😮😮 The correct explanation is, In 3 phase delta (or star without neutral) circuits, no need of neutral as return path. Because, the return path for the each Line current will be provided by reaming two other lines 😮
Exactly And in residential connection neutral is required as almost all of our domestic appliances require 240V to run that is the phase voltage or the voltage between neutral and phase.
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.
Here in western Canada, it is common to see three phase and single phase distribution lines in rural areas with no neutral wire; the earth is used exclusively as the neutral conductor. The single phase lines of this type are referred to as SWER - single wire earth return.
On single phase distribution, two wires are used. The top wire is usually the neutral and is grounded. If you trace it back, it goes back to one of the 3 phases and the neutral. The grounded neutral provides some lighting protection and when things like tree branches fall and break the lines, the grounded neutral will drop and contact the live phase wire tripping protection devices like fuses or upstream breakers. Thar tends to keep live wires from hitting the ground posing danger.
Transmission lines typically carry high-voltage electricity over long distances. Since transmission lines primarily transmit power from generating stations to substations, they operate at very high voltages, often ranging from hundreds of thousands to millions of volts. In such high-voltage systems, the primary concern is to minimize energy loss and maximize efficiency. Neutral wires are not typically required for this purpose, as transmission lines are designed to carry balanced three-phase AC power. Additionally, the high voltage levels mean that any return currents can flow through the ground or other conductive paths, eliminating the need for a dedicated neutral wire. Therefore, transmission lines usually consist only of three phase conductors without a separate neutral conductor.
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.
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.
There isn't a neutral on the high voltage side for most single phase residential distribution in the U.S. The neutral that comes into the house is actually a center tap of the secondary side of the transformer winding. This gives us two opposite phases of 120V from each side of the secondary winding to the center tap, which is neutral. Across the entire secondary winding we get 120V + 120V = 240V, which we use to power higher power loads like stoves, clothes dryers, A/C compressor motors, etc. So the neutral in the house is just a construct of the center tapped secondary and is referenced to ground.
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
in the Primary distribution (high voltage network that leaves the substations for the distribution transformers) there is also no neutral, there are only the 3 phase cables at the top of the pole, because in the high and medium voltage, energy is a circuit isolated by transformers, requiring neutral only in low voltage (or secondary distribution)
Nutral is not just for balancing the loads. Its important for return current to the source. To complete circuit. Thats why nutral is grounded at the transformer side. To provide easy path for current with lowest resistance to back to the source. At Distribution side of course.
The neutral doesn’t “ balance the loads” … if the loads are equally loaded you do not require a neutral at all. In a balanced system minus & plus values are equal so the neutral conductor will equal zero at all times. The neutral carries the remainder of the current in an unbalanced load. As per kerchov law that states what goes in must equal what comes out. The path of least resistance is the neutral, the general mass of the earth has a variable resistance & the neutral is a constant connection of a set resistance they don’t even compare in resistivity. So if you are waiting for the star point to earth to become the “ path of least resistance” then you have a very long wait before its value beats the neutral. SMH.😂
@@goaway9487 You cant balance the load. How wil you do that ? This only works ive you for sure the users only use balanced machines, like motors. But that never will be the case, only in end users line. The earth is the nul line, he explained it wrong
Search for Delta Wye Substation. The solution is in the substation transformers. They can do a bit of balancing. But engineers have to balance single phase going to subdivisions periodically to ensure the load is mostly balanced across the three phases.
When there is no neutral then the currents are balanced by definition. They have to add to zero by Kirchhoff's laws but if the load impedances are not balanced then this only happens by the voltages across the three phases adjusting themselves. So if the loads are not well balanced then the three phase voltages will not be the same. In order to limit the imbalance in phase voltage and keep them in spec. the loads on each phase have to be distributed roughly equally between the properties. There are occasionally faults where the neutral connection to a local area goes open circuit and the result is out of spec and often damaging over-voltages appearing in peoples homes.
This happened to our neighborhood during the previous large geomagnetic storm. I have a server farm and have a lot of monitoring systems and our voltage went up to 300 volts on one phase and caused some damage throughout the neighborhood. It tripped over half our breakers but the main breaker did not trip since the over voltage only existed temporarily. That day was insane (weekend).
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.
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.
Interesting that you explain how the currents sum to zero by using a voltage vs. time diagram for the 3 phases. For clarity, you should have used a Current vs. time diagram instead.
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.
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.
We can also calculate the value of the voltage with this equation v(t)=Vmaxsin(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."
Great video! Just one question. The secondary part of the distribution transformer is feeding an imbalanced load, therefore it needs the neutral to carry the imbalance. We also know that the load on the secondary of a transformer directly impacts the load on the primary due to the interactions of the magnetic fluxes. If this is the case, how come that we dont see an imbalance on the primary side aswell?
You do see an imbalance, except it doesn't only load one phase like the star secondary. The imbalance will appear as greater load across two phases on the delta primary. This is the same as if you were to disconnect the neutral line's tie from the starpoint of the transformer. All the single phase loads will draw from one phase, go onto the broken neutral, travel through another load and back to another phase. (Of course you're now dividing line voltage unequally across differently sized single phase loads, but the analogue stands)
The return path is the other phases. Just as a 240v appliance doesn't need a neutral in the USA. When one phase is positive, the other is negative. In three phase, the same happens but distributed across the three. He really didn't explain it correctly in reference to neutral. In split phase (USA) you need the neutral to return power used in an imbalanced manner across the two phases (which are 120v potential) one uses a light bulb and another phase uses a dishwasher for instance. If you neutral goes open, the imbalance can return 240v into a 120v appliance. Moreover, in Europe, single phase is different. You have a hot that is 240v with a neutral that is zero.
I'm used to looking up and recognizing the wye configuration for secondary output of residential transformers. One day I looked up and I think I recognized a delta output from a pole transformer going to an auto shop. How do they manage to get a neutral wire to serve the shop from a delta configuration? Was I mistaken?
At 4:30, it looks like a circular argument. You're saying that the currents are balanced, BECAUSE the currents are balanced. The voltage waveforms are depicted, but does that mean the current waveforms are also balanced? But what if they are not balanced? Is that possible? Can an unbalanced load on the secondary of the downstream transformer cause an unbalance in the transmission line? I'm kind of thinking that BECAUSE there is no neutral, the currents are naturally balanced. Any "excess" or "shortage" of current in any phase is carried by the other 2 phases. In other words, the transmission line is self-balancing because, as you said at the start, the transmission lines are electrically isolated from the source and loads, and that's OK.
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.
Very good question! Actually, mid points of stars on both sides can be grounded, and earth can play the role of neutral wire. But this is not usually done for the purposes of protection. Having grounded mid points and neutral wire is the best option
I would add ... in the high voltage lines ( 420 KV ), the currents are not so hight ( Power = Voltage x Current ), and any difference ( or algebric sum ) among them is far more little ...
explanation provided here is wrong load imbalance on secondary side will indeed effect the primary... the exact reason why we don't see neutral on High voltage transmission is because those set of wires are Delta comnected.
@@MultiSigen Y∆ with generation in star and transmission in delta , it can be ∆∆ too with generation in delta and transmission also in delta transmission is generally in delta
I asked the same question. Logically, i think it does. From what i know, the power company uses the earth and also a wire on top of transmission lines poles tower as a return path to the main generator to even charges. The wire on top of pole towers is grounded, and his main purpose is to protect the power lines from getting hit by lightning. And also, if an airplane or helicopter happens to fall on the wires, it will hit this wire first.
@@martf1061The earth wire on top of Extra High Voltage line is only grounded . It does not provide any return paths. Yes the phases stay unbalanced in a line slightly but since the grid network is interconnected, it gets balanced.
There are no L-N loads at transmission voltage. L-N loads downstream of transformers fed by transmission becomes unbalanced 3 phase current, I2, in the transmission circuit. Utility generators have I2 limits, so the utilities try to keep their LN loads equally loaded on the phases to keep I2 back up at the generators from getting too large. Note, unbalance does not cause neutral current, I0.
The simple reason transmission lines are delta with no neutral is, If there is a fault to ground, the fault current returns through the earth and the grounded static line if provided to the source station where it is a grounded at the a source transformer via why out put configuration or a delta grounding transformer to sense the return current and to trip the source breaker. Simple.
Many of the comments express thanks for explaining why 3 phase transmission does not require a neutral wire . ( see 2:07/8:45 ) But I wonder if these people understand that in the 920 Kv TRANSFORMER : the current of RED phase flows to the PRI ; that current is returned from the PRI back to the YELLOW and Blue windings of the 920 kv transformer YELLOW Red Blue BLUE Red Yellow
Surely such transmission lines are Delta connected, only to be transformed to Star at the local sub-station, thereby not using a neutral and saving cable cost !
Who connect secondary with primary through neutral. It's only we connect secondary coil in star winding pattern and from all RYB connected point, we take neutral conductor.
Surely you still need to load each phase as evenly as possible, else you're going to have wildly different currents in each phase. Yes, it's balanced, but the maximum capacity can't be achieved unless the currents in the three phases are equal.
at around 5:11 you state from the graph that the current shown is zero when in fact this graph is showing voltage not current. So the voltage is zero at 360 and if no voltage, then there is no current. Semantics but the graph is VOLTAGE over time, nothing shown indicates what the current is.
I thought that for long distance transmission, the delta configuration would be used, and then at the substation after stepping down the voltage, it would be converted to a star configuration for distribution.
I think of a caveat. If the distribution transformer is composed of 3 separate single phase transformers, as sometimes is done, then the transmission line would have to incorporate a neutral conductor or at least utilize ground path to transfer unbalanced power. Otherwise voltage on the unbalanced load will collapse
But why is a circuit that is unbalanced on the secondary side (distribution line), balanced on the primary side (transmission line)? I understand that they are independent of each other, but how?
In 11KV , I have seen no neutral, but before substation why there are 6 wires? And at distribution (step down) transformer, how the neutral line is introduced, please explain the connections
But how do you connect balanced transmission line to unbalanced distribution line? Where do you connect N in the unbalanced distribution line? To the ground? Then we still have 4 lines in the transmission line: 3 wires and ground that carries N.
We have a 110 kV railway power line here. One circuit has two conductors! There are two circuits on the mast, so four conductors. At the other end is a transformer with one primary and one secondary winding. No three-phase network. The railway then runs to ground at 15kV 16⅔ Hz
Thank you for sharing such valuable information sir! Would it also be possible for you to share your knowledge about Open Delta (V-V) and Open Wye - Open Delta Connections? Hoping for you to notice my comment and make a video about the topic I mentioned. 😁
Ohh my god the way you explained.... Thank you so much
Happy to help
Fantastic Explanation.
Yes. That’s right in case of distribution network. In the video i am specifically talking about the transmission network..
😮😮
The correct explanation is, In 3 phase delta (or star without neutral) circuits, no need of neutral as return path. Because, the return path for the each Line current will be provided by reaming two other lines 😮
Exactly
And in residential connection neutral is required as almost all of our domestic appliances require 240V to run that is the phase voltage or the voltage between neutral and phase.
And also in Distribution side he was not provide Graph and explain it unbalance current phenomenon
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.
Here in western Canada, it is common to see three phase and single phase distribution lines in rural areas with no neutral wire; the earth is used exclusively as the neutral conductor. The single phase lines of this type are referred to as SWER - single wire earth return.
Plenty of SWER in South Africa and Namibia. South African development in th 90s. Pleased to hear they are using it in Canada.
And in AU
Same in Brazil. Very common, specially in remote areas, where power demand is low. Otherwise, 3 phase distribution system is the norm.
On single phase distribution, two wires are used. The top wire is usually the neutral and is grounded. If you trace it back, it goes back to one of the 3 phases and the neutral. The grounded neutral provides some lighting protection and when things like tree branches fall and break the lines, the grounded neutral will drop and contact the live phase wire tripping protection devices like fuses or upstream breakers. Thar tends to keep live wires from hitting the ground posing danger.
Transmission lines typically carry high-voltage electricity over long distances. Since transmission lines primarily transmit power from generating stations to substations, they operate at very high voltages, often ranging from hundreds of thousands to millions of volts.
In such high-voltage systems, the primary concern is to minimize energy loss and maximize efficiency. Neutral wires are not typically required for this purpose, as transmission lines are designed to carry balanced three-phase AC power. Additionally, the high voltage levels mean that any return currents can flow through the ground or other conductive paths, eliminating the need for a dedicated neutral wire. Therefore, transmission lines usually consist only of three phase conductors without a separate neutral conductor.
Ibn taymia discovered that?
Technically, there is no energy loss but there can be an electrical power loss.
@@georgejetson4378 Considering power is simply energy/time, that's a bit hard to support.
@@stargazer7644 Energy unlike power is conservative.
Perfect
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.
Sort of, but telegraph lines were not 3 phase. They were DC. In that, the so called "neutral" was just a return and not a true neutral.
He is right and he has also given the main reason why there is no neutral wire congratulations 🎉🎉
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.
THank you for the excellent explanation.
There isn't a neutral on the high voltage side for most single phase residential distribution in the U.S. The neutral that comes into the house is actually a center tap of the secondary side of the transformer winding. This gives us two opposite phases of 120V from each side of the secondary winding to the center tap, which is neutral. Across the entire secondary winding we get 120V + 120V = 240V, which we use to power higher power loads like stoves, clothes dryers, A/C compressor motors, etc. So the neutral in the house is just a construct of the center tapped secondary and is referenced to ground.
Exactly. But since its a single phase transformer ( using only one phase at the primary ) , it automaticaly unbalances the high voltage lines.
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
Looks like your drawing of P and S above the R line at the 2.12 min mark were incorrect. Primary is on the left not the right side and vices Versa.
I was confused at first then the light bulb lit up when you explained the houses being unbalanced. Thanks!
in the Primary distribution (high voltage network that leaves the substations for the distribution transformers) there is also no neutral, there are only the 3 phase cables at the top of the pole, because in the high and medium voltage, energy is a circuit isolated by transformers, requiring neutral only in low voltage (or secondary distribution)
Nutral is not just for balancing the loads. Its important for return current to the source. To complete circuit. Thats why nutral is grounded at the transformer side. To provide easy path for current with lowest resistance to back to the source. At Distribution side of course.
thank you brother
Very nice
The neutral doesn’t “ balance the loads” … if the loads are equally loaded you do not require a neutral at all. In a balanced system minus & plus values are equal so the neutral conductor will equal zero at all times.
The neutral carries the remainder of the current in an unbalanced load. As per kerchov law that states what goes in must equal what comes out.
The path of least resistance is the neutral, the general mass of the earth has a variable resistance & the neutral is a constant connection of a set resistance they don’t even compare in resistivity. So if you are waiting for the star point to earth to become the “ path of least resistance” then you have a very long wait before its value beats the neutral. SMH.😂
@@goaway9487 You cant balance the load. How wil you do that ? This only works ive you for sure the users only use balanced machines, like motors. But that never will be the case, only in end users line. The earth is the nul line, he explained it wrong
Search for Delta Wye Substation. The solution is in the substation transformers. They can do a bit of balancing.
But engineers have to balance single phase going to subdivisions periodically to ensure the load is mostly balanced across the three phases.
The reason is that the distribution system always feeds into a balanced load, ie, transformer windings.
Your explanation Sir was EXCELLENT. Thank You !
Glad it was helpful!
When there is no neutral then the currents are balanced by definition. They have to add to zero by Kirchhoff's laws but if the load impedances are not balanced then this only happens by the voltages across the three phases adjusting themselves. So if the loads are not well balanced then the three phase voltages will not be the same. In order to limit the imbalance in phase voltage and keep them in spec. the loads on each phase have to be distributed roughly equally between the properties. There are occasionally faults where the neutral connection to a local area goes open circuit and the result is out of spec and often damaging over-voltages appearing in peoples homes.
This happened to our neighborhood during the previous large geomagnetic storm. I have a server farm and have a lot of monitoring systems and our voltage went up to 300 volts on one phase and caused some damage throughout the neighborhood. It tripped over half our breakers but the main breaker did not trip since the over voltage only existed temporarily.
That day was insane (weekend).
Great job explaining this…..
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.
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.
Great video, very good, thank you Sir! 😊
Thank you for educating me!
Interesting that you explain how the currents sum to zero by using a voltage vs. time diagram for the 3 phases. For clarity, you should have used a Current vs. time diagram instead.
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.
Very well explained.
Thank you very much.
Glad it was helpful!
Found this explanation useful as I'm preparing to enrol for PhD or Ms in Electrical Engineering
all the best!!
Good, informative video!
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.
The exact topic i was thinking of today!! 🤯
We can also calculate the value of the voltage with this equation v(t)=Vmaxsin(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."
Great video! Just one question. The secondary part of the distribution transformer is feeding an imbalanced load, therefore it needs the neutral to carry the imbalance. We also know that the load on the secondary of a transformer directly impacts the load on the primary due to the interactions of the magnetic fluxes. If this is the case, how come that we dont see an imbalance on the primary side aswell?
He explained it wrong. How can you balance the load? They cant. Only the end user, like a motor or heater with the same resistance on each fase.
Search for Delta Wye Substation. The solution is in the substation transformers. They are not just 3 separate transformers.
You do see an imbalance, except it doesn't only load one phase like the star secondary. The imbalance will appear as greater load across two phases on the delta primary. This is the same as if you were to disconnect the neutral line's tie from the starpoint of the transformer. All the single phase loads will draw from one phase, go onto the broken neutral, travel through another load and back to another phase.
(Of course you're now dividing line voltage unequally across differently sized single phase loads, but the analogue stands)
The return path is the other phases. Just as a 240v appliance doesn't need a neutral in the USA. When one phase is positive, the other is negative. In three phase, the same happens but distributed across the three. He really didn't explain it correctly in reference to neutral.
In split phase (USA) you need the neutral to return power used in an imbalanced manner across the two phases (which are 120v potential) one uses a light bulb and another phase uses a dishwasher for instance. If you neutral goes open, the imbalance can return 240v into a 120v appliance.
Moreover, in Europe, single phase is different. You have a hot that is 240v with a neutral that is zero.
Thank you so much...very informative,
Glad it was helpful!
Excellent work.pls make video on surge impedence loading of transmission lines
Good explained
Glad it helped
many thanks plz need to explain how as example in 11 kv lines with no potential difference and how different in the phoser works
I'm used to looking up and recognizing the wye configuration for secondary output of residential transformers. One day I looked up and I think I recognized a delta output from a pole transformer going to an auto shop. How do they manage to get a neutral wire to serve the shop from a delta configuration? Was I mistaken?
Thank you so much for the explanation :)
Can 5:14 be used to conclude that neutral in the socket "is neutral" because it is connected to all 3 phases?
At 4:30, it looks like a circular argument. You're saying that the currents are balanced, BECAUSE the currents are balanced. The voltage waveforms are depicted, but does that mean the current waveforms are also balanced? But what if they are not balanced? Is that possible? Can an unbalanced load on the secondary of the downstream transformer cause an unbalance in the transmission line? I'm kind of thinking that BECAUSE there is no neutral, the currents are naturally balanced. Any "excess" or "shortage" of current in any phase is carried by the other 2 phases. In other words, the transmission line is self-balancing because, as you said at the start, the transmission lines are electrically isolated from the source and loads, and that's OK.
Transformers are in star. Phase to phase 440v. Phase to star point 240volt.
well and simply explained !!! thank you
Glad it was helpful!
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.
Thanks very much.
In addition, faults also register as phase imbalances, so in addition to ground return faults the protective devises also watch phase imbalance.
if secondary is unbalanced how can primary be balanced
Hi Sir, your videos are very helpful and informative, please also make a video about neutral ground resistors. Thank you sir
Thanks
Curious as to why you did not mention the neutral and Earth connection at the center point of the transformer on the distribution side.
Isn't integral to the explanation he is giving. Yes you would have your N to Ground connections to prevent floating voltages
Very good question!
Actually, mid points of stars on both sides can be grounded, and earth can play the role of neutral wire. But this is not usually done for the purposes of protection. Having grounded mid points and neutral wire is the best option
I would add ... in the high voltage lines ( 420 KV ), the currents are not so hight ( Power = Voltage x Current ), and any difference ( or algebric sum ) among them is far more little ...
explanation provided here is wrong load imbalance on secondary side will indeed effect the primary...
the exact reason why we don't see neutral on High voltage transmission is because those set of wires are Delta comnected.
Which configuration? ΥΔ, ΔΔ or ΔΥ?
@@MultiSigen Y∆ with generation in star and transmission in delta , it can be ∆∆ too with generation in delta and transmission also in delta
transmission is generally in delta
Exactly my thought .. so now am behind with the explanation above...🤔
Well, the whole reason we can use delta connections is because the load is balanced!
Is the imbalance current flows through earth via neutral ? or only the earth fault current flows through the earth.? please explain.
Thats how we know how far out from the source station the issue is. Phase A to ground. 8 miles. Or phase AB. 6 miles. Trees normally.
Thank you Sir
Most welcome
If the distribution network is unbalanced, wouldn't the uneven loads between phases cause an imbalance in the transmission network?
I asked the same question.
Logically, i think it does.
From what i know, the power company uses the earth and also a wire on top of transmission lines poles tower as a return path to the main generator to even charges.
The wire on top of pole towers is grounded, and his main purpose is to protect the power lines from getting hit by lightning. And also, if an airplane or helicopter happens to fall on the wires, it will hit this wire first.
@@martf1061The earth wire on top of Extra High Voltage line is only grounded . It does not provide any return paths. Yes the phases stay unbalanced in a line slightly but since the grid network is interconnected, it gets balanced.
There are no L-N loads at transmission voltage. L-N loads downstream of transformers fed by transmission becomes unbalanced 3 phase current, I2, in the transmission circuit. Utility generators have I2 limits, so the utilities try to keep their LN loads equally loaded on the phases to keep I2 back up at the generators from getting too large. Note, unbalance does not cause neutral current, I0.
6:40 Neutral is needed in distribution system because it is not balanced=we can not control the load
Which size of cable using in Transmission line?
Sizes are mentioned as rabbit, wolf, panther , zebra, moose etc as per size
Good
The simple reason transmission lines are delta with no neutral is, If there is a fault to ground, the fault current returns through the earth and the grounded static line if provided to the source station where it is a grounded at the a source transformer via why out put configuration or a delta grounding transformer to sense the return current and to trip the source breaker. Simple.
There is a neutral in Wye secondary generated electrical systems. Allot of generated electricity is Delta - Wye.
Many of the comments express thanks for explaining why 3 phase transmission does not require a neutral wire . ( see 2:07/8:45 ) But I wonder if these people understand that in the
920 Kv TRANSFORMER : the current of RED phase flows to the PRI ; that current is returned from the PRI back to the YELLOW and Blue windings of the 920 kv transformer
YELLOW Red Blue
BLUE Red Yellow
Thanks, you answered the exact question I had in mind!
Electrical infrastructure is becoming critical for civilization, obviously. When everybody has a clear understanding we can make good decisions.
Hi Gaurav, your videos are great. Please do a video about Transformers vectors group and why we need them.
Thank you. Sure. Will try
Surely such transmission lines are Delta connected, only to be transformed to Star
at the local sub-station, thereby not using a neutral and saving cable cost !
Transmission 115 kv and above Y
Thank you, GJ.
The structure metal is grounded as underground lines..., I suppose, there U have your neutral. It will make a fase neutral short circuit.
Who connect secondary with primary through neutral. It's only we connect secondary coil in star winding pattern and from all RYB connected point, we take neutral conductor.
Please be aware that in the UK phase colours changed to Brown, Grey and Black with the neutral now blue many years ago.
Superb explanation, thank you sir 👍
You're most welcome
Thanks my teecher
sir in sending and recieving end in transmission t/f neutral grounding is done or necessary?
So we can use star connection without neutral?
The diagram does not show max or min unless slight lag between voltage and current?
what about DELTA connected Transmission Lines?
Surely you still need to load each phase as evenly as possible, else you're going to have wildly different currents in each phase. Yes, it's balanced, but the maximum capacity can't be achieved unless the currents in the three phases are equal.
at around 5:11 you state from the graph that the current shown is zero when in fact this graph is showing voltage not current. So the voltage is zero at 360 and if no voltage, then there is no current. Semantics but the graph is VOLTAGE over time, nothing shown indicates what the current is.
Helpful
Sir why did you took
R phase =0
Y phase =-Imax
B phase = Imax
Please teach this
Very interesting explanation
I thought that for long distance transmission, the delta configuration would be used, and then at the substation after stepping down the voltage, it would be converted to a star configuration for distribution.
My thought too...🤔
How can the transmission lines be perfectly balanced, if there is unbalanced loads ?
Awesome video! does that also go for sub-transmission lines (66kV)?
I think of a caveat. If the distribution transformer is composed of 3 separate single phase transformers, as sometimes is done, then the transmission line would have to incorporate a neutral conductor or at least utilize ground path to transfer unbalanced power. Otherwise voltage on the unbalanced load will collapse
But why is a circuit that is unbalanced on the secondary side (distribution line), balanced on the primary side (transmission line)? I understand that they are independent of each other, but how?
How about PE / Earth conductors, why is it not needed in transmission?
thanks very good explained with quality.
Glad it was helpful!
Thank you for the explanation
Glad it was helpful!
Thanks. Good information for a learner of electricity
Thanks for watching
In 11KV , I have seen no neutral, but before substation why there are 6 wires?
And at distribution (step down) transformer, how the neutral line is introduced, please explain the connections
Neutral line comes from the star point of the transformer which is grounded at the transformer.
Nice ,,well done sir
Thank you 😊
Enlighted by your analysis of this.Thanks.
But how do you connect balanced transmission line to unbalanced distribution line? Where do you connect N in the unbalanced distribution line? To the ground? Then we still have 4 lines in the transmission line: 3 wires and ground that carries N.
You do not connect them. You use transformers.
Please sir can you work a video on " difference between grounding and earthing ".....i got confused on it !
there is no difference , you asking like what is the difference between india and bharat or hindostan,
We have a 110 kV railway power line here. One circuit has two conductors!
There are two circuits on the mast, so four conductors.
At the other end is a transformer with one primary and one secondary winding. No three-phase network.
The railway then runs to ground at 15kV 16⅔ Hz
High voltage transmission lines do not use Y scheme. They use exclusively delta configuration, thus system is balanced, and neutral does not exist.
Thank you for sharing such valuable information sir! Would it also be possible for you to share your knowledge about Open Delta (V-V) and Open Wye - Open Delta Connections? Hoping for you to notice my comment and make a video about the topic I mentioned. 😁
The transmission line is three phase so there is no neutral wire.
Thanks for making this video!
Glad it was helpful!