How 3 Phase Transformers Work why we need them
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Date: 2024-06-12
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Comments and reviews: 20
kls2020
Typically a step- up WYE Delta transformer is used between a generator and transmission line connected with the Generator connected to the Delta windings and the Transmission system connected to the WYE windings of the transformer. This provides isolation so a Line to Ground fault on the Transmission line cannot make its way back to the Generator as it see's it's source as the Transformer not the Generator. There will be a 30 degree electrical displacement ( or shift)between a WYE / Delta transformer primary /secondary winding voltages .
Another fun fact with a 3 Phase Delta transformer is if you lose power to one input phase it can still produce 3 phase voltages at a reduced capacity of 40%. From what I read years ago was that this is why they used this configuration for critical facilities such as Hospitals for more reliability.
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Typically a step- up WYE Delta transformer is used between a generator and transmission line connected with the Generator connected to the Delta windings and the Transmission system connected to the WYE windings of the transformer. This provides isolation so a Line to Ground fault on the Transmission line cannot make its way back to the Generator as it see's it's source as the Transformer not the Generator. There will be a 30 degree electrical displacement ( or shift)between a WYE / Delta transformer primary /secondary winding voltages .
Another fun fact with a 3 Phase Delta transformer is if you lose power to one input phase it can still produce 3 phase voltages at a reduced capacity of 40%. From what I read years ago was that this is why they used this configuration for critical facilities such as Hospitals for more reliability.
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engineering_mindset
One thing I never understood about 3-phase conditioning/generation. was the point of it. I get that it's more efficient at the point of consumption. but it's less efficient to generate. It's kind of like hybrid cars. because the electric motors are more efficient at the point of consumption, and gasoline carries energy more efficiently than batteries, we build them for the net efficiency. but (as always) it doesn't tell the whole story. The net efficiency is better. but the complexity, cost to manufacture, increased requirement for rare earths, and generally less dependability, means you don't really gain anything.
I see 3 phase as the same. Sure, it works. but to what end The only major benefit I see to 3-phase current, is reducing infrastructure requirements.
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One thing I never understood about 3-phase conditioning/generation. was the point of it. I get that it's more efficient at the point of consumption. but it's less efficient to generate. It's kind of like hybrid cars. because the electric motors are more efficient at the point of consumption, and gasoline carries energy more efficiently than batteries, we build them for the net efficiency. but (as always) it doesn't tell the whole story. The net efficiency is better. but the complexity, cost to manufacture, increased requirement for rare earths, and generally less dependability, means you don't really gain anything.
I see 3 phase as the same. Sure, it works. but to what end The only major benefit I see to 3-phase current, is reducing infrastructure requirements.
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power-max
3: 34 Actually(insert ackyhually meme here) when you have 3 phases, powering a balanced 3 phase load, you get truely constant power! not just almost constant. Power deliver is as smooth as DC! you can work this out in the math, just square the voltages to get the power and add the 3 together and the way the trig works out you get a constant value in the math, translating to a horizontal line of power transfer, or smooth power transfer with no ripple at all!
This does not apply for complex or nonlinear loads of course, or where you lose a phase or where the power draw across the three phases isn't the same. It should ) apply in any case where the load is resistive, inductive (lagging current, or capacitive (leading) and balanced.
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3: 34 Actually(insert ackyhually meme here) when you have 3 phases, powering a balanced 3 phase load, you get truely constant power! not just almost constant. Power deliver is as smooth as DC! you can work this out in the math, just square the voltages to get the power and add the 3 together and the way the trig works out you get a constant value in the math, translating to a horizontal line of power transfer, or smooth power transfer with no ripple at all!
This does not apply for complex or nonlinear loads of course, or where you lose a phase or where the power draw across the three phases isn't the same. It should ) apply in any case where the load is resistive, inductive (lagging current, or capacitive (leading) and balanced.
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VTdarkangel
Some interesting things about 3phase transformer connections.
Delta - Y is usually preferred. Thats because 3rd harmonics don't get transmitted back into the incoming line.
A zig-zag transformer can be used to create a central ground for delta connections, but that is only used for special industrial settings, at least to the best of my knowledge.
In the US, Delta high leg and open delta are becoming obsolete. They were an out growth of the split phase systems used in residential power configurations. They are usually not installed in new service systems anymore. The vast majority of operating ones are legacy connections.
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Some interesting things about 3phase transformer connections.
Delta - Y is usually preferred. Thats because 3rd harmonics don't get transmitted back into the incoming line.
A zig-zag transformer can be used to create a central ground for delta connections, but that is only used for special industrial settings, at least to the best of my knowledge.
In the US, Delta high leg and open delta are becoming obsolete. They were an out growth of the split phase systems used in residential power configurations. They are usually not installed in new service systems anymore. The vast majority of operating ones are legacy connections.
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19Dev98
Really good video, well put together as always and started really strong. Feel like it fell away at the end though and spent way too much time doing calculations at the end. Would’ve been much more interesting/relevant/beneficial to hear about some of the ancillary components to a transformer. Eg. their mechanical and electrical protection systems (buchholz, WTIs, duo bias. Earthing transformers, LERs/NERs. For all the talk on winding configurations, no mention of a Z winding which is much more common than an open Delta at least in my experience.
Would love to see a part 2 to this video
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Really good video, well put together as always and started really strong. Feel like it fell away at the end though and spent way too much time doing calculations at the end. Would’ve been much more interesting/relevant/beneficial to hear about some of the ancillary components to a transformer. Eg. their mechanical and electrical protection systems (buchholz, WTIs, duo bias. Earthing transformers, LERs/NERs. For all the talk on winding configurations, no mention of a Z winding which is much more common than an open Delta at least in my experience.
Would love to see a part 2 to this video
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engineering_mindset
One question. In high leg if neutral (we call it zero) is connected to the middle of coil why is that wire (line) not part of circuit with flow of electricity Is it because ground is connected at the same point as Neutral (so that makes it actually Neutral/zero) I did learn about high voltage electrical engineering in middle school but we did not have practice to see on actual example in the world how it looks when neutral is connected in high leg delta, i do not have a clue how is it called here, but i understand Delta and Star connections no problem.
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One question. In high leg if neutral (we call it zero) is connected to the middle of coil why is that wire (line) not part of circuit with flow of electricity Is it because ground is connected at the same point as Neutral (so that makes it actually Neutral/zero) I did learn about high voltage electrical engineering in middle school but we did not have practice to see on actual example in the world how it looks when neutral is connected in high leg delta, i do not have a clue how is it called here, but i understand Delta and Star connections no problem.
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atsimas
This video is why in Europe we mainly just have one type of transformer. Everyone except heavy industry etc use 220 -240 VAC so none of the delta or wye nonsense. Just imagine, not just the less maths but the fewer spare parts to carry to fix the damages. Also, because of standardization hopefully cheaper products. Higher voltage finally means a greater margin to serve. As for safety, even 12vdc can kill you under the right conditions. Notice the term right conditions and avoid it at any cost.
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This video is why in Europe we mainly just have one type of transformer. Everyone except heavy industry etc use 220 -240 VAC so none of the delta or wye nonsense. Just imagine, not just the less maths but the fewer spare parts to carry to fix the damages. Also, because of standardization hopefully cheaper products. Higher voltage finally means a greater margin to serve. As for safety, even 12vdc can kill you under the right conditions. Notice the term right conditions and avoid it at any cost.
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engineering_mindset
Question, the voltage induced in a coil is proportional to the derivative or change of the magnetic field, and the magnetic field is proportional to the current, and also the derivative of a sine wave is a cosine wave, which is just the sine wave 90 degrees ahead, meaning using this logic the secondary should be 90 degrees out of phase from the primary but it is not, why is that
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Question, the voltage induced in a coil is proportional to the derivative or change of the magnetic field, and the magnetic field is proportional to the current, and also the derivative of a sine wave is a cosine wave, which is just the sine wave 90 degrees ahead, meaning using this logic the secondary should be 90 degrees out of phase from the primary but it is not, why is that
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Hemshemsems
I do not go into splitfase as we have 230/400, all our grid is 3 fase from producer to home. Most of our grid except a small part of 10kv and 60kv (60-150-400kv are airborn usually) is plowed down in the ground, and it will create less blackouts in adverse weather. All these different voltages and conversions, 120-208-240-277-480, 230/400 50hz is all we need in 90% of cases.
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I do not go into splitfase as we have 230/400, all our grid is 3 fase from producer to home. Most of our grid except a small part of 10kv and 60kv (60-150-400kv are airborn usually) is plowed down in the ground, and it will create less blackouts in adverse weather. All these different voltages and conversions, 120-208-240-277-480, 230/400 50hz is all we need in 90% of cases.
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DamonJohnCollins
Any chance you could follow this up with pros and cons of each system and give examples of why they are selected
And has the selection been changing because of the reduced need for 277V lighting (moving to 120V LED)
And include thoughts for other upcoming changes (maybe to accommodate energy storage systems
Thanks, as always, for the excellent content!
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Any chance you could follow this up with pros and cons of each system and give examples of why they are selected
And has the selection been changing because of the reduced need for 277V lighting (moving to 120V LED)
And include thoughts for other upcoming changes (maybe to accommodate energy storage systems
Thanks, as always, for the excellent content!
reply
ericsorensen4691
I get why laminated plates are used to prevent eddy currents; would they be further reduced if the transformer core was made of laminated steel wire instead of plates Are plates used because they're cheaper than stacked laminated wire loops, or does it just not make a significant difference to have the core separated in that second dimension
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I get why laminated plates are used to prevent eddy currents; would they be further reduced if the transformer core was made of laminated steel wire instead of plates Are plates used because they're cheaper than stacked laminated wire loops, or does it just not make a significant difference to have the core separated in that second dimension
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jensschroder8214
0: 22 In Europe the output is always a Y configuration.
The voltage is 220 to 240 volts to ground. Or from phase to phase 380 to 420v.
Often referred to as 230/400V. 230 SQR(3)=400 V
Rarely there is 230V from phase to phase (and 127V from phase to ground.
The domestic sockets are connected to 220 to 240V 50Hz. Mostly 230V 50Hz
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0: 22 In Europe the output is always a Y configuration.
The voltage is 220 to 240 volts to ground. Or from phase to phase 380 to 420v.
Often referred to as 230/400V. 230 SQR(3)=400 V
Rarely there is 230V from phase to phase (and 127V from phase to ground.
The domestic sockets are connected to 220 to 240V 50Hz. Mostly 230V 50Hz
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kondzio2003
Great video. I'm European and our energy system is much simpler. Apartments in blocks are usually connected to 1 phase, and detached houses to 3 phases, and that's all. In Poland we have one low voltage system of 230/400V and one medium voltage system of 15kV (sometimes 30kV. And above that there are high voltages of 110kV, 220kV and 400kV.
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Great video. I'm European and our energy system is much simpler. Apartments in blocks are usually connected to 1 phase, and detached houses to 3 phases, and that's all. In Poland we have one low voltage system of 230/400V and one medium voltage system of 15kV (sometimes 30kV. And above that there are high voltages of 110kV, 220kV and 400kV.
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Hogaboga101
Great video, interesting to watch as a norwegian linesman. We do not have a single 1 phase transformer in our entire grid also I have never even heard of the High Leg Delta transformer.
I have always noticed single phase transformers in games and wondered wich backwater country this is supposed to be from, guess it was the US
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Great video, interesting to watch as a norwegian linesman. We do not have a single 1 phase transformer in our entire grid also I have never even heard of the High Leg Delta transformer.
I have always noticed single phase transformers in games and wondered wich backwater country this is supposed to be from, guess it was the US
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stratfanstl
Would not have recommended mentioning connecting an oscilloscope to 120v power in a US home. There are subtle but crucial implications about ground and neutral that will likely smoke most AC powered scopes. It is safe if you use a handheld internally powered scope but NOT a wall powered scope. Great explanation overall.
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Would not have recommended mentioning connecting an oscilloscope to 120v power in a US home. There are subtle but crucial implications about ground and neutral that will likely smoke most AC powered scopes. It is safe if you use a handheld internally powered scope but NOT a wall powered scope. Great explanation overall.
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engineering_mindset
Fantastic video, but to explain the ground in the y configuration you could also explain the cases of simmetric and balanced where current and voltage have the same module and phase shift of 120 degrees therefore in the central node the sum of the 3 currents is 0 so as to obtain the return of the neutral
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Fantastic video, but to explain the ground in the y configuration you could also explain the cases of simmetric and balanced where current and voltage have the same module and phase shift of 120 degrees therefore in the central node the sum of the 3 currents is 0 so as to obtain the return of the neutral
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No_Preservations
So what makes design engineers choose one transformer configuration over another Type of equipment and demand on client side is all i can think of Why would you want a delta vs a Y on secondary If voltages are the same Are there benefits/drawbacks to have Y as secondary for neutral safety
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So what makes design engineers choose one transformer configuration over another Type of equipment and demand on client side is all i can think of Why would you want a delta vs a Y on secondary If voltages are the same Are there benefits/drawbacks to have Y as secondary for neutral safety
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ralanham76
11: 11 I don't see how the thing would overload.
You wouldn't put more breakers loaded then you could get out. at some point all the circuits would be maxed which should be just under the Max of the transformer.
In the picture above you would put the three 23k loads on different legs.
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11: 11 I don't see how the thing would overload.
You wouldn't put more breakers loaded then you could get out. at some point all the circuits would be maxed which should be just under the Max of the transformer.
In the picture above you would put the three 23k loads on different legs.
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TheRealWindlePoons
Top explanations, thank-you.
I was not familiar with high leg delta, I have never come across it here in the UK. I was however aware of the 60hz USA vs 50Hz Europe. The centre tapped 120V domestic mains is a US thing too. In the UK we just get neutral and a 240V line.
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Top explanations, thank-you.
I was not familiar with high leg delta, I have never come across it here in the UK. I was however aware of the 60hz USA vs 50Hz Europe. The centre tapped 120V domestic mains is a US thing too. In the UK we just get neutral and a 240V line.
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finemechanic
When you talk about the power of a single phase system, the graphs show voltage, current and power, but for 2 and 3 phase system you switch to show just phase voltages and the rectified voltage, not power. In fact, for the balanced 3 phase system power is strictly constant.
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When you talk about the power of a single phase system, the graphs show voltage, current and power, but for 2 and 3 phase system you switch to show just phase voltages and the rectified voltage, not power. In fact, for the balanced 3 phase system power is strictly constant.
reply
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