what is earthing in electricity

The main purpose for earthing in electricity networks is for security. When all metal elements of electric device are grounded, if the insulation in the gadget fails then no risky voltage is present inside the case of the system. If the live cord touches the grounded case the circuit is efficiently shorted and the fuse will right now blow. Hazardous voltages depart while the fuse blows.

Why We Need Earthing:

To Safe Human life/ Building/Equipment's:

To keep human lifestyles from the hazard of electric surprise or death through blowing the fuse.
To provide an alternate route for fault contemporary so that it does not endanger the person to guard buildings, equipment and system in the occasion of chance Lie.
To ensure that all exposed conductive parts do now not attain a dangerous potential.
Providing safe passage to circulate energy and short circuit currents.
To offer a stable platform for operation of touchy electronic devices.
To hold voltage on part of an electrical system at a known cost so as to prevent contemporary or immoderate voltage on equipment or devices.

What is Earthing in electricity

To Protect from Over Voltage:

Power, line surges or inadvertent touch with excessive voltage strains can motive dangerously excessive voltages to the energy distribution device. Earthing provides an alternate direction across the electrical gadget to decrease losses in the device.

To stabilize Voltage:

There are many sources of earthing in electricity. Each transformer may be considered a separate source. If there was now not a commonplace reference factor for some of these voltage sources, it might be extremely hard to calculate their dating to every other. Earth is the most ubiquitous conductive surface, and therefore it was adopted at the beginning of power distribution systems as an almost universal standard for all electrical.

Types of earthing:

Plate Earthing:

Generally for plate type earthing normal Practice is to use
Cast iron plate of size 600 mm x600 mm x12 mm. OR
Galvanized iron plate of size 600 mm x600 mm x6 mm. OR
Copper plate of size 600 mm * 600 mm * 3.15 mm
Plate burred at the depth of 8 feet in the vertical position and GI strip of size 50 mmx6 mm bolted with the plate is brought up to the ground level.
These types of earth pit are generally filled with alternate layer of charcoal & salt up to 4 feet from the bottom of the pit.

Pipe Earthing:

Pipe earthing common practice, use a 10 mm long welded 75 mm diameter GI pipe [C-Class] of 75 mm diameter, which has a GI flange with 6 number holes for earth wiring connections. And is put into the ground by the auger method. Earth pits of this type are usually filled with charcoal and salt or an alternate layer of the earth's reactivation complex.

Construction of Earthing Pit:

Excavation on earth for a normal earth Pit size is 1.5M X 1.5M X 3.0 M.
Use 500 mm X 500 mm X 10 mm GI Plate or Bigger Size for more Contact of Earth and reduce Earth Resistance.
Make a mixture of Wood Coal Powder Salt & Sand all in equal part
Wood Coal Powder use as good conductor of electricity, anti corrosive, rust proves for GI Plate for long life.
The purpose of coal and salt is to keep wet the soil permanently.
The salt percolates and coal absorbs water keeping the soil wet.
Care should always be taken by watering the earth pits in summer so that the pit soil will be wet.
Coal is made of carbon which is good conductor minimizing the earth resistant.
Salt use as electrolyte to form conductivity between GI Plate Coal and Earth with humidity.
Sand has used to form porosity to cycle water & humidity around the mixture.
Put GI Plate (EARTH PLATE) of size 500 mm X 500 mm X 10 mm in the mid of mixture.
Use Double GI Strip size 30 mm X 10 mm to connect GI Plate to System Earthling.
It will be better to use GI Pipe of size 2.5″ diameter with a Flange on the top of GI Pipe to cover GI Strip from EARTH PLATE to Top Flange.
Cover Top of GI pipe with a T joint to avoid jamming of pipe with dust & mud and also use water time to time through this pipe to bottom of earth plate. Maintain less than one Ohm Resistance from EARTH PIT conductor to a distance of 15 Meters around the EARTH PIT with another conductor dip on the Earth at least 500 mm deep.
Check Voltage between Earth Pit conductors to Neutral of Mains Supply 220V AC 50 Hz it should be less than 2.0 Volts.

Affecting on Earth Conductivity:

Resistance of Soil:

It is the resistance of the soil to the passage of electric modern-day. The earth resistance value (ohmic value) of the earth pit depends on the resistivity of the soil. It is the resistance of the soil to the passage of electric modern.

It varies from soil to soil. It depends on the physical structure of the soil, moisture, dissolved salts, grain length and distribution, seasonal change, current quantity. The composition of the soil relies upon at the moisture content, dissolved salt, grain length and its distribution, seasonal variation. Current quantity.

Condition of Soil:

Most soils are very bad conductors of energy when they dry up completely. Soil resistivity is measured in ohms-meters or ohms-cm.

Clay plays an vital position in figuring out the overall performance of electrodes.

Soils with low resistivity are distinctly corrosive. If the soil is dry, the soil resistivity cost may be very high.

If the soil resistivity is high, the earth resistance of the electrode will also be high.

Moisture In Soil:

Moisture has a great effect on the resistivity value of soil. The resistivity of a soil can be determined only by the amount of water held by the soil and the resistivity of the water. The flow of electricity in the soil is through water.

The resistance falls speedy to a more or less solid minimum price of approximately 15% moisture. And further increase in soil moisture level may have little impact on soil resistivity. In many places the water desk is going down in dry weather conditions. Therefore, to keep moisture in dry weather conditions it's miles essential to pour water into and across the Earth's pit.

Salts:

Pure water is a terrible conductor of electricity.

The resistivity of soil relies upon at the resistivity of water which in turn relies upon on the quantity and nature of the salts dissolved in it.

A small amount of salt in water reduces soil resistivity through 80%. Common salt is the best for enhancing soil conductivity. But it weakens the metal and consequently discourages it.

Weather Condition:

Increase or decrease of moisture content determines the increase or decrease of soil resistivity.

Thus in dry whether resistivity will be very high and in monsoon months the resistivity will be low.

Composition of Soil:

Different soil composition gives different average resistivity. Based on the type of soil, the resistivity of clay soil may be in the range of 4 – 150 ohm-meter, whereas for rocky or gravel soils, the same may be well above 1000 ohm-meter.

Earth Pit:

Location also contributes to resistivity to a large extent. In a sloping landscape, or in soil-covered lands, or areas that are hilly, rocky, or sandy, water flows and the water table moves down very rapidly in dry weather conditions. In such a situation the back fill compound will not be able to attract moisture, as the soil around the pit will be dry. Earth pits located in such areas should be watered at frequent intervals, especially during dry weather conditions.

However, the fill compound retains moisture under normal conditions, it moisturizes the dry soil around the electrode during the dry season, and loses moisture over a period of time in the process. Therefore, choose a site that is not naturally well drained.

Grain size:

Grain size, its distribution and proximity to packing are also contributing factors, as they control the way moisture is conducted in the soil.

Effect of seasonal variation on soil resistivity: The increase or decrease in moisture content in soil determines the decrease or increase in soil resistivity. Thus the resistivity will be very high in the dry season and the resistivity will be low in the rainy season.

Current Magnitude:

The resistivity of the soil in the vicinity of the ground electrode may be affected by the flow from the electrode to the surrounding soil. The thermal characteristics and soil moisture will determine whether the current of a given magnitude and duration will cause significant drying and thus increase the soil resistivity effect

Distance between the Electrode:

A single electrode rod or strip or plate alone will not achieve the desired resistance. If multiple electrodes can be installed and desired interconnected resistance can be achieved. The distance between the electrodes must be equal to the depth operated to avoid overlapping of the affected area. Therefore, each electrode must be outside the resistance region of the other.

Obstructions:

The soil may look good on the surface but a few feet down like virgin rock. In that event the resistivity will be affected. Constraints like concrete structure about pits will affect the resistivity. If the Earth's pits are close, the resistance value will be higher.

Earthing More:

Electrode and Earthing Pit:

The earth resistance of pipe or plate electrodes decreases rapidly within a few feet (mostly 2 to 3 m) before the ground but the resistivity of the soil is mostly the same after that. After about 4 m depth, there is no appreciable change in the earth's resistance to the electrode. A long rod should be preferred except for the number of rods in parallel.

Salt and Charcoal:

To reduce soil resistivity, it is necessary to dissolve in the soil moisture particle.

Some substances, such as salt / charcoal, are highly conductive in water solutions, but additive substances reduce the resistivity of the soil, only when it dissolves in moisture in the soil after which the excess volume does not function as intended.

5% moisture in salt rapidly reduces the resistivity of the earth and further increase in salt content will lead to a very small decrease in soil resistivity.

Salt content is expressed in percentage according to the amount of moisture in the soil. Considering 1M3 of soil, 10 percent moisture would be around 144 kg. (10 percent of 1440 kg). The salt content will be 5% of this (ie) 5% of 144kg, ie about 7.2kg.

Water Purring:

Moisture content is one of the controlling factors of earth resistivity.

Above 20% of the moisture content, the resistivity is much less affected. But resistivity below 20% increases rapidly with decrease in moisture content.

If the moisture content is already above 20%, then there is no point in adding water content to the Earth's pit, except perhaps to waste an important and scarce national resource such as water.

Length and Diameter of Electrode:

In addition to mechanical strength considerations, there is little benefit to be gained from increasing the earth electrode diameter with the object to increase the surface area in contact with the soil.

The common practice is to select a diameter of the earth electrode, which will be sufficient power to enable it to operate in special soil conditions without bending or splitting. Larger diameter electrodes may be more difficult to drive than smaller diameter electrodes.

The depth at which an earth electrode is driven has a much greater effect on its electrical resistance characteristics than its diameter.

Maximum Earth resistance for different event:

Major power station= 0.5 Ohm. Major Sub-stations= 1.0 Ohm Minor Sub-station = 2 Ohm Neutral Bushing. =2 Ohm Service connection = 4 Ohm Medium Voltage Network =2 Ohm L.T.Lightening Arrestor= 4 Ohm L.T.Pole= 5 Ohm H.T.Pole =10 Ohm Tower =20-30 Ohm

Warning for minimizing Earth resistance:

Remove Oxidation on joints and joints should be tightened. Poured sufficient water in earth electrode. Used bigger size of Earth Electrode. Electrodes should be connected in parallel. Earth pit of more depth & width- breadth should be made.

Renown Electrcal System Pvt. Ltd. Mobile: +91 8920507272 Phone: 01204542468 Email: sales@renownpower.com Website: https://renownpower.com Address: E-58 Second Floor Sector-3 Noida, 201301

what is earthing in electricity