earthing

IKRAMIKRAM 11EARTHINGEARTHING

SISTEM SISTEM PEMBUMIANPEMBUMIAN

by:by:

MUSTAFFA KAMAL BIN AB. MUSTAFFA KAMAL BIN AB. SAMADSAMAD

JKR ELEKTRIK. SELANGOR D.EJKR ELEKTRIK. SELANGOR D.E

IKRAMIKRAM EARTHINGEARTHING 22

TUJUAN PEMBUMIANTUJUAN PEMBUMIAN• Mengalirkan arus bocor kebumi dengan seberapa

banyak dan cepat supaya alat perlindungan, geganti atau peranti perlindungan dapat berfungsi dengan berkesan bagi mengelakkan berlakunya kejutan elektrik

• Mendapatkan voltan rujukan kosong untuk star point alatubah dan janakuasa supaya talian neutral dapat digunakan dan voltan bekalan stabil serta mengelakkan voltan terapong

• Mendapatkan voltan samaupaya (equipotential voltage) supaya tidak berlaku step voltage bahan pengalir yang terdedah (exposed conductive parts)


CLASIFICATION OF EARTHING CLASIFICATION OF EARTHING SYSTEMSYSTEM

• Supply authority or supply source earthing arrangement are indicated by the first letter:

• T – one or more points of supply are directly connected to earth

• I – supply system not earth, or one point earth through a fault limiting impedance



• Relationship of exposed conductive parts to earth are indicated by the second letter

• T – exposed conductive parts connected directly to earth and which is independent of the supply earth

• N – exposed conductive parts connected directly to the earth point of the source of the supply



• Arrangement of neutral and protective conductors in T-N system is indicated by a third letter

• S – separate neutral and protective conductors

• C – neutral and protective conductors combined in a single conductor


EARTHING SYSTEMEARTHING SYSTEM

• For normal installation practice, earthing is to connect together the exposed conductive parts of various items of the equipment to a common terminal (main earthing terminal), this in turn is connected by the earthing conductor to an earth electrode, buried in the mass of earth.

• The earth installation must be capable of carrying the prospective fault currents without danger and without excessive heat. It must have low resistance at all times with good resistance to corrosion.


ELECTRODEELECTRODE

• The most important part of the earthing system is the electrode.

• Electrode are made from a number of materials like cast iron, steel, copper or stainless steel and they may be in the form of plate, tubes, rods or strips.

• The most favored material is copper which has good conductivity, is corrosion resistance to many of the salts that exist in the soil and it is a material that is easily worked.


ELECTRODEELECTRODE

• These consist of some form of deeply buried conductor, since the major earth resistance lies on the top soil

• Buried copper or galvanized earth plate have largely given place to threaded copper-clad steel-cored rods


TYPES OF ELECTRODETYPES OF ELECTRODE

• Earth rods or pipes• Earth tapes or wires• Earth plates• Earth electrodes embedded in foundation• Metallic reinforcement of concrete structure• Metal pipes• Lead sheaths or other metallic covering of

cables


EARTH RESISTANCEEARTH RESISTANCE

• The earth resistance depends on soil resistivity and characteristic. The type of soil suitable for earth electrode are:

• Wet marshy ground

• Clay, loam soil, arable land

• Clay soil, loam mixed with small quantity of sand

• Damp and wet sand



• Achieving a good earth will depend on local soil condition. Three factors that affect the soil resistivity are:

• Moisture content of the soil

• Chemical composition of the soil

• Temperature of the soil



• In area of high soil resistivity, it is difficult to obtain an earth resistance say one ohm or less. Several option are available in the form of soil conditioning agent e.g copper sulphate, sodium carbonate, bentonite and marconite


APA YANG PERLU APA YANG PERLU DIBUMIKANDIBUMIKAN

• Semua peralatan elektrik yang dibuat dari logam atau bahan yang boleh mengalirkan elektrik, samada alatan elektrik ataupun bukan

• Star point alatubah dan janakuasa

• Terminal bumi DB, lampu, soket 13A, dsb.

• Konduit, trunking, tray, riser, busduct, dan apa-apa jua bahagian logam pemasangan elektrik


EARTH PLATE


STEP VOLTAGE


AVERAGE RESISTIVITY OF AVERAGE RESISTIVITY OF THE EARTHTHE EARTH

Type of Earth Resistivity/Ohm-meters

Wet organic soil 10

Moist soil 100

Dry soil 1000

Bed rock 10000


JENIS KABEL BUMIJENIS KABEL BUMI

• PVC hijau

• PVC hitam untuk star point janakuasa

• Pita tembaga (copper tape) – 3mm x 25mm

• Pita Aluminium

• G.I cable


SAIZ KABEL BUMISAIZ KABEL BUMI

• Sama dengan saiz kabel fasa sehingga 16mm²• 16mm² jika saiz kabel fasa diantara 16mm²

hingga 35mm²• Separuh dari saiz kabel fasa jika saiz kabel fasa

melebehi 35mm²• Gunakan pita tembaga 3mm x 25mm jika saiz

kabel bumi melebehi 70mm²• CENTRAL earthing bar 50mm x 6mm


CENTRAL EARTHING BAR


EARTH CHAMBER


JENIS-JENIS ELEKTROD JENIS-JENIS ELEKTROD BUMIBUMI

• Standard copper-jacketed steel core earth rod 16mm diameter and 1500mm long

• G.I pipe 2 in diameter

• Wire mesh

• Building steel reinforcement

• Javelin rod (overhead line)


UJIAN ELEKTRODBUMI


RINTANGAN ELEKTROD RINTANGAN ELEKTROD BUMIBUMI

Elektrod bumi pemasangan 1 ohm

Elektrod bumi penangkap kilat 10 ohms

Transformer and generating station 10,000 kVA and over

2 ohms

Small transformer stations and distributing stations

10 ohms

Small outdoor station 15 ohms

Distribution transformer installation 25 ohms


JENIS SAMBUNGAN KE JENIS SAMBUNGAN KE ELEKTRODELEKTROD

• Earth clip• Plumbed joint• Brazing (copper)• Bolt & nut / socketing• Riverting• Exothermic welding (CADWELD/FURSE

WELD)• Cold pressure welding


COPPER TAPEPEMBUMIANSEMASAPEMBINAAN


H.T SWITCHBOARDEARTHING


PEMBUMIANSUISGIARMENGGUNAKANCOPPERBRAID


FEEDERPILLAREARTHING


DOWN CONDUCTOR INSPECTION POINT


DOWNCONDUCTORINSPECTIONPOINT


PEMBUMIANPAPAN SUIS


PEMBUMIAN BILIK SUIS


PEMBUMIANDIBAWAHTIANG TALIANAERIAL


PEMBUMIANDIPENAMATANKABEL


PEMBUMIANDIPENAMATANKABELDANSTAR POINTALATUBAH

earthing

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