In some circumstances, you may need electricity but only have access to the phase wires of an AC main; if the neutral wire is not available, you need a neutral wire to use electricity for lighting a lightbulb or other electrical device. As you may already be aware, the earth can be used just like a regular neutral wire.
But the question is, how does this work? Does the earth contain wires? We will learn more about that in this chapter, how exactly earth works as neutral.
Before we begin, we should be aware of the fact that only star connections in the AC system use neutral, making them suitable for using neutral as earth. However, the delta system is a system that does not use any neutral point and also cannot work with earth wire.
This all happens because of the charge, which can be positive or negative. Positive or negative charges are not only attracted to negative or positive charges; they also attract neutral charges.
Okay, let’s get going. Starting with the planet Earth, the surface of Earth is neutral in terms of charge; you can say it is zero volts or neutral, which means no positive or negative charge will be present.
Voltage flows from a higher to a lower potential, which can be negative too. For illustration, if the cloud is positively charged, let us say 10000 volts, it will go and strike the surface of the earth during a thunderstorm, and if it is negatively charged, let us say -20000 volts, it will still flow toward the ground.
Electrical Current always flows if there is a difference in the voltage. This is why lightning will always be attracted to the surface of the earth because the earth is neutral, or has zero volts.
Pretty much every static or dynamic current tries to go to that earth point or neutral point; that happens because the electrons want to be stable, so they tend to attract toward the low potential.
In power plants, the neutral wires are always connected to the earth, and they can also provide a reference to zero volt, or, in other words, maintain zero volt. Doing this will make sure that the system will not have a floating voltage. Floating means that a system is not referenced to the earth and may have a different potential charge than the earth’s surface
But as soon as you connect the neutral point to the ground, the system creates a link to the earth, and the system will no longer be in a floating state.
To understand this in a basic way, let’s take a simple example. Suppose the earth is a piece of iron, and any charge is like a magnet. If you put the magnet near the earth, it will be attracted to the ground. You know magnets have plus and minus poles, but no matter which pole you use, plus or minus, the magnet will be attracted to the earth or iron.
About the same way electricity flows from higher to lower potential.
Let’s take another easy example of hot or cold water. If you heat or cool down the water and put that water in the open air, the hot or chilled water will match the temperature of the surrounding air. This happens because the water wants to be stable in the environment, so it shares energy with the surrounding environment and stabilizes.
If you want to do a very simple experiment, you can use a desktop SMPS power supply. There are numerous wires such as 12 volts, 5 volts, 3.3 volts, and even voltages in the negative range such as -12 volts.
If you measure voltage between 12 volts and 5 volts, the multimeter will show 7 volts because there is a difference of 7 volts. Same way, if we measure voltage between -12 volts and +12 volts, there will be 24 volts!
If you measure a ground wire and a -12 volt wire, there will be 12 volts, but the ground wire will be positive while the -12 will serve as the negative wire.
This is getting interesting, isn’t it? We will read about this in another chapter, as it’s a very important topic.
In the case of a delta system, there is no neutral wire, so the system is not grounded and there will not be any neutral wire. In such systems, earthing cannot be used.
On the other hand, the batteries use chemical energy, so their return wire must be connected to the positive wire in order to work, as the return wire is important for the chemical reaction. Thus, batteries can’t be earthed.
The concept is very easy, but it’s not often explained properly, so we face problems understanding such fundamentals.
