Monday, August 29, 2016

What is Earthing System and How Earth System Works for Protection

In electrical technology and electrical maintenance work, the most important thing is protection and safety and earthing is one of them. In this post is about what is earthing system or grounding. As you know that In single phase and three phase wiring we have a wire which is green or green plus Yalow and which connection is with electrical machine body which is called earthing but why this is important and how it's work. To clear these question from minds i am writing this post.
As i told in my above words that protection and safety is important in every work and when we talk about those works which is related with electricity power, the dangerous is very big then other works. Every one now that electricity is danger and but in world if some thing is dangers and make problem but every one agree with this that every problem have a salutation. In electrical works we can not say 100 % that we can make people completely safe from electrical shocks and accidents. But if we follow some protection roles and also do work with complete safety roles then we can stop these accidents  more then before.

What is Earthing System or What is Grounding System

Most electrical appliances, machines and motors body are made from the steel, these bodies are insulated to make safe but a Small mistake can case of big accidents. Due to this we face accidents in which many lost lives and money. The necessary is that to protect and safe him self from these accidents or do the right work which can stop these accidents. For that we do connection between electric machine steel body and earth by using a thick wire which is called earthing system.
Or we can said that the connection between electric appliances steel body and earth is called earthing system.o

In this process a steel or copper plate is buried in earth which we known with name of earthing plate and cooper wire is connected to the earthing plate. This wire connect to electrical machine body or frame to make a connection between machine body and earth. This is called earthing system or grounding system.

Import acne Of Earth / Grounding System in our lives 

All electrical machine or appliances insulated but if this insulation remove or hot or phase wire connect the machine body frame then some quantity of current live his right way and start flowing to the machine steel body which is called leakage current. In this case the workers which working on these machine can fell or get a big electric shock which may case of injuries or deaths.
But if we make a link between electric machines body and earth then the electric current flow through the machine steel body to earth and the human life safe from electric shock. In this process the electric current flow to earth instead human body because the resistance of earth is low contest a human body. The electric current flow always select way in which have a low resistance. And we can safe him self from a Strong electric shock.

How earthing system is working for protection of electric shock

In earthing connection we make a link between electric machinery by electric wire (which we called earth wire) with earth. The connection of earthing is that we  connect the earth connection wire to the metal body of electric machine which we connect which connect to earth. The connection of earth and machine by using the a conductor or electric wire is called grounding or earthing.
As you know that electron flow is called current and current always chose those way for flow which have low resistance.

So what happen when we did not do the ground connection to electric machine. When we did not do this connection and in case machine have faulty or the phase (line wire) connect to the machine body or the the machine is internally short circuit. So the phase current always try to flow to ground and when some one touch the the metal body of this faulty machine , he fell a big electric shock and which may make case of a big injury or death. In this case the phase current use the human body as conductor and start flow from human body to the ground. If that person stand on insulator type of surface and have no link with earth then by touching this faulty machine nothing happened.
So if we connect the a earth wire to the machine body then the phase current start flowing from metal body to the earth my earth wire.
The resistance of earth wire is low from a human body and as i told in my above words that electricity or electric current always flow and chose those ways which have low resistance or in which the current flow can move easily,

Let take an example. In the below example diagram i shown protection of shock in case of earthing system.
earthing system diagram

In the above earthing system diagram i shown incoming supply from supply substation which 220 volts of Alternating current supply. So the neutral wire direct goes to the machine (refrigerator) and phase wire is connect to a 10 ampere fuse and from the fuse it is connected to to machine. The substation is an transformer which secondary connection is in star (Y connection) and on star point a earth wire is connect. So machine have a fault to frame and the phase current start flowing from the frame to earth and this current goes to neutral point of substation through the earth and it's make a strong short circuit which start the over current flow and due over current flow the fuse will be burn or melting.
One thing more in case of installing high ampere fuse or circuit breaker, or connecting machine to low quality earthing system ' the fuse will not melt and when a person tech the machine, the fell a small electric shock or earth leakage current but if the earthing system is too week or the earthing system is high resistance earth then this earthing system can not protect you from electric shock accidents.