NEUTRAL represents something which is; at free state, Something which is without load. Neutral can be described as a home state for the system.
Similarly in AC power, Neutral is low potential return path for current; back to the Source. Electrical neutral originates from the winding connections of its sources like transformers and alternators.
Neutral originates from the mid point of STAR winding connection. In ideal conditions, neutral contains zero potential. But in Actual conditions; neutral’s potential depend upon the load balancing across the star winding connections. Practically, It is quite difficult to balance the loads equally on star winding connections that’s why some potential exist on neutral.
A GIF shows the working of Single phase Load
ORIGIN OF NEUTRAL
Winding’s overall configuration made with multiple coils by arranging these coils in symmetry; in particular manner. There are basically two types of winding connections that is; Star & Delta.
STAR WINDING
A Coil; which is the part of the winding; Contains 2 nodes or 2 ends. If 3 coils been arranged in such a way that each coil’s end get connected & a Junction been made than winding configuration becomes STAR which is also known as Y(wye). The mid point of Y configuration represents Neutral while rest of 3 terminals represents potential nodes.
A potential difference between potential node & neutral is known as phase voltage While a potential difference between two potential nodes is known as line Voltage.
Clearly explained in a GIF above.
GIF elaborates STAR & DELTA Winding Connections
DELTA WINDING
IF 3 Coils been arranged in such a way that all the 3 coils get connected in series manner & then each node of the coil been brought out such that 3 terminals get remains; Than that connection represents delta connections.
Since there is no mid point, no neutral in this winding connection which means there is no phase voltage only the line voltage exist in Delta winding.
Clearly explained in a GIF above.
Since STAR winding connections contains the Neutral that’s why Distribution Transformers been designed with primary in delta While Secondary in Star winding connections.
WINDING CONNECTIONS OF DISTRIBUTION TRANSFORMER WITH VOLTAGE RATIO 11KV/415V
Distribution Transformer’s Winding connections | Primary Delta While Secondary Star
NEUTRAL’S LOGO & COLOR CODE
Term neutral belongs to AC quantity Which is been represented with English alphabet letter ‘N’. ‘Black’ is the standard color code for Neutral wire.
Line & Neutral symbol printed on digital device
WHY DO WE NEED NEUTRAL ?
Before Answering this question, We should know about the potential difference , First !
An Electrical load works when current flow through the load & current only flows When there is potential difference across the load. Only Single potential can’t do anything.
Potential difference in AC represent the differences of magnitude & phasor in between the two nodes.
A presentation which shows potential difference in between the two nodes.
UNDERSTANDING THE POTENTIAL DIFFERENCE WITH 2 EXAMPLES, NEXT-
” A gif of 5 wires power supply been shown below Which includes 3phases, 1neutral & 1 Earth. Having the line voltage of 415VAC.”
Line Voltage represents voltage between two phases.
Phase Voltage represents voltage between phase & Neutral.
A GIF shows Voltmeter detecting different potential nodes
According to GIF above :
Line Voltage is 415VAC
Phase Voltage is 240VAC (Neutral=0Volts)
Voltage difference between phase & Earth is; 240VAC (Earth=0Volts)
Voltage difference between 2 same phases is; zero.
” A Bird freely moves on High tension line But We; While standing on Earth; Bird get electrocuted from medium voltage supply. “
Bird on a high tension line represents a single potential phenomenon which means no current flows through the bird.
But While standing on this earth & getting in contact with zero potential(earth), represents a phenomenon of minimum(zero) potential. While standing on earth; We are already under the influence of low potential, There is only need of potential. When any body part get in contact with potential, Current finds a path towards the earth through the feet.
For a particular single phase load with having a rated voltage of 240VAC, A Single phase power supply with 2 nodes is required. In which One is potential node of 240VAC & another second one is Neutral. But we can also run the same load with 2 phases if there is line voltage of 240VAC which means each phase contains a voltage of 240/√3=138VAC.
So its been concluded that without a neutral; Any load can get run with two phases if line voltage is equal to the rated voltage.
NOW; BACK TO THE QUESTION, WHY DO WE NEED NEUTRAL ?
Reason 1. For a potential difference; We need minimum 2 wires. If there is no neutral than there must be 2 phase system. If 2 phase system is utilized than except the earth wire; Each wire in the power board contains the potential.
Every connected load contains a potential; Even the switch remains in off position scenario. Which further increases the Risk of leakage. On the other hand, In single phase connection when switch is in off position only neutral remains present in the load, No potential. Which means No risk of leakage.
Reason 2. Fault tracing is quite easy in 1 phase supply rather than 2 phase supply because it is difficult to distinguish the phases in 2 phase system.
Reason 3. Single phase system can easily be balanced on 3 phase transformers In comparison with 2 phase system.
NEUTRAL BALANCING
Stable & balanced voltage is not only important for the proper functioning of appliances But It also increases the useful life with maximum efficiency. Most of the home appliances & gadgets are available in single phase That’s why neutral should be sound & perfect under the specified range.
As Discussed above, Neutral remains at lowest potential until all the 3 phases are perfectly balanced which is quite difficult in this practical world. To remove this uncertainty, Neutral node should always be connected with an individual EARTH. For best practices, 2 EARTHS been connected with neutral so that Neutral always get remains at lowest potential.
A Diagram shows Neutral balancing through Earthing
Hope, You like the post. If you have any doubt, Suggestion or query Please do comments !
