagneticinterference f...

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    Industrial Automation Wiring and Grounding Guidelines15Publication 1770-4.1 – February 1998Transient emi can be generated whenever inductive loads such asrelays, solenoids, motor starters, or motors are operated by “hardcontacts” such as pushbutton or selector switches. The wiringguideli...

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    Industrial Automation Wiring and Grounding Guidelines16Publication 1770-4.1 – February 1998Figure 10Examples of where to use Suppression12597-Iac output modulesolid-stateL1L21MSL1switch1MS1MsuppressorL2Although the motor starter is aninductive load, it does not need asuppressor because it is ...

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    Industrial Automation Wiring and Grounding Guidelines17Publication 1770-4.1 – February 1998Figure 11Typical Suppression Applications+–230/460V ac120V acCat. No. 700-N243-PhaseMotor120/240V acV dc700-Nx12057Electrocube 1676-13For 3-phase apparatus, a suppressor is needed across each phaseFor...

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    Industrial Automation Wiring and Grounding Guidelines18Publication 1770-4.1 – February 1998Surge-suppressors are usually most effective when connected at theinductive loads. They are still usable when connected at theswitching devices; however, this may be less effective because thewires co...

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    Industrial Automation Wiring and Grounding Guidelines19Publication 1770-4.1 – February 1998Unintentional turn-on of outputs as the power source is connected ordisconnected, even if momentary, can result in injury to personnel aswell as damage to equipment. The danger is greater withfast-resp...

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