Three Phase: How to Use an Easier Method to Calculate Neutral Current in an Imbalanced Load
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- čas přidán 30. 06. 2024
- In this video we look at an easier method for calculating neutral current in an imbalanced three phase system. This is using a graphical method drawn to scale and taking physical measurements from a drawing.
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Easier method? More like "Enormous magnificence!" Thanks again for making and sharing all of these extremely high-quality videos.
Don't know what I'd without you Joe!!
Amazing as always 👍
Cheers matey. 👍
Great video explaining what we're covering at college this week. Really helps keep it fresh once we've left the classroom environment. Thanks for the content !
Good to know, that's actually my one of my main focuses on the videos to act as reminders and reinforcers for learning.
How have your studies been going?
The best channel ever... thanks Joe 👍🌟🌟🌟🌟🌟
More good stuff Joe. Thanks again
Thanks a million for that Joe.
add me to your list of students when they learned the last method. i shared your videos with my classmates and they learned just like i did... hopefully.
this video really helped. thanks much
My pleasure, it's so nice to hear that the videos help!
This is a great video, Joe but just need to watch the direction of the neutral current phasor in this video and its predecessor. In order to satisfy Kirchhoff's Current Law at the neutral point it is effectively -In we are solving for, not In. Your methods will, of course, calculate the magnitude of the neutral current correctly but the direction of the neutral phasor is only shown correctly at the end of this video (i.e. "pointing toward the neutral").
That's a really good point actually, I took it to this point because Level 3 electrical requires you to find the magnitude not the angle, but I'll do another vid explaining the next step. Thanks for commenting. 👍
@@JoeRobinsonTraining really wish I’d had access to your vids 35 years ago when I was training as an electrical engineer. You are very good at explaining these concepts.
Cheers mate, much appreciated!
This method also gives neutral current angle (assuming resistive loads) without any calculations
The neutral current is actually reversed from how he drew the vector in this video. Neutral current needs to cause the current among all four wires to add up to zero, which means it is the reverse of the vector sum of the three phase currents.
There is another method, but it's a long calculation, Pythagoras based.
Brilliant and very easy!
Thank you! 👍
Thanks Joe, well explained. Apart from "exam for exam's sake" why would you inflict method 1 or 2 on anyone? Presumably method 1 gives the definitive "correct" neutral current, the other two methods being an acceptable "rule of thumb"?
Method one combines accuracy with a visual representation of what's going on which is the best of both worlds really. There is another formula that you just stick the numbers in but it doesn't generate any understanding of what's happening in the circuit.
Thank you it's awesome
Joe - great video. In your experience, has an exam board every expected students to calculate neutral in the most complex way?
That is a good question. Not in recent memory but I'm struggling to go back over all the iterations of the electrotechnical qual. 🤔 Currently I believe C&G state either method is acceptable. EAL, I think, ask for a phasorical method. I'd need to confirm with the documentation though.
These are brilliant tutorials, however i would suggest for both accuracy and speed using AutoCAD is a must if available.
Good point Angelo, thanks, unfortunately it's not always accessible in an exam. 😕
If you have access to a calculator that can do complex numbers using magnitude and angle, it gives you exact results. 4.1
I will stay to the end, and know this is for students, but I hope you break out the polar features of the calculator and just get the answer.
How do you calculate the neutral current when there is a PV system and there is net energy export on one phase and import on other phases? How do you draw the vector when it represents net energy being exported to the grid on a phase?
For example, let's say there is 10A export on L1 / 18A import on L2 / 0A on L3. I measured about 25A in the neutral in this situation with a clampmeter but that seems very high...
PS: I know this video was posted 4 years ago, but thought I'd give it a shot anyway...
Does anyone here remember the old C cert ? Sadly it seems to have been forgotten and often overlooked these days.
Little bit before my time I'm afraid, pretty sure I would have loved it though from what I've heard.
It was this stuff Joe, I've still got my old notes and I checked. I really like your channel and I'm watching your vids daily. Thanks for making these vids, please use a pen, I have to really strain my eyes to make out the pencil😄
@@Rob.P974 ah good to know, suggestion on the pen noted, cheers!
Hi Joe, just catching up with your training videos. If i were to use CAD with this method, not for an exam of course, would the answer be spot on and as good as your first example by calculation.
Absolutely it would, within the limits of the software. Great application, well done, I may have to do a video on it! 😂👍
Никогда до конца не понимал эти векторные диаграммы, а вот тригонометрический метод прост и понятен, и точнее....
Very easy to calculate the neutral current without all this drama. In a balanced source (I'm assuming you have a balanced source) The source currents are 120 degrees apart so Line 1 is 4
Not sure it could be classed as drama, but thanks for another option.
😍
I don't understand in what situation a phasor diagram method would be preferable to a vector diagram method (your triangle method). I have always been taught through school to use the vector diagram for graphical representation of resultant forces.
Just seen the phase diagram drawing of the star and delta 3 phase motors. Now I understand! When there is a lot of vectors of a single variable the vector method is easiest, when there is loads of different variables the phasor method is easiest to work through.
Thanks for commenting and asking questions. And thanks even more for answering it yourself!
Hi, why did you use 60 degree for the 2nd method? why not any other degree?
Sir what will happen if one CT is reversed and the other 2 ct ok
What will plhappen in current ?
vector analysis?
In the last method, you placed the arrow at the wrong end of the neutral current vector.
This method used for voltage 22kv?
I've never tried it for high voltages but I imagine the principle is the same. 👍
Why not use calipers?
i was wondering are you an engineer?
Let A, B, C the currents, we have I = Asin(x)+Bsin(x+2pi/3)+Csin(x+4pi/3). This can be simplified to sqrt(A^2+B^2+C^2-AB-BC-CA)sin(x+Φ). So, sqrt(A^2+B^2+C^2-AB-BC-CA) is the formula.
Theres an even easier way 😉
Check my other videos and let me know if I haven't covered it! Cheers.
You like to draw. You could just put the values in a program. Nothing is actually learned from these drawings. Maybe you were supposed to be a draftsman.
I do like to draw. I could have put the values in a program. These drawings help you visualise how the differing currents affect each other. Maybe I was supposed to be a draftsman!
Just say Amps. Ffs
Either way is acceptable. 👍