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The bigger the current or voltage, the longer thedistance is required.Ø For communication lines and AI/O signal lines, it is suggested thatthey should be carried within Zinc-gilded tube for crush resistance.Meanwhile, one end of the zinc-gilded tube should be connected tofactory facilities and grounded together.Ø While planning your wire layouts, you should consider layoutsthat can save wire length.E-6ADAM-5000Appendix FFGrounding ReferenceADAM-5000F-1Grounding ReferenceField Grounding and Shielding ApplicationOverviewUnfortunately, it’s impossible to finish the system integration task at atime. We always meet some troubles in field.
Such as communicationnetwork or system isn’t stable, noise influence, and equipment isdamaged or hungs up by thunders. However, the most possible issueis just the improper wiring; ie, grounding and shieldinF. As you knowthe 80/20 rule in our life: we spend 20% time for 80% works, but 80%time for left 20% works. So to system integration, we paid 20% cost forWire / Cable and 80% cost for Equipment.
However, 80% reliabilitydepends on Grounding and ShieldinF. In a word, we just need to pay20% investment and work on those two issues to get a high reliablesystem.This application note will bring you some concepts about fieldgrounding and shieldinF. Below topics will be illustrated in followingpages.1.
Grounding1.1The ‘Earth’ for reference1.2The ‘Frame Ground’ and ‘Grounding Bar’1.3Normal Mode and Common Mode1.4Wire impedance1.5Single Point Grounding2. ShieldingF-22.1Cable Shield2.2System ShieldingADAM-5000Appendix F3. Noise Reduction Techniques4. Check Point ListF.1Grounding1.1 The Earth for referenceWhy we think theEARTH as GROUND?As you know that the EARTH can t be conductive indeed.But those parallel resistors make the EARTH as a singlepoint and just for reference.Figure F-1: Think the EARTH as GROUND.• Why we think the EARTH as GROUND?As you know that the EARTH can not be conductive indeed. But allbuildings base on EARTH.
Steels, concretion and relational cablessuch as Lighting Arrester and power system were connected toEARTH. Think them as resistors, then those infinite parallel resistorsmake the EARTH as a single point and just for reference.ADAM-5000F-3Grounding Reference1.2 The Frame Ground and Grounding BarNNNGSingle Phase, Three LineL110VN220V110VLGGGNeutral is the physical cable from Generator.Ground is the local physical cable that connected toGround Bar .Figure F-2: Grounding Bar.According to previous description, the grounding is the most important issue for our system.
Just like ‘Frame Ground’ of the computer,this signal offers a reference point of the electronic circuit inside thecomputer. When we want to communicate with this computer, not only‘signal ground’, but also ‘frame ground’ should be connected to makea reference point of each other’s electronic circuit. Generally speaking,it’s necessary to build a individual grounding bar for each system,such as computer networks, telecommunication networks, powersystem, .
. . , etc. Those individual grounding bars not only provide theindividual reference point, but also make the earth as a real ground!F-4ADAM-5000Appendix F1.3 Normal Mode and Common ModeFigure F-3: Normal mode and Common mode.Have you ever tried to measure the voltage between ‘Hot’ andconcrete floor, or measure the voltage between ‘Neutral’ and concretefloor? You will get nonsense value with above testinF. ‘Hot’ and‘Neutral’ were just a relational signal, so you will get the AC110V orAC220V by measure those two signal.
Normal mode and commonmode just show you that the ‘frame ground’ is the most importantreference signal for all the systems and equipments.ADAM-5000F-5Grounding ReferenceFigure F-4: Normal mode and Common mode.• Ground-pin is longer than others, for first contact to power systemand noise bypass.• Neutral-pin is broader than Live-pin, for reduce contact impedance.F-6ADAM-5000Appendix F1.4 Wire impedanceT/BAIADAM 5000/485AODCP/SEGrounding BusEConnect to ground bar on the factory.The ground bar should have a resistance below 5 ohm.TrCopper mesh for Shielding(should be grounded only on one end)Grounding BusFigure F-5: The purpose of high voltage transmission• What’s the purpose of high voltage transmission?We can see the high voltage tower stand at suburban.
The power plantraises the voltage while generating the power, then downs the voltagewhen transmits the power to power station. What’s the purpose ofhigh voltage transmission do you think? According to the energyformula, P = V * I, so the current will be reduced while raising thevoltage. Besides, as you know that each cable has the wire impedance.So, referring to Ohm rule (V = I * R), this decreased current makes thelow power consumption. So the high voltage transmission just forreducing the power consumption.Figure F-6: wire impedance.ADAM-5000F-7Grounding ReferenceAbove diagram just shows you that the wire impedance will consumethe power.1.5 Single Point GroundingSingle Point GroundingADAM4013+16 VADAM4014+18 VADAM4017+20 VADAM4021+22 V+24VPowerSupplyThose devices will influence each otherwith swiftly load change.Figure F-7: Single point groundinF.
(1)• What’s Single Point Grounding?Maybe you had some displease experiences just like take hot watershower in Winter. When someone turns on another hot water hydrantnear the Heater, you’ll be impressed with the cold water!The bottom diagram of above figure just shows that those devices willinfluence each other with swiftly load change. For example, normallywe turn on all the four hydrants for testinF.
When you close thehydrant 3 and hydrant 4, the other two hydrants will get a more flow. Inother words, the hydrant can not keep a constant flow rate.F-8ADAM-5000Appendix FSingle Point GroundingADAM4013ADAM4014ADAM4017ADAM4021+16V+18V+20V+228+22V+22V+22V+228ADAM4013ADAM4014ADAM4017+24VPowerSupplyADAM4021+24VPowerSupplyMore cable, but more stable system.Figure F-8: Single point groundinF. (2)Above diagram shows you that single point grounding system will bea more stable system.
Actually, when you use the thin cable poweringthose devices, the end device will get lower power. The thin cable willconsume the energy.F.2Shielding2.1 Cable ShieldFigure F-9: Single isolated cableADAM-5000F-9Grounding Reference• Single isolated cableAbove diagram shows you the structure of the isolated cable. You cansee the isolated layer spiraling Aluminum foil to cover those wires.This spiraled structure makes an isolated layer for isolating the cablesfrom the external noise.Figure F-10: Double isolated cable• Double isolated cableYou can see the double isolated cable structure as figure 10.
The firstisolated layer spiraling Aluminum foil covers those wires. The secondisolated layer spiraling and crossing several nude conductors coverthe first layer shielding and those wires. This spiraled structure makesan isolated layer for isolating those external noise.F-10ADAM-5000Appendix FBesides, following tips just for your reference.• The shield of cable can’t be used for signal ground.The shield is just designed for adhering noise, so the environmentnoise will couple and interfere your system when you use the shield assignal ground.• The density of shield is the higher the better, especially for communication network.• Use double isolated cable for communication network / AI / AO.• Both sides of shields should be connected to their frame while insidethe device.
(for EMI consideration)• Don’t strip off too long of plastic cover for solderinF.2.2 System ShieldingRS-232ADAMADAMADAMADAM4520401340174021Terminal Block+24V* Never stripping too long of the plastic cable cover.* Cascade those shields together by Soldering.PowerSupplyConnect the shield to Frame-Ground of DC Power Supply.Figure F-11: System ShieldingADAM-5000F-11Grounding Reference• Never stripping too long of the plastic cable cover. Otherwise, thisimproper status will destroy the characteristic of the ShieldedTwisted-Pair cable. Besides, those nude wires are easy to adhere thenoise.• Cascade those shields together by “Soldering”. Please refer tofollowing page for further detail explanation.• Connect the shield to Frame-Ground of DC power supply to forcethose adhered noise flow to the ‘frame ground’ of the DC powersupply. (The ‘frame ground’ of the DC power supply should beconnected to the system ground)Figure F-12: The characteristic of the cable• The characteristic of the cableDon’t strip off too long of plastic cover for solderinF.
Otherwise willinfluence the characteristic of the Shielded-Twisted-Pair cable, and willmake an easy way to adhere noise.F-12ADAM-5000Appendix FFigure F-13: System Shielding (1)• Shield connection (1)When you want to visit somewhere, you must like to find out aneasiest way to achieve your goal, aren’t you? So as electronic circuit,all signals use the easiest way. If we connected those two cables justwith few wires, it is a difficult way for signal.
So the noise will try tofind out another path for easier way for flow.Figure F-14:System Shielding (2)ADAM-5000F-13Grounding Reference• Shield connection (2)Above diagram shows you that the fill soldering just makes a easierway for the signal.F.3Noise Reduction Techniques• Enclose noise sources in shield enclosures.• Place sensitive equipment in shielded enclosure and away fromcomputer equipment.• Use separate grounds between noise sources and signals.• Keep ground/signal leads as short as possible.• Use Twisted and Shielded signal leads.• Ground shields on one end ONLY while the reference grounds arenot the same.• It’s almost communication problem while system unstable.• Add another Grounding Bar if necessary.• The diameter of power apply cable must be over 2.0 mm2.• Independent grounding is needed for A/I, A/O, and communicationnetwork while using the jumper box.• Use noise reduction filters if necessary.
(TVS, etc)• You can also refer to FIPS 94 Standard. FIPS 94 recommends that thecomputer system should be placed closer to its power source toeliminate load-induced common mode noise.F-14ADAM-5000Appendix FFigure F-15: Noise Reduction TechniquesF.4Check Point List• Follow the single point grounding rule?• Normal mode and common mode voltage?• Separate the DC and AC ground?• Reject the noise factor?• The shield is connected suitable?• The diameter of wire thick enough?• How about the soldering of connection?• The terminal screw tightly?ADAM-5000F-15Grounding ReferenceF-16ADAM-5000.
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