In electrical technology and electrical maintenance work, the most important thing is protection and safety and earthing is one of them. This post is about what earthing system or grounding is. As you know In single-phase and three-phase wiring we have a wire which is green or green plus Yalow and which connection is with the electrical machine body which is called earthing why this is important and how does it work? To clear these questions from minds I am writing this post.
As I told in my above words that protection and safety are important in every work and when we talk about those works which are related with electricity power, the danger is very big than other works. Everyone now that electricity is a danger and but in the world if something is dangerous and makes a problem but everyone agrees with this that every problem has a salutation. In electrical work, 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 than before.
What is Earthing System or What is Grounding System
Most electrical appliances, machines and motors body are made from steel, these bodies are insulated to make them safe but a small mistake can cause big accidents. Due to this, we face accidents in which many lost lives and money. The necessary is to protect and save himself from these accidents or do the right work which can stop these accidents. For that, we do a connection between the electric machine’s steel body and the earth by using a thick wire which is called earthing system.
Or we can say that the connection between an electric appliance’s steel body and the earth is called earthing system.
In this process, a steel or copper plate is buried in the earth which we know by the name of earthing plate and cooper wire is connected to the earthing plate. This wire connects to the electrical machine body or frame to make a connection between the machine body and the earth. This is called earthing system or grounding system.
Import acne Of Earth / Grounding System in our lives
All electrical machine or appliances are insulated but if this insulation remove or hot or phase wire connect the machine body frame then some quantity of current lives the right way and start flowing to the machine steel body which is called leakage current. In this case, the workers which work on these machines can fall or get a big electric shock which may cause injuries or death.
But if we link the electric machine’s body and the earth then the electric current flow through the machine’s steel body to the earth and human life is safe from electric shock. In this process the electric current flow to the earth instead human body because the resistance of the earth is low contesting the human body. The electric current flow always selects ways which have low resistance. And we can save him from a Strong electric shock.
How earthing system is working for the 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 the electric machine which we connect which connect to the earth. The connection of the earth and the machine by using the conductor or electric wire is called grounding or earthing.
As you know that electron flow is called current and current always chose those ways for flow which have low resistance.
So what happen when we did not do the ground connection to the electric machine? When we did not do this connection and in case of the machine has faulty or the phase (line wire) connected to the machine body or the machine is an internal short circuit.
So the phase current always tries to flow to the ground and when someone touches the metal body of this faulty machine, he fell a big electric shock and which may make cause a big injury or death. In this case, the phase current uses the human body as a conductor and starts flowing from the human body to the ground.
If that person stands on an insulator type of surface and has no link with the earth then by touching this faulty machine nothing happened.
So if we connect the earth wire to the machine body then the phase current starts flowing from the metal body to the earth’s earth wire.
The resistance of earth wire is low from the human body and as I told in my above words electricity or electric current always flows and chose those ways which have low resistance or in which the current flow can move easily,
Earthing system Diagram
Let’s take an example. In the below example diagram, I show protection from shock in the case of earthing system.
In the above earthing system diagram I have shown the incoming supply from the supply substation which is 220 volts of Alternating current supply. So the neutral wire direct goes to the machine (refrigerator) and the phase wire is connected to a 10-ampere fuse and from the fuse, it is connected to the machine.
The substation is a transformer whose secondary connection is in the star (Y connection) and on the star point, an earth wire is connected. So the machine has a fault to frame and the phase current start flowing from the frame to the earth and this current goes to the neutral point of substation through the earth and it makes a strong short circuit which starts the over current flow and due over current flow the fuse will be burn or melting.
One thing more in the case of installing a high ampere fuse or circuit breaker, or connecting the machine to a 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 weak or the earthing system is high resistance earth then this earthing system can not protect you from electric shock accidents.