WHAT IS ACTUALLY GROUND AND NEUTRAL IN TRANSMISSION SYSTEMS?

       Actually most of them have a common question in their mind about what is actually a ground and what is neutral in transmission system,  in this article I have tried my best to explain about these topics.
       Before going to the topic let us learn individually about these terms:

NEUTRAL:

       At first we are going to see about the NEUTRAL,  Actually a neutral is termed as the return path or closing network of an A.C transmission system or circuit which is designed to carry current in the normal conditions.  This current actually happens due to the imbalance of the loads and due to harmonics, i will soon post a article about these!  There may be also many reason behind the current flowing in the neutral wire but the magnitude of this current is actually lower than the phase current in some case it may be twice that of phase current. Thus neutral wire is not passive and safe to touch, touching neutral wire may cause minor injuries in some case fatality(i am just kidding but severe burns since A.C flows through it),thus it is also considered as an active circuit with charges.  This neutral wire is finally given to the ground by connecting to the earth's crust by rods, to make the second terminal of the neutral wire at zero potential. Since presence of potential at the neutral terminal resist the current flow through the phase.

EARTH OR GROUND:

       To know about the grounding click this text to see my full article about grounding or earth. Earth or Ground is for safety concerns against leakage or residual currents on the system via least resistance path. While phase and neutral is connected to main power wiring, earth may be connected to body of equipment or to any system which in normal condition doesn’t carry current but in case of some insulation failure, is supposed to carry some minor current.

        This current is not directly coming from live or phase wire, but is from secondary links which was not in touch with live system in normal condition. This current is usually much lesser than main line current or phase current and mostly is in order of mA. But this leakage current is good enough to kill someone or may risk fire. Such current are being provided a low resistance path and sent to earth via earth wire.
          Because of the difference in application we never mix grounding of neutral and earth. However both are made grounded (of-course the process may be different). If both will be mixed then the earth wire which is not supposed to carry any current in normal condition , may have some charges across and will become hazardous.

PRACTICAL EXPLANATION:
         Consider a transmission system in which the A.C is generated in the power production plants.  These electricity should be distributed to us, so practically it require two transmission line to complete the circuit since the current flows through the closed loop.  Initially these kind of transmission is done(ie before introducing the term ground). Though this method is simple the two long cable cost is very much higher so engineers made an alternate solution.
           Some electrical genius thought that since earth behaves as a perfect zero voltage why can't we use the earth's crust i.e the ground as a conductor which is used to close the path, Later it is proven that ground is the perfect conductor.  Thus the concept of earth line is born. Since it used one single cable they were proud as they reduced one wire lol.

          However we are now using a three phase distribution system.  So the above single phase diagram needed an re-modelling.  Another a genius come up with this design.  Since the transmission lines reach the distribution transformer present in your local grid,  The delta to star transformation of the power is done.  I will also write an article about star to delta network stay tuned.  At the right centre of the star system it is connected to the earth thus connecting the power plant to the transformer thereby closing the circuit.  This earth line is extended and a new line is introduced called as neutral is introduced for household transmission systems.  Thus from distribution transformer there is no earthing but it has two lines one is phase and other one is neutral.  The L-N lines will go to our houses.  Notice that the transmission has only live lines whereas the distribution line has both phase and neutral. Thus the household sockets are connected in parallel to reduce the loss of voltage and the extra pin called as individual household grounding wire is introduced, To know about this wire and to check your house whether your house is grounded click this text to go to my article about this. I hope this para explains well lol if not dont feel shy to ask your doubt in comment!
           If we observe our power sockets in our house there might be three pins for driving heavy loads and electronic components.  The bottom two are the phase and neutral and the top one is for safety called as ground.  In normal cases when the load is connected the current flows from the phase to the neutral.  But in some special cases if there may be any leakage or alternative path for the current to flow through earthing will come in action eliminating these leakage current.  Though human body will not be electrocuted since we have MCB, ELCB OR RCCB to protect us nowadays.


IN CONCLUSION:
  1. As for we consider the power generating side the neutral and earth have the same common point.
  2. Neutral or earth will act as the return path of the supply.
  3. From the distribution side the neutral lines are separately introduced which is then grounded separately.
  4. Neutral in this case will return the path of the supply.
  5. Earth is available but normally no current will flow in that unless any leakage occurs.
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