Ohh my god the way you explained.... Thank you so much

Thanks for adding actual subtitles for the Deaf

The actual reason there is no neutral on a transmission line is, If the line was run in a Y configuration over all to all smaller  distribution sub stations,, there would be many ground return paths, through each substation along the line. And the energy return to source station distribution would be reduced.  With the delta, no neutral configuration, all faults current is returned to the source station, through the earth ground and via the static/lightning line if equipped. To where there is fault current detecting equipment installed  trips out the  source of the transmission line. The fault current is returned to the source location to cut off the source. Like the breaker panel in your house , sort of. There is a ground source reference at every source transmission station. Transmission lines, some wired like Y configuration at the source station., but grounded at the source station only with sensing equipment on the ground. But exit in a delta. Some delta only stations have what's called a zig zag bank transformer or ground reference transformer. The CT's and VT's of the ground ref unit are connected to the protective equipment to shut down the line if there is a phase to phase fault or phase to ground (tree, downed conductor,car accident) issue.

Some notes. What you call "Star" is commonly known as Wye 'Y' configuration. It uses 3 phases with a Netural in the center. You really didn't show the the 3 wire configuration known as "Delta", there is no Netural in a Delta (triangle) configuration. Both configurations transfer power equally, but for long distances the Delta is used to save the need for a forth cable (cost savings in that case). Transformers are used to convert Delta to Y so that different phases and voltages can be used. The Delta can only power 3 Phase equipment (which only factories have), but Y can power (in the US) 3 phase 208V, split phase 240V, and single phase 120V all from a single Y secondary. The Netural is normally tied to ground at the Transformer and again at the home as it enters the breaker panel.

Sharing what I know/learned:
- The long distance transmission lines for a power distribution systems are 3-phase "3-wire" systems. These power grid designs are for efficient power distribution and at the same time, save cost.
- There can be additional thinner lines situated at the highest points on the tower.  They are mainly for lightning protection.  These wires are too thin for neutral (N) line as return path.
- The steel tower structure itself is grounded locally for Protective Earth (PE), but it is NOT for alternative path for Neutral.  The earth (soil, rock, etc.) is never intended for Neutral "N" return path nor for 3-phase power imbalance.
- 3-wire transmission line with no real physical Neutral wire in existence, I would call it a Delta system.
My 2 cents.

Why is the transmission line balanced ? If a phase has a different load on the distribution network it should reflect a different load on the respective transmission phase, causing an imbalance. I believe it does cause different voltages in different phases if no neutral is there. I think it is called a neutral shift and can cause problems. However, power can be distributed such that an unequal load is unlikely. For example a large industrial power consumer will have a balanced 3 phase load on the distribution network. Consumer homes likely present a small load. However, if all the people in homes on the R phase decide to use the washing machine at the same time, a neutral shift will happen and might cause problems.

Fantastic explanation❤

There’s always neutral. Count the number of lines. They’re usually 2, 4, 7 excepting for house where’s there’s 3 in split phase. Neutral is the line that equalizes ground potential everywhere, being grounded at pretty much each fork. When it doesn’t exist, must be build at either substation or pole transformer, but what do you do if a hot line floats towards ground potential? Without neutral there’s always a possibility.

The three-phase star transformer is just 3 independent single phase transformers. The red primary only cares the currents on the red secondary.  Let's take the extreme case where only the secondary of the red phase of the right hand transformer has a load and the other two secondaries have no loads (no current).  Then the currents in the three right hand side primaries are certainly not balanced.  Stating that the circuit you have drawn is 'independent' just means that it is floating, ie: the absolute voltages with respect to ground could be anything.  It doesn't mean that it is balanced, and no actual explanation is given for that assertions.  I am guessing that the star points at each end are grounded in actual transmission lines.  I must be missing something here.  Please enlighten me.

Perfect explanation! 🎉 he emphasized the need for a balanced circuit to not have a neutral line.

I was confused at first then the light bulb lit up when you explained the houses being unbalanced. Thanks!

When the first telegraph lines were installed (about 1840, between Washington and Baltimore, I believe) they used a neutral wire to complete the circuit. Then they discovered that the circuit could be completed through a ground connection. This enabled them to use the return wire for additional communication.

I have seen lots of distribution lines that are delta connected with, of course, no neutral. Some power companies use them a lot, and they used to be more common years ago. So I would not say that a neutral must be used, but rather that a neutral is desirable for distribution lines. I’m not an electrical engineer, but I imagine that a distribution line with no neutral would need to be derated to a lower power carrying capacity than a similar line with a neutral, and also that more attention must be given to load balancing when designing the distribution network.

I wish someone would have explained this to us the simple way like you did, Gauravji....
Renewed understanding key concepts:
1. Transmission n/w
2. Distribution n/w
3. Balanced/ Unbalanced load
4. Netral wire concept

thanks for adding and recall our knowledge having said , HV system doenst need neutral cause there is no load to connect but at distribution side there are single phase circuit which needs neutral for circuit completion , that why we need, but at distribution side we also care to balance the load. and not let maximum amount of current to flow at neutral side.

If you have 3 phase power supply in your house, which is common in Europe and other places I believe, you can plug some devices that don't use the neutral wire at all. And they will work perfectly fine. One of them is a 3 phase motor. If you wire the windings in a delta pattern, you just hook up 3 phase wires to it and the neutral is completely not needed.

My schooling taught:
(for long distance transmission) =supply end as Star to provide centre-tap for earth purposes only;
the downstream transformer as a delta winding as there’s no supply neutral anyway

THank you for the excellent explanation.

We can also calculate the value of the voltage with this equation  v(t)=Vmax​sin(ωt+θ), knowing that phase two is shifted by 120 degrees relative to phase one, and the third phase is shifted by 240 degrees relative to the first; the sum gives zero."

Very nicely explained,  thank you