Earthing System: The All round Safety Mechanism

Good day Steemians, trust we are having a good week. Good to always find you guys on my blog, I duly appreciate the comments and responses on my posts. The previous were science-related based on what I learnt over the weeks which I felt I could share with beautiful people on here to acquiring the knowledge. I wanna appreciate the #steemstem & #stemng and the wonderful people around. I've learnt alot lately engaging more in the community. May God bless you all..!

Today, I would be delving back into the world of engineering. Stay with me, we wouldn't be diving too deep but deep enough to keep you informed and possibly a bit more grateful for the gifts of technology.

In the world of Engineering generally, safety is key and an important concern to the field. Adequate protective devices are employed in the field for protection of lives, service personnel and equipments. The freedom from harm or danger is very important to service engineer and a big subject in the engineering sector.

^{Webomedia Creative Commons BY-SA 3.0 License: Earthing}

In the electrical engineering sphere, there is always an encounter with electricity in one way or the other. If proper handling is not done with electricity, i don’t think i should spell the consequences to you. Or if you don’t mind, let me tell you a story about Jake. Jake is a very adventurous guy and he likes trying out new things daily. One day, he decided to put one of his age long curiosity to test and as soon as he put his finger into a socket that is supplied with electricity and WHOOSH!! Jake became ELECTRO MAN!!

Well, i expect you to know that was a joke. One of the safety mechanism that are applied to electrical systems is the earthing system. Join me as we have a look.

Earthing system is one of the mechanisms employed in electrical engineering to ensure safety is provided for lives and the power equipments. Have a swell time reading as I take you through a beautiful ride of the significance and principles of earthing systems in electrical engineering.

The world earthing can be found popularly being referred to as grounding. Earthing is basically an electrical system which refers to the process of discharging leakage or stray flow of electric charge to the body of the ground (earth). Earthing is a mechanism which is used to protect the various parts of electrical installation as well as service personnel against damage in case the system insulation fails at any point in time. Electrical installations are designed to be safe providing adequate protection schemes to ensure safety of the installation, animal and human lives.

Safety is a substantive interest when working with electricity. No doubt everyone tends to be extra careful while dealing with electricity, nobody want to die you know. The possibility of an electric shock is always present while working with electricity, so caution should always be taken

Before dwelling more on earthing mechanism, let's take a slight dig at the effects of current on human body.
Electric shock is caused by passage of current through the body when a part of the body comes in contact with a voltage source. Severity of electric shock depends on the amount of voltage and the path the current takes through the body. Also, the current through the body determines which tissue or organ the will be affected.
Severe electric shock may lead to heart paralysis and tissue burn which may claim one's life. Therefore, safety precautions should properly be taken while dealing with electricity.

Have you ever wondered why we have the earth pin of a 3-pin plug longer with larger cross sectional area? Safety it is for!
When the plug is attached to a socket, the longer pin goes in first discharging all the leakage or stray current before the other two goes in protecting the equipment and also comes out last when unplugged. The earth pin is basically used for discharging leakage or stray current during the process of connection and disconnection.

The earth pin of the plug is based on the relation:
R=ρL/A where;
‎R= Resistance
ρ=Resistivity
L=length
A= Cross sectional Area

As the cross sectional area increases, the resistance decreases. The low resistance of the pin allows it to accommodate more passage of discharge of leakage current through it.

The need for protective mechanisms in the field of electrical engineering cannot be overemphasized as adequate safely of lives and electric power equipment is required. Earthing thereby is a form of system protection to protect lives and power equipments from accidental conditions which may cause damage to lives and properties.

Objectives of Earthing system

• To convert to earth, any leakage of electrical energy to the metal works without hazard to personnel or equipment

• ‎To protection various parts of electrical installation in case insulation of a system fails at any point.

• To protect building and power equipments from lighting

• ‎To prevent the risk of fire in electrical installation

• To serve as return path for leakage current

How is Earthing Achieved?

Like I've explained, earthing is a process of connecting all metal works (other than power conductor) to the general mass of the earth with the aim of converting to earth any leakage of electrical energy to the metal works without hazard to personnel or equipment.

An earthing system thereby consist of two parts:

1, A low resistance conductor bonding the metal works
2, An electrode buried in the ground

The main earthing components are the circuit protective conductor (CPC), the earth conductor and the earth electrode.
The CPC is the conductor that connects all the metal works to the earth, the earth conductor conducts the circuit protective conductor to the earth electrode and the earth electrode is the rod which makes the final connection to the general mass of earth.

A characteristic of the earth electrode is that it's resistance must be very low so that fault current through it is high. It is usually made of steel with good corrosion resistance.

In the application of Earthing mechanism, a low resistance path is required which is determined by the resistance of the soil. Moisture content, soil temperature, concentration of soluble chemicals among others are factors that affects soil resistivity. Where grounds are found rocky having high resistivity, the only way to obtain a low resistance path is by installing a grid of buried conductors. Also where earthing is found difficult, some form of chemicals may be mixed with the top soil or spread over the surface, it percolates downwards and reduces the resistivity of the soil.

Ways of Improving Earthing System

Earthing system can be improved by the use of Ground enhancing Material (GEM). They are use to improve or enhance conductivity. They are generally low resistance, non-corrosive material that improves effectiveness especially in area of power conductivity such as mountain tops, rocky grounds etc.

Other ways of Improving earthing system in includes:

1, introduction of multiple earth electrodes
2, Increasing the dept of earth pit
3, Addition of addictive such as manure to the earth pit in order to improve the ground conductivity
4,Introduction of earth grid/mat

Other Ways of Protecting Electrical Installations

• The Lightning Arrester System:
  The discharge of electrons from atmosphere during thunderstorm and lightning is capable of causing damage to electrical installations if not proper protected against. Lightning protection is achieved by providing a low resistance path between the atmosphere above a structure and ground so that the lightning discharge can take place without causing dangerous effect on electrical installations and equipments.

You must have seen a slim rod standing right on a rooftop, that's a lightning arrester which protects the building from lightning discharge. It is connected alongside other components to achieve the protection.

• Fire Alarm System:
  This is a type of protection system found within the building for protection of electrical installation. This is installed in the building to provide information on smoke that could result in fire for early detection but not to prevent nor fight it.

• Circuit Breaker:
  This is a mechanical devices capable of breaking electric circuit under fault conditions.

• Fuse:
  This is a device which trips or melts on arrival of excess current on the electrical equipment

• Surge Diverters:
  These are also electrical devices capable of diverting surge current or excess voltage to the ground

The need for adequate earthing system are as well employed in the electric power system. Power are transmitted via power lines from generating station to load centres. Fault do occur along the line which may cause abnormal operation of the system which may lead to expensive damage to the equipment. Hence, adequate system protection is provided. Power switch yards, transformers and overhead lines are adequately protected against lightning and other forms of fault.

Method of Earthing for Power System

• Power SwitchYard Earthing

Earthing method for a power switch yard is done by burying an array of electrodes in the ground which forms a earth mat in an horizontal arrangement. The equipment bodies, structural steel works, towers etc. all found in the switchyard are all earthed by connecting to the earth mat.

• Power Transformers

Power transformer is earthed by preparing an earth mat, whereby a coal-salt mixture is added to create a low resistance for fault current to flow. The general earthing point of the transformer provided on the body is being connected to the earth mat. The neutral point of the transformer is connected to the earth mat so that potential of the transformer with respect to earth is stabilized.

• Overhead Transmission line

If you've ever noticed two parallel tiny wires running ahead of a high tension power transmission line, then you have seen what overhead transmission line grounding looks like. These two sky wires are what forms the overhead grounding mechanism.
Overhead Transmission line are earthed by burying an array of electrodes in the ground forming an earth mat majorly of copper conductors. They are connected such that their terminals are brought out and terminated to the overhead grounding wire so as to prevent direct lightning strikes to the conductors carrying current. This earthing of transmission line is achieved by providing the earthing to the overhead ground wires at certain distances along the transmission line.

CONCLUSION

The need for protective mechanisms in the field of electrical engineering cannot be overemphasized. Adequate protective system is required to protect lives and equipment from accidental conditions which may cause severe damage.
Earthing system and other forms of Protection mechanisms are employed in electrical engineering to ensure safety is provided for lives and the power equipments.

Thanks for stopping-by here today again! Do have a stress-free week!

References

• Adebisi, O. I. Lecture on Electrical Service and Energy Utilization.
  Federal University of Agriculture, Abeokuta

• B. L Theraja & A. K. Theraja [S.Chand]. A Textbook of Electrical Technology

• Circuit Globe

• Electrical Engineering Portal

• Energy Guide

• Raychem

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