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Earthing

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How Earthing works. What is earthing all in one for students and others? Types of Earthing. description that is needed. You can get to know how important Earthing is.

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Earthing

  1. 1. EARTHINGEARTHING ByBy Aditya JeeAditya Jee Class -Class -IX BIX B Roll NoRoll No..-- 0202
  2. 2. ContentContent  IntroductionIntroduction  ImportanceImportance  UsesUses  Types of EarthingTypes of Earthing  PhotosPhotos
  3. 3. IntroductionIntroduction In electricity supply systems, an earthing (grounding)In electricity supply systems, an earthing (grounding) system defines the electrical potential of thesystem defines the electrical potential of the conductors relative to that of the Earth's conductiveconductors relative to that of the Earth's conductive surface. The choice of earthing system hassurface. The choice of earthing system has implications for the safety and electromagneticimplications for the safety and electromagnetic compatibility of the power supply. A functional earthcompatibility of the power supply. A functional earth connection serves a purpose other than providingconnection serves a purpose other than providing protection against electrical shock. In contrast to aprotection against electrical shock. In contrast to a protective earth connection, a functional earthprotective earth connection, a functional earth connection may carry a current during the normalconnection may carry a current during the normal operation of a device. Functional earth connectionsoperation of a device. Functional earth connections may be required by devices such as surgemay be required by devices such as surge suppression and electromagnetic-compatibility filters,suppression and electromagnetic-compatibility filters, some types of antennas and various measurementsome types of antennas and various measurement instruments. Generally the protective earth is alsoinstruments. Generally the protective earth is also used as a functional earth, though this requires care inused as a functional earth, though this requires care in some situations.some situations.
  4. 4. ImportanceImportance Earthing is as important as the fuses in the wiringEarthing is as important as the fuses in the wiring circuits i.e. in the case of short circuits or overcircuits i.e. in the case of short circuits or over loads, the heavy current flows through the wiresloads, the heavy current flows through the wires and fitting etc. which melts the fuse wire and stopsand fitting etc. which melts the fuse wire and stops the flow of current in the circuits, thus save thethe flow of current in the circuits, thus save the whole circuit from being damaged.whole circuit from being damaged. Similarly, when any live or phase wire touches theSimilarly, when any live or phase wire touches the metal part of the fitting, appliance, machine ormetal part of the fitting, appliance, machine or equipment, the current passes through the earthequipment, the current passes through the earth wire, if the appliance, equipment or machine etc.wire, if the appliance, equipment or machine etc. are connected with proper earth connection, blowsare connected with proper earth connection, blows the fuse at once and saves the operator fromthe fuse at once and saves the operator from getting shock. Thus to avoid these dangers, allgetting shock. Thus to avoid these dangers, all metal parts of the fitting, appliances, equipment,metal parts of the fitting, appliances, equipment, machines etc are earthed.machines etc are earthed.
  5. 5. UsesUses In mains-In mains-  powered equipment, exposed metalpowered equipment, exposed metal parts are connected to ground to prevent userparts are connected to ground to prevent user contact with dangerous voltage if electricalcontact with dangerous voltage if electrical insulation fails. Connections to ground limit theinsulation fails. Connections to ground limit the build-up of static electricity when handlingbuild-up of static electricity when handling flammable products or electrostatic-sensitiveflammable products or electrostatic-sensitive devices. In some telegraph and powerdevices. In some telegraph and power transmission circuits, the earth itself can betransmission circuits, the earth itself can be used as one conductor of the circuit, savingused as one conductor of the circuit, saving the cost of installing a separate returnthe cost of installing a separate return conductor.conductor.
  6. 6. For measurement purposes-For measurement purposes- the Earth serves as athe Earth serves as a (reasonably) constant potential reference(reasonably) constant potential reference against which other potentials can beagainst which other potentials can be measured.measured. An electrical ground system shouldAn electrical ground system should have anhave an appropriate current-carryingappropriate current-carrying capability to serve ascapability to serve as an adequate zero-an adequate zero- voltage reference level.voltage reference level. In electronic circuitIn electronic circuit theory, a "ground" is usuallytheory, a "ground" is usually idealized as anidealized as an Infinite source or sinks for charge,Infinite source or sinks for charge, which canwhich can absorb an unlimited amount of currentabsorb an unlimited amount of current withoutwithout changing its potential. Where a realchanging its potential. Where a real groundground connection has a significant resistance,connection has a significant resistance, thethe approximation of zero potential is no longerapproximation of zero potential is no longer valid. Stray voltages or earth potentialvalid. Stray voltages or earth potential rise effectsrise effects willwill occur, which may createoccur, which may create noise in signals ornoise in signals or if largeif large enough willenough will produce an electricproduce an electric shock hazard.shock hazard.
  7. 7. Electrical power distribution-Electrical power distribution- These systems are often connected to ground toThese systems are often connected to ground to limit the voltage that can appear on distributionlimit the voltage that can appear on distribution circuits. A distribution system insulated fromcircuits. A distribution system insulated from ground may attain a high potential due toground may attain a high potential due to transient voltages caused by arcing, statictransient voltages caused by arcing, static electricity, or accidental contact with higherelectricity, or accidental contact with higher potential circuits. A ground connection of thepotential circuits. A ground connection of the system dissipates such potentials and limits thesystem dissipates such potentials and limits the rise in voltage of the grounded system.rise in voltage of the grounded system. Types of EarthingTypes of Earthing
  8. 8. Equipment earthing conductors-Equipment earthing conductors-   It provide an electrical connection between nonIt provide an electrical connection between non current-carrying metallic parts of equipmentcurrent-carrying metallic parts of equipment and the earth. According to the U.S. Nationaland the earth. According to the U.S. National Electrical Code (NEC), the reason for doing this isElectrical Code (NEC), the reason for doing this is toto limit the voltage imposed by lightning, line surges,limit the voltage imposed by lightning, line surges, and contact with higher voltageand contact with higher voltage lines. The equipment earthinglines. The equipment earthing conductor is usually also usedconductor is usually also used as the equipment bondingas the equipment bonding conductor.conductor.
  9. 9. Equipment bonding conductors-Equipment bonding conductors-   IItt provide a low impedanceprovide a low impedance path between non-current-carrying metallic parts ofpath between non-current-carrying metallic parts of equipment and one of the conductors of that electricalequipment and one of the conductors of that electrical system's source, so that if a part becomes energized forsystem's source, so that if a part becomes energized for any reason, such as a frayed or damaged conductor, aany reason, such as a frayed or damaged conductor, a short circuit will occur and operate a circuit breaker or fuseshort circuit will occur and operate a circuit breaker or fuse to disconnect the faulted circuit. Note that the earth itselfto disconnect the faulted circuit. Note that the earth itself has no role in this fault-clearing process since current musthas no role in this fault-clearing process since current must return to its source, not the earth as is sometimes believed.return to its source, not the earth as is sometimes believed. By bonding all exposed non-current carrying metal objectsBy bonding all exposed non-current carrying metal objects together, they should remain near the same potential thustogether, they should remain near the same potential thus reducing the chance of a shock. This is especiallyreducing the chance of a shock. This is especially important in bathrooms where one may be in contact withimportant in bathrooms where one may be in contact with several different metallic systems such as supply and drainseveral different metallic systems such as supply and drain pipes and appliance frames. The equipment bondingpipes and appliance frames. The equipment bonding conductor is usually also used as the equipment earthingconductor is usually also used as the equipment earthing conductor.conductor.
  10. 10. PhotosPhotos

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