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Three Phase: How to Calculate Neutral Current in an Imbalanced Load
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- เผยแพร่เมื่อ 19 พ.ย. 2019
- In this video we will carry out an experiment to measure neutral currents in an imbalanced three phase load. Then we will demonstrate one method of calculating the neutral current. Other methods will follow in future videos.
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Imbalanced load? More like "These videos are solid gold!" Thanks so much for taking the time to record, edit and post them.
Thanks Joe. You just explained 3 phase calculations to my son in a way I couldn’t do. You represent what the internet can be.
Really useful and clear Joe. I've always struggled with 3 phase for over 25 years and found imbalanced loads confusing - until now :) Many many thanks!
Thanks for the feedback Mark, comments like this make my day. The next video I'm doing on three phase gives a more visual understanding of what's going on, look out for it this week! 👍
Sir can you please explain how the neutral conductor stabilizes the phase voltage in an unbalanced load?
My god, spent days trying to learn this whilst in my training day and never really grasped it.
Just watched this video whilst having my dinner and its clear as day now, top work Joe👍🏻
Thanks Steven, glad it's helped to clarify things a bit. There'll be other simpler methods to come but this is my favourite for visualisation and accuracy.
You are the best trainer I have ever come across. Thank you Joe.
Мужик с Ютуба объясняет гораздо лучше чем многие преподаватели с учёными степенями...
Great tutorial for a purely resistive unbalanced load, its gets a bit more tricky with extra inductive or capacitive elements
An amazing explanation Joe 👍
Cheers Gaz!
What a great method of explaining unbalanced load calculations for students who may not have encountered complex number addition.
Thanks Rob, it's the way I like doing it as it combines accuracy and a visual representation. Stay tuned for more! 👍
We did this in college, came out completely baffled, the way you explain, it's a work of art. Thankyou.
Aw, thanks Andrew, that's really kind of you, hope the videos help. 👍
As somebody who works in the trades and only has a surface level understanding of engineering and the math heavy theory of AC systems - thank you so much! I wish I found this video six years ago!
I would have zero chance of understanding all these equations without your videos. Thank you 👍 Fascinating that so much comes back to trigonometry. Mind blowing actually!
It's awesome how so much is explained by triangles isn't it? So glad it's helping you out Charlotte. 😊
Wow what a video Joe 👍
A nifty explanation of a mathematical way of doing this, this only works for loads with the same power factor/phase shift that are 120Deg apart. for loads with dissimilar phase shifts it can only be done with the parallelogram method ( phasor diagrams) or by calculating polar co-ordinates.
Thanks for the Video.
I used a spreadsheet for this at my last company. So it has been a long time, like 20 years, since I had to calculate. Thanks so much for posting this so I could create a spreadsheet for this company, and forget the formulas again, lol. The triangles were helpful to remind me of the math. :)
Unbelievable what an amazing video Joe.... star struck 🤩
Thank you mate. And beautiful hand writing!
Excellent explanation sir, thank you very much.
Thanks Joe, done this all years ago didn't make much sense then. But with these steps and the practical process at starts makes it easy to follow. Keep up the good work👍
Cheers Sam, will do. 😊
NICE one. thanks for the sharing.. without complex number.
Wow, what a great video Joe. The method you show in this video is a great method for visualising what happens with the neutral current and it maybe a long winded method, but you can follow the steps through specially seeing how it could be very easy to make a negative number become positive.
I also write the formula out when transposing and someone showed that using a different coloured pen when going through the transposition can help you spot any mistakes.
Thanks Chris, I really appreciate the feedback, funnily enough I use different coloured pens when I'm teaching transposition on the board so I may have to bring that in to my vids. Other neutral calculation methods on the way!
Amazing Bru . Well done . I never enjoyed paying attention to so much geometry and trigonometry ever. I'm like almost in my 50s
Brilliant method,easy to understand the procedure.
Good to know! 😊
I think there's an easier way of doing the trig. It has a built in method of reminding you whether to use sin or cos, uses the entire phase angles and doesn't require adding, subtracting or potentially forgetting about 90 or wondering whether the resulting phasors are positive or negative. It's also easier to type in to your calculator!
Start with L1. Angle is 0 (we're working in degrees). 4.1*sin(0)=0 and 4.1*cos(0)=4.1. From this it clearly reminds you that sin of the total phase angle is the x component and cos is the y component.
We can then do L2: 16.1*sin(120)=13.94 and 16.1*cos120=-8.05
L3: 8.1*sin(240)=-7.01 and 8.1*cos(120)=-4.05
sqrt((L1sin0+L2sin120+L3sin240)^2+(L1cos0+L2cos120+L3sin240)^2) = 10.58
Thanks for the suggestion. 😊
Excellent video. Thank you so much!
you made my sunday morning osm thank you for sharing your knnowledge
Sir, Thank you very much for this video, you are the best teacher and I think engineering college teachers should learn from you that how to teach the students .
Ah, that's really kind, thanks very much.
Hi Joe I have one question for you....? Do you work with GSH Electrical? I watch a lot of his videos and I think I am falling in love with Gaz from GSH... I look forward to your answer. Keep up the amazing work on electrical science and principles you’re making a difference to the industry Joe 👍
very good explanation, thank you
Brilliant Joe. Perfectly explained in small understandable steps. Never quite got my head round vectors so this explanation is a true light bulb moment! I assume you could calculate the angle of the Neutral by establishing what angle has a tangent of 8 divided by 6.93? - 1.15 - 49 degrees? - looks about right.
That's so nice to hear, thanks so much for the feedback and you're spot on regarding the angle of the neutral current. Love it when people get a lightbulb moment!
This video really helps
Good to know. Thanks for watching and commenting! 😊
this was so satisfying i loved it, were so lucky to live in a time where we can learn this visually at the comfort of our homes! the teachers not bad either haha
superbly done! thank you.
Great video Joe, you do explain it really good but cant wait for the easier way to calculate 🤯.... 🤣👍🏻
Coming Wednesday, all being well!
Very good and easy to understand! Brilliant!
Thanks very much, I hope it helped. 😊
Very helpful, found this method easier than the one i've been shown
Excellent demonstration.
Slam dunk of a video. Thank you!
I was thinking about 3phases Ac generators with delta connections, you are teaching the first subject of high school trigonometry course.
Thank you anyway.
WOW how many numbers Joe. Fantastic explanation 👍
Great video! Thanks so much!
Thanks for the nice training
Thank you very much for this lesson.Again thank you.
You are more than welcome.
never thought u could solve the neutral current with trigo. Pretty cool. The 0.3 Amp difference is coming from the higher Resistance of the paper and pencil🤘That's why in the field, we never ever use paper or pencil as conductors...lol
I like that your using non harmonised colours for training.
It's all I have access to at the moment. 🤷♂️
Brilliant explanation.. Thanks
Superb explanation....
Wonderful. I liked it very mUch.
Oh what a fantastic way to explain first time I understand this thanks a lot
Nice video
You explain very well sir
Very well explained, thanks for sharing this.
Without complex number ! Really nice.
Thanks!
Thank you, your explanation easily understandable thank you very much.
Thank you!
Joe you are a good teacher. thank you
Very good explanation. My ADHD required me to speed it up a bit, but the visualization is great.
😂 Yeah it does take a while to get through, glad it helped. 👍
Pięknie wytłumaczone ❤️ bardzo dziękuje
Thanks for the neat explanation. Could you add the final piece of the equation from a design point of view: How would you select the db size required? Do you just select the highest one of the three or does the current get distributed between the phases so you can select a smaller DB. I have run across a heat treatment application where we couldn’t figure out if we needed a 128A supply or a 64A because one of the phases was above the imbalanced load. We only had a 64A supply in the factory so the decision was costly to bump it up but it was because one of the phases was higher than the others.
It was a 50/50 split on which way to go. And since we didn’t have a physical way to test it prior to delivering the machine it was a bit stressful because someone had to sign off on the decision (I do controls design and circuits as in PLCs and stuff but am not a full electrical engineer).
excellent video....
nicely done! Thank you.
Thanks and you're welcome. 😊
Perfect! Thank you!
Thanks Joe
Thank you!
You're welcome! 😊
What I understood at school it s , the current difference between phases it s wasted in to neutral. But I forgot to ask if the meter calculate that waste as used and it s in our bills.
Hi Marius, wasted isn't really the right word, it combines in the neutral and any unbalanced current flows in the neutral. The electricity bill is based on the Energy used so it's mainly concerned with the current flowing into the circuit. 👍
VERY GOOD!, a perfect explanation!
Joe am grateful for u
Amazing Joe
Brilliant Joe very clever and easy to follow 👌
Excellent video mate, do you have any suggested reading on 3ph theory, vectors etc.. looking at cpd. Thanks again. Keep up the good work.👍
Perfect explanation ❤️👌💪 thank you very much
My pleasure! 😊
Much helpful Sir
Thank you sir for your trigonometry course!
Why does an increase in load lead to increase in current? The videos have been extremely helpful and during the viewings we've come to understand that loads act similar to resistance. Therfore what causes and increase in current flow through the supposed greater resistance (hgher load)?
Fantastic
Brilliant mate, thanks for this, keep up the good work.
Will do!
Great video & well put across 👍🏻
That was a really great explanation. Well done! 👏🏻
Superb excellent
Thanks very much, stay tuned for more!
You can also use the first condition of equilibrium 👍
Brilliant.
i need the measurement of the angle :). Very clear..
Thanks! Great explanation!
You really have a gift to teach. Thanks for the quality video mate. Let's say that we have a bug house with ground floor plus 2 levels and each level are connected to separate phases of a 3 phase connection. I reckon that the ammeter would measure an 'imbalance' on the N if ground floor and 1st floor loads were switched on but 2nd floor was all off isn't? As such would that cause any issues such as high electricity bill please?
excellent video!!!
Thanks!
Can you calculate what happen to voltage phases on floating neutral on unbalanced load?, thanks!!
Thank you for teaching Trig in a way I can relate to, We were only taught how to measure a single triangle at school, it makes more sense, seeing it in relation to a full circle. That might seem weird to you, but some how I have inherited my late father nautical brain.lol
No it makes perfect sense Andrew, actually trig is just as much about circles as it is triangles. Glad the video helped. 😊👍
You can also use this formula to get the approximate neutral current: In = (phA^2 + phB^2 + phC^2 - phA*phB-phB*phC-phC*phA)^0.5
Hi Joe, I am doing a similar visual for my college students but using mob's instead of a rig with pins. However the rig is much more safe and easier, Can you tell me where to find a similar rig? Great job !!
I am eager to know, what exactly happens to the Neutral return current after it reaches the transformer from the building. Whether it is further in use?
Remember current it just a measure of the flow of electricity, it doesn't get used up it just goes back around the circuit again.
Neutral is grounded at the transformer so all that extra current goes into the earth
My power company has a 3 wire 3 phase distribution system, NO NEUTRAL. How do they balance THEIR load? Are they using a Delta distribution system? Thank you
Great info Joe. I have a related question. Will a voltage stabilizer help the system which has unbalanced loads
Clamp meter measuring current needs to be "zero"ed after turning on, before use.
Thank you very much sir
Sir Oliver’s horse came ambling home to Oliver’s aunt
Looking forward to seeing the easier method. Great video though 👌.
So was there a relationship between the phases with different loads and the neutral or not?
Am a young engineer and this video really helped me. Thanks. Umm whats the intro song tho?
Glad it helped! It's just a piece of music on my editing software, I think it's called Black House.
Which is the BEST DEVICE ( Hand-held ) as you normally use to measure values with PRECISION ???
It depends on the application really.
Fantastic explanation but i don't know it happen or not.
hello joe
i know its an old video but i hope you can answer my question
now if you want to calculate the overall power of the three phase load
should i just multiply the voltage (220) in the current for each phase ((for ex:220*4.1+220*16.1+220*8.1)) ??
or i should take into consideration the neutral current ??? if so then how can i calculate the overall power of the whole system???
Hi Joe, nice video and very straight forward calculation, I've been watching your videos. just wanna ask ,if there was no neutral conductor for this setup, will it be the same approach of calculations and where does the unbalance current path back to the source.
What would happen if there is no neutral in an unbalanced 3 phase resistive load ?? What would the currents be. Is it dangerous.