ELECTRODE EARTHING : A new technology.

“ASHLOK” Safe Earthing Electrode.

Earthing is of utmost importance for the safety of a plant, equipment, property and human as well as animal life. In the absence of a well-designed effective earthing system, earth fault conditions may lead to tremendous loss of property and lives. Earthing is fundamental to most of the practices for achieving safety. The earthing system must provide a direct route to the soil for fault current whilst minimizing touch and step potentials. The secondary function is to help mitigate disturbances and serve as a common voltage reference for sensitive electronic equipment. However, with greater use of sensitive electronic equipment, particularly in Software Industries & Telecom Sectors, there is a growing awareness of the importance of the secondary function of the earthing system. This is leading to a consensus of opinion that the earthing system must be designed as an overall system such that it fulfills the safety and performance requirements.

The main objectives of earthing are as follows -

1. To ensure safety of life and property from hazards of electric shock and electric fires.

2. To ensure that system voltages on healthy lines remain within reasonable limits under fault conditions thereby preventing insulation breakdowns.

3. To provide a low impedance path to facilitate the satisfactory operation of protective devices under fault conditions.

4. To minimize arcing burn downs as in an earthed system arcing fault would produce a current in ground path thereby providing an easy means of detecting and tripping against phase to earth arcing fault breakdowns.

5. To provide an equi-potential platform on which electronic equipments can operate.

6. To provide an alternative path for induced current and minimize the electrical noise in cables.
The earthing system consists of conductive material above ground (bonding conductors etc.), metal electrodes within the soil and the surrounding soil itself. Each of these will contribute towards the overall impedance value. However, it is important to recognize that the characteristics of the soil strongly influence the earthing system performance. The most important characteristic of the soil is its resistivity, which is measured in Ohm-meters.
An earth pit may comprise of several large pipes inserted vertically into the soil. They are bonded together and surrounded by low resistivity material.


EARTH ELECTRODE :
The earth electrode is the component of the earthing system, which is in direct contact with the ground and thus provides a means of releasing or collecting any earth leakage currents. In earthed systems, it will normally be required to carry quite a large fault current for a short period and so will need to have adequate mechanical and electrical properties to continue to meet the demands on them over a relatively long period, during which actual testing or inspection is difficult. The material should have good electrical conductivity and should not corrode in a wide range of soil conditions. Materials used include copper, galvanized steel etc.
Copper or Galvanized steel is generally the preferred material. Aluminum is sometimes used for above ground "bonding,” but most of the standards forbid its use as an earth electrode, due to the risk of accelerated corrosion. The corrosive product - an oxide layer - is non-conductive, so could reduce the effectiveness of the earthing.
Backfill
In all cases, the backfill medium must be non-corrosive, be of a relatively small particle size and should, if possible, help to retain moisture. More often than not, the previously excavated soil is suitable as a backfill, but should be sieved to remove any large stones and placed around the electrode, taking care to ensure that it is well compacted. The soil should have a pH value between 6.0 (acidic) and 10.0 (alkaline). Normal, stiff clay is not a suitable backfill material as, if heavily compacted; it may become almost impervious to water and could remain relatively dry. It may also form large lumps, which do not consolidate around the rod.
Materials, which should not be used as backfill, include sand, coke-breeze, cinders, and power-station ash, many of which are acidic and corrosive.
Requirements of the Earthing System :
The function of the earthing system is two-fold.
1. To provide a low enough impedance path, via the earth conductors, back to the supply source so that in the event of a failure to earth of a live conductor, sufficient current will flow safely along a predetermined route to enable the circuit protective device to operate.
2. To limit the potential rise on all metalwork to which persons and animals normally have access, to a safe value under normal and abnormal circuit conditions. The bonding together of all normally exposed metalwork, such as gas, water, central-heating pipe work etc., and the connection of that bond to the earth terminal, will prevent the possibility of a dangerous potential difference arising between adjoining pipe work under both normal and abnormal conditions.

Considering all the above “ASHLOK”, after a consistent R & D work of more than a decade has developed a new earthing technology which not only takes care of the above but also literally maintenance free earthing system. Unlike the conventional earthing system, these earthing systems do not require the use of salts, charcoal etc, and have a very long corrosion free life.

Method of Electrical Earthing :

The general pipe earthing practice followed World over is that, in this a perforated G.I./C.I. Pipe is placed vertically in side the earth and layers of Sand, Salt, Charcoal etc. is put around the Electrode. On the top of the Pipe Electrode, a funnel is provided for watering purpose, so that enough moisture remains around the Electrode since moisture is very much essential for any type of Earthing to work. When water is poured from top of the Electrode through the funnel, as water spreads out through the hole, the surrounding Salts, Charcoals etc. comes in through the hole & the holes get clogged. The result is that the corrosion of the pipe starts inside and outside simultaneously and the pipe is cut with in two or three years and purpose of earthing is defeated.

The use of water, salt etc. is required for lowering the soil resistivity, as the low resistive soil is good for earthing purpose. However, it is equally true that “Lower the soil resistivity, better the earthing BUT Lower the soil resistivity, Higher the corrosion effect”

Here the “ASHLOK” Safe Earthing Electrode (SEE) serves the purpose effectively. In the ASHLOK SEE, there are two pipes of different diameters. The smaller dia. pipe is inside the bigger dia. pipe and the annular space between the two pipes is filled with a special conductive compound, which resists the corrosion. The earth electrode is hot dip galvanized to enhance the life of the earth electrode particularly the outer shell which is susceptible to corrosion (depends on the soil conditions). Only the inner shell (main electrode) of the electrode is protected by anti corrosive compound. As the outer shell of Earthing Electrode is not perforated, there is no need of providing a funnel on top of the Electrode. Here the water is poured around the Earthing Electrode, not inside the Electrode as is done in conventional Pipe Earthing.

Installation Method

Once installed properly the ASHLOK Earthing Electrode will give a very good earth resistivity value compared to the conventional earthing and since this earthing electrode resists the corrosion, the earth value will remain same with out much fluctuation. This earthing system does not require any maintenance in normal soil conditions except few buckets of watering during very hot summer season. If it is installed properly as per our specification then it will show better result than conventional earthing system for many years. However, it is important to note that characteristics of the soil play a major role in determining the earth resistance value and the factors that determines the characteristics / resistivity of the soil is given below.

The earth resistance value (Ohmic Value) of an earth pit depends on the soil resistivity.

FACTORS DETERMINING SOIL RESISTIVITY

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

2. Effect of Moisture on Soil Resistivity: Moisture has a great influence on resistivity value of soil. The resistivity of a soil would be determined by the quantity of water held by the soil and the resistivity of the water itself. In other words conduction of electricity in soil is through water, which means that phenomenon is electrolytic. It is to be noted that resistance drops quickly to a more or less a steady minimum value at about 15% moisture and thereafter, increase in the wetness of the soil has little effect.

3. Effect of Dissolved Salts in Water: Since the resistivity of the soil depends on resistivity of water, which in turn depends on amount and nature of salts dissolved in it. It is to be noted that quite a small quantity of dissolved salt can reduce the resistivity considerably. A small quantity of salt 1 to 2% by weight of moisture drops the resistivity by 80% as the concentration is increased; the moisture tends to a steady low value.

4. Effect of Temperature on Soil Resistivity: Soil resistivity increases sharply with decrease in temperature below 0°C. At -15°C the earth resistance was found to be over ten times at 0°C. This signifies the need of burying the electrodes sufficiently deep below the frost level especially in regions where low temperature below 0°C is experienced.

5. Effect of Grain Size and its Distribution: Grain size, its distribution and closeness of packing are also contributory factors, since they control the manner in which the moisture is held in the soil.

6. Effect of Seasonal Variation on Soil Resistivity: We have observed that presence of moisture in the soil is the most important element in determining its conductivity. Conditions, which increase or decrease the distribution of the moisture content in the soil result correspondingly in an increase or decrease of the conductivity. It is thus anticipated that resistivity of the earth will undergo variation with seasonal changes. Field experiments have indicated seasonal variation of resistance up to 60%.

7. Effect of Current Magnitude: Soil resistivity in the vicinity of ground electrode may be affected by current flowing from the electrode into the surrounding soil. The thermal characteristics and the moisture content of the soil will determine if a current of a given magnitude and duration will cause significant drying and thus increase the effect of soil resistivity.

PROPER INSTALLATION METHOD: The installation method is pasted on each & every earth electrode supplied by us. However, the ASHLOK Safe Earthing Electrode can be installed by any one of the following methods depending on the soil condition.

Normal Soil:
Make a bore of 8” to 10” in diameter manually up to the electrode length (2 Mtr or 3 Mtr). Put a little quantity of Back Fill Compound (a layer of min. 3 to 4 inch) in side the pit and drop the electrode exactly in the center of the pit. Now mix the soil that has been dug out with the B.F.C. like sand & cement. Now pour the above mixture in small quantity in to the pit followed by water and remove the trapped air inside the pit by poking a rod in to the mixture repeatedly. Repeat the above exercise till the pit is completely filled up. Pour sufficient water so that mixture is in paste /mud form.Allow the pit to absorb the water and becomes compact. Test the earth pit and connect to the electrical circuit. Avoid excess watering. Do not hammer the earth electrode.
Sandy Soil:
Please make a big pit of 12’ x 12’ and 12’ deep; fill the entire pit with black cotton soil or normal soil, pour enough water so that pit is full with water, leave it for three days so that soil soaks up the water. You will notice that soil level has gone down and again top up the pit with soil & fill the water. Now after two or three days this pit is ready for earthing purpose and our earthing can be installed there by above described normal method, that will definitely give you a very good earth resistivity value. However, if the pit is filled with BFC mix soil then that will show better earth resistance value. These types of installations may needs regular watering after certain intervals that depends on the characteristics of the soil described in the “Factors determining the soil resistivity”. It is to be noted that more than one earth electrode may be required to be installed and connected in parallel to bring down the earth resistance value with in safe limits.

Semi-Rocky Soil:
If enough soil is there then earthing can be done by normal method otherwise that can be done by making a big pit as in case of sandy soil. Ours is a corrosion resistant, long life and almost maintenance free earthing system in normal soil conditions & if installed properly it will give better earth resistivity value than conventional earthing system. It is a Fit & Forget earthing system. However, these types of installations may needs regular watering after certain intervals that depends on the characteristics of the soil described in the “Factors determining the soil resistivity”. It is to be noted that more than one earth electrode may be required to be installed and connected in parallel to bring down the earth resistance value with in safe limits.



Measuring the Impedance of Earth Electrode Systems
Measurement of the Ohmic value of a buried electrode is carried out for two reasons: -
· To check the value, following installation and prior to connection to the equipment, against the design specification.
· As part of routine maintenance, to confirm that the value has not increased substantially from its design or original measured value.
ASHLOK’S Back Fill Compound (B.F.C.) is a specially developed compound, which is capable of absorbing and retaining the moisture for a long time, it reduces the soil resistivity, it helps in faster dissipation of fault current, least fluctuation of Ohmic value and it eliminates the use of Salt, Charcoal etc. around the Earthing Electrode.

It has low solubility, hence is not easily washed away, and has a low resistivity (approximately 5-10 Ohm-meters in a saturated solution). It is virtually neutral, having a pH value of between 6.2 and 6.9. It is naturally occurring, so should not generally cause environmental difficulties in use.

It assists in maintaining a relatively low resistivity over a long period of time, in areas where salts in the vicinity are dissolved away by water movements (rainfall etc.). However, the fact that the material is not easily dissolved will moderate the benefits achieved, since it will not permeate far into the ground. This means that the beneficial effect will be localized for say an area excavated around a buried electrode. This in turn means that the reduction in the resistance value of the electrode will not be dramatic but will be reasonably sustainable.
arthing electrode reduces with age.

Cost Comparison of ASHLOK Safe Earthing Vs Conventional Earthing :

The initial cost of the conventional earthing system may seem to be low as compared to the ASHLOK’s earthing system, but then, the conventional earthing system needs regular maintenance to keep it in a healthy condition. In spite of the maintenance there is natural decay of the earth pipe due to oxidation and after some period of time the earthing becomes useless. DUE TO THE PRESENCE OF SALT, CORROSION STARTS TAKING PLACE IN THE PLATE USED, THUS INCREASING THE RESISTANCE OF THE EARTH PLATE AND IN THE PROCESS DEFEATING THE PURPOSE OF PROVIDING A LOW RESISTANCE PATH FOR ANY FAULT CURRENT IN THE CIRCUIT. At this point of time we have to install new earth pits and this goes on and on, letting you spend more money in replacing the old earth pits with new one & in maintenance of the earthing system.

Apart from spending more money it is the disruption of the services due to faulty earthing system, which must be avoided in all condition because this results in loss of revenue.

On the other hand ASHLOK’s earthing system may have an initial higher cost than the conventional earthing system but unlike the latter, this earthing system does not require much maintenance, is CORROSION RESISTANT, is least affected by weather conditions and has a very very long life i.e. Fit & Forget.

From the above it is clear that conventional earthing is cheaper initially but if we take in to account the recurring expenses due to frequent maintenance & replacement of the earth pits, which is always going to be dearer with the time, then ASHLOK Safe Earthing Electrodes are the best available cost effective solution for a reliable, maintenance free & trouble free earthing system and thus the money spent on ASHLOK’s earthing are not an expense but an investment.

[ Key point : Earth value depend on the local soil resistivity.]


The ASHLOK Safe Earthing Electrode is the very latest in 'earthing' technology,
This will take the worry out of reaching those low resistances so often needed for transformer & generator earths...even in the most challenging conditions.


In essence, the ASHLOK Safe Earthing Electrode together with ASHLOK Back Fill Compound, chemically conditions the surrounding soil, so that even when the soil is dry the 'connection' to earth is kept in tact.
Benefits
Peace of mind that readings WILL be achieved
Performance is outstandingly consistent whatever the season
Safety assured
Hassle-free solution
Maintenance free
Applications
· Telecommunication Towers & Microwave Antennas
· Transmission & Distribution Systems
· Substation & Power Generators
· Computers & Data processing Centers
· Manufacturing Facilities & Refineries
· Generator earths
· Transformer earths
· Lightning protection earths in difficult conditions


RISK DUE TO SHORT CIRCUIT FAULT CURRENTS :
· 20+ fires a day are caused by faulty electrical installations
· Fires are 12 times more likely to be caused by faulty electrics than, say, by gas.
· 2000+ people are injured through electrocution every year.
· As per National Crime Records Bureau (NCRB) of India, around 15 people die every day due to electrical accidents, which account for nearly 3% of total accidental deaths.
· The majority of deaths, injuries and damage would have been prevented by an installation inspection.
· Older properties (10+ years old) are most at risk.
· The danger is increased, as it is usually out-of-sight, under floorboards, behind walls.

“ Let’s earth the EARTH for the future.”

TECHNOLOGY SYSTEMS.
LUCKNOW - 226012. [UP].
[Phn : 0933 510 1493 / 0933 577 98 33.]
(For inquary : ashokjoshi124@yahoo.com)