Transformer basics--theory and code
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- เผยแพร่เมื่อ 28 ก.ย. 2024
- This video shows the fundamental concepts of transformers. It discusses magnetic induction, resistance, reactance, voltage, and current. It also goes into the NEC requirements for transformer and conductor overcurrent protection.
Ryan, your level of teaching is the greatest!! Keep up the good work!!
Great videos. I appreciate the content, humor and style you use to get the code information across.. I recently passed my electrical inspector exams here in New Jersey. The big lesson from my 25 years as a contractor is that you should never stop learning.. Thanks.
Your the best at explaining everything. I swear out of a million electrical videos I watch on TH-cam I always understand things better from you . Thank you 🙏
You are doing a great service for the electrical community sir. I appreciate what you are doing. I feel smarter after watching your videos.
I'm a 3rd year apprentice in California. Thank you so much so putting out these free videos because I need to rewatch multiple times
I waited for the wife to go to bed, so watching this at 1030 at night.. and not bored at all.. and wide awake.. you do such a great job and I really enjoy watching your videos! Thank you as always
Having gone through an IBEW apprenticeship, the two spools of wire is the best basic demonstration of a transformer. It really gets the point across.
Love that 3-phase math trick (5000/ 120). Never heard that formula in a classroom before.
I remember the first time I heard it. Seriously blew my mind! I've had so many people thank me for teaching that. It's a concept that just isn't taught.
I've been using it (secretely) for many years but never seen it mentioned in any literature. It's just common sense but not commonly used for some reason.
Finally, exactly what is was looking for. Great video, thanks!
Happy to help.
i watch on my phone for 3 minutes and i def got this one saved for later, cool demonstration
Thank you so much for this material. You make it very easy to follow.
Great stuff! Great examples and well presented.
This is great. Going to suggest the union hall show some of your videos to the school.
Hi Ryan, I've seen you in Mike Holt's videos, and I'm very impressed of your knowledge. I've watched almost all of your videos. They are all great! I'm looking for practical info regarding Title-24 (Lighting Requirements, or diagram for electricians or general contractors). I don't see alot of videos related to the Tittle 24 code, and I think it's will be very beneficial to electrician as well as general contractors. Thanks again.
Do you have a topic motors related; because I love the way you do the presentation
Thank you Ryan. I am learning a lot from you. Great instructor.
It's always good to review. I wish we had the internet 50 years ago. Sitting in my home spare time going to class not wasting time in traffic or going to a class. Next class should be on V F D
hi .Ryan we need a video about Objetionable current and what is the best point to bond neutral and ground in the large swtich board in building.CASANOVA EC
Ryan I watch electricity videos in Spanish, but nothing compared to this teaching you give us. Thanks God I learned English. I seems to me that I have seen you working with Mike Holt.
Hi Miguel. I used to write books for Mike, and I probably did 50 or more videos with him from 2005-2017.
@@RyanJacksonElectrical Awesome. Ryan I do have a question. Why does not the NFPA 70 NEC add the nomenclature TN-C-S to identify the type of grounding system the NEC implement from the other countries grounding systems TT, TN, IT, TN-S TN-C? Like I feel the American grounding system does not have a particular, peculiar or unique way to be identified, hence a lot of confusion is created in regards the american system in other countries. I sent the proposal to the NFPA, Do you think they will make the update? Because the grounding systen the NEC uses corresponds to a TN-C-S earthing arrangement or configuration. IEC 60364. NEC 90 C 1
@@miguelac6872 Honestly, I've never heard those terms.
Ryan your demos are great. I really appreciate your vid’s.
I am writting from colombia. What a great job mister Jackson. God bless you.
Thank you sir!
Ur great” u touched up on a lot of mike misses” don’t forget generators” sum guys still don’t get it.
Very educational. thank you, although I'm going to have to watch this at least one more time to grasp all of the numbers you throw out . Which is great cause I can always go back if missed anything.
I've been a sparky for a few decades. IBEW Local 3 NYC. I have worked in many highrise buildings, subways,bridges, tunnels,manholes. You name it I've been there.
Many times we work from blueprints that were designed by engineers architects and buttheads. With that said I normally don't have to carry a code book in my tool box.
I'm more of an installer rather than a designer.
Your 1 to1 ratio or 480 v to 480 v transformer s I have used in elevator machine rooms. I questioned the elevator guys about that and they told me that's how they get clean power for their electronics and computers .
We still put 2 disconnects because the specs call for it. You have have to give the customer what they pay for regardless the code,unless it's illegal.
We also use greenfield or sealtight to change over to go into the transformer. (For vibration).
Makes no sense because the coils are mounted on shock absorption pads from the manufacturer.
So if mounted to the floor we have to put rubber pads and if hung from the ceiling we have to put spring shock absorbers. ( With flex conduit). Thank you
Ryan I will finish the trim in ur house if u come finish my electric! I love ur videos. Thanks and please keep making!
Excellent explanation 👍👍👍
This video has become mandatory viewing for my apprentices and recommended for my colleagues in the service department...
Sometimes a back to basics refresher is absolutely advantageous...
Simply superb sir, we thank you. 🫡
Impedance, resistance, reactance do you have an explanation of them? That differentiate them
Impedance is the total opposition to current flow in an ac circuit. It consists of resistance and reactance. Resistance is a physical property of the wire, and reactance is (for this demonstration) a function of the shape of the wire, that being a coil. It's a bit more involved though, and requires more explanation than I could do in a TH-cam comment. Sorry
@@RyanJacksonElectrical well said, I’ll just do my research about reactance. I came across Lenz law about eddy current. I’m subscribing to you right now
@@johnquilla8236 Resistance (R) is a property of a component that dissipates power when subject to a voltage difference across it, while reactance is a property of components that store energy and release it at a later portion of the AC cycle, like inductors and capacitors. Resistance (X) only depends on the geometry, temperature, and material of the resistive component. Reactance by contrast, depends on both geometry and AC frequency (f). For a capacitor, reactance depends on the capacitance (C) as a measure of its electrostatic size, and equals -1/(2*pi*f*C). For an inductor, reactance depends on the inductance (L), as a measure of its magnetism, and equals 2*pi*f*L. Resistance causes a voltage drop across a component, while reactance causes a shift in phase.
Impedance (Z) is a special way to combine both reactance and resistance together, in order to analyze series and parallel combinations of any of the above devices. It enables you to "black box" these components as impedances, and add up the impedance terms as if they were all resistors, using your series and parallel formulas for combining series and parallel impedances. Then you substitute the expression for each component's impedance to evaluate it further.
Mathematically, impedance is an application of complex numbers, where resistance is assigned to the real component of the number, and reactance is assigned to the imaginary component of the number. In pure mathematics, the imaginary unit is called "i", but this is spoken-for to stand for current. So electrical engineers opt to use i's next door neighbor, and call it "j". Impedance Z = R + j*X. Magnitude of impedance is a Pythagorean theorem combination of R and X. You can think of R and X as perpendicular vectors that add up to Z.
This was very helpful, and interesting. I'm wondering what current flows in the primary when the secondary is not hooked up. They say with a manufactured transformer, it should be no more than a few percent. Does an open secondary causes a dramatic increase in impedance because of the induced voltage drop across the secondary windings? If you were to scope out the secondary voltage, would there be a huge back emf voltage spike because there would be nowhere for that secondary current to go? Presumably a home made transformer, with inefficient energy transfer and weak core, more primary current will trickle through when secondary is open?
Thanks! This helps a lot. So, a transformer is like an automatic transmission torque converter where the transmission fluid is electromagnetic field. It's crazy that either one of them work.
From what I have read inrush currents last a few cycles, the maximum inrush is often touted as 10X the rating of the transformer, in my experience 4x to 6x is normal for a standard off-the-shelf dry type transformer. Where we have seen inrush as high as 14 times is with fast transfers of ATSs' with no in-phase monitors. The ATS transferred back to the utility with the two sources out of phase, which resulted in a very high inrush on the utility source.
I liked your video so much I tried to make a transformer like yours but it trips the breaker because it’s a short circuit. How did yours work? I wired a coil of #12 thhn with one end to neutral and one to hot and plugged in to a switched power strip so I could turn on and of quickly and then another coil to lamp holder. It trips instantly without ever staying on at all. So are you not using a breaker?
I am definitely using a breaker. It will pull a lot of current, so you can't leave it plugged in very long. I don't leave it on for more than 10 seconds.
Hello there! Thanks for sharing, im currently studying at LATTC and this info is very helpful!
Glad to hear it!
Ryan you are a great teacher love your videos
Ryan did you measure the voltage on the secondary?
Thank You Ryan! You are a great instructor
How does that first spool of shorted 12 awg not trip the breaker?
Inductive reactance.
Awesome video!!!!!Thank You!!!!!
Keep’m coming!
53:22 mark i thought you could on 3 phase systems cheat by dividing the kva by 3 as well as the primary voltage by 3 then devide kva by voltage for current? i got 468 amps
Bro you and mike holt I hold to high regards. Do you have any tips on what I should do to attain more knowledge.?
Thanks a million times for sharing!
Thank you Mr. Jackson
m
Great video!! I have noticed that most iron cores in transformers are laminated is for heat diapason purposes?
Does the wire coating affect anything?
im a little lost when i do the 3 phase transformer math, i get a different answer, i get 225 kva/480*1.732 = 811 Amps What am i doing wrong
Thanks Ryan Jackson I really love this topics
I believe 3phase service such as a 120/208 grounded b phase uses only 2 transformers. I would like to know more about that type of system.
A 120/208 system is a wye-connected system, which cannot be done with two transformers and would never have a phase grounded. With a 240V delta there are some options, one of which is grounding a phase. A delta can use two or three transformers. I cover the topic in this video: th-cam.com/video/O-1S93wQN5Q/w-d-xo.html
ok i got it ,,,i kept reading the other comments and you explain it think you
27:25 I definitely want to magnetize my socket wrench now lol
First thank you for the videos you put out they are a huge help. Second when do you use the Primary only method and when would you use the secondary and primary method? I have recently switched places in my company went from doing service and TI remodels to industrial work, so I'm doing alot more work with transformers.
I only use pri.ary plus secondary if the primary only won't allow for inrush (which is to say, never).
If you're I stalling transformers in parallel you have to though.
great video, I learned a lot from this! I have a quick question, so creating that separately derived system since the spool of wires never touch each other, is the new secondary panel technically a new service panel to where you have to bond the neutrals and grounds together? or in the transformer are they bonded together with the primary side? I hope that makes sense! lol thanks
Not a service (services only come from utilities), but you do have to create a new grounding/bonding system.
Awesome video Sir!
Hi Ryan
Can you explain to me the note 3 for Table 450.3 (B)
Thanks and love your videos
why did we divide 225,000 by {831} and 225,000 by 360 ? thats whats confusing me.
Because it is three-phase. You take tge line-to-line voltage times the square root of three (1.732).
Great video
12.5 Amps is greater than 9 amps on the secondary it should be 125%. @52:15
I really really like how to teach, but when I saw the spools of tthhn I laughed because it just looked like ok! Look at it! & the rachet lol but at the same time I admired & learned a lot! In the end thank you thank you
LOL. Thanks for the compliment. I'm sure by the end you realized that I used such a simple model for that exact reason...to show how simple it is. Just a couple coils of wire and lots of physics. :)
Also about customer own transformers 1000 feet away does voltage drop come into play.
It's something that needs to be considered in the design, for sure. That's a lot of impedance.
Thank you
How did you come up with 831 for 480 volt and 360 for 208 volt. thanks
208 times the square root of 3 (1.732). Same with 480.
Ryan Jackson that you for clarifying you are awesome 😎
Hi Ryan, the input voltage in the THHN wire is 120V?
Yes.
@@RyanJacksonElectrical I just did this and got 33v. Primary 120v / Secondary 33v. Also did 12vac primary And got 5vac secondary. This is amazing!! Thank you very much!!
@@alexandrebraga1298 Awesome! It's such a great way to learn about transformers.
My understanding is that a transformer is a device that transforms or changes voltage (step-ups or step-down) 🤷♂️
Usually, unless it is an isolation transformer with a 1:1 turns ratio.
Thanks!
@@martymcenroe6622 Thank you!
💯
I'm paying attention
Thanks great explanation
👂🎧🧠
19:51, the last bullet point is not true, if you have a resistance of 1 and a impedance of 3, then the formula is 1+jX=3 where X is your reactance. If you do the math:
sqrt(1^2+X^2)=3
solve for X and you get a reactance of 2.828 ohms
I don't cover the square root of -1 for simplicity's sake. I agree this is not 100 percent accurate, but, in my opinion, it gets the point across. I also still use the Neils Bohr model for atomic theory for the same reason...for the purposes of this this discussion it is "close enough."
no worries, I'm just here to learn all these rules since I'm only 1 year working as an electrical engineer in a MEP firm, you do an amazing job explaining rules
@@RyanJacksonElectrical the old famous 220, 221 what ever it takes, 2.8 or 3....whatever it takes. Love your videos, I graduated 21 yes ago and love the refresher and the code knowledge! Thank you
I thought this was Matt Damon holding a tool for a split second.
LOL I used to get that so often. 🤣
@@RyanJacksonElectrical
🤣.
Good video my friend!!
👍👍👍
Saved to watch a few more times to absorb everything.
I’m a master and still learning” don’t you stop 🛑
I'm in the trade 50 years love reviews. Always learning.
The last time I saw a transformer demonstration like this was in 1997in trade school at Atlantic vo-tech , Fort Lauderdale. Thank you for that demonstration and excellent commentary. Great job Ryan!
Saw it there from Steve Owens RIP
Thank you for these videos they make a world of difference for all of us
The way you use the word "efficiency" in this video is pretty common, but also quite inaccurate. In common speech "efficiency" has come to mean something nearly equivalent to "good" - but it should be used to mean (in this context) the percentage of real power going into the transformer that comes out the other side. Your loosely coupled transformer has both a low coupling ratio and low efficiency. . Efficiency and coupling are two different things. But It is entirely possible to build a transformer that has deliberately less than 100% coupling of the magnetic flux, and yet still has very low losses in terms of energy loss. In which case the voltage ratio can be, as you note, very different than the turns ratio. In fact the (unloaded) voltage ratio is the turns ratio times the coupling coefficient.
Commercial transformers of almost any size or power rating (excluding special transformer like ferro resonant types) have coupling ratios of 99.9% or better, which means the unloaded voltage ratio is pretty much exactly the turns ratio. Because the windings of both the primary and secondary have some resistance, the voltage under load will sag, and the voltage ration will be less than the turns ratio. So to achieve the desired voltage ratio when under load, the secondary may have a few extra turns so that 480 in makes 240 out when under load.
Pedantic note #2: There really truly are 3 phase transformers that are NOT just 3 single phase transformers in a box. It's a bit tricky to wrap your head around how it works, but you can have a single unified core with three legs, and primary and secondary windings on each leg, It use significantly less total iron for the same kVa as having three separate transformers. Sometimes three separate cores are preferred, as you can lose phase and the other two can still work, or it is more flexible to have a single phase transformer with a stinger. But for the least cost per kVa
a "real" three phase transformer wins. I was an electrical engineer for 20 years before I learned this, when I got tasked with designing AC power conditioning and regulating products, instead of the pro audio product design that had been my specilty up until that point.
Lets say we have a single phase 37.5 KVA transformer, (240,120 V ) the secondary can deliver 156 A total, the question is, when a ground fault occurs between a hot and the EGC, how come the amount of current is way to higher than the nominal current the transformer can deliver 156 A? I know that the EGC is a low impedance path but where does that super extra amount of current come from?
The thousands of amps that you describe, which are the result of a short circuit, is what we would call the "available fault current." That number gets smaller and smaller the farther you get from the source (utility, for example) because you are adding resistance with the wire and transformers that we are installing. The number is high because the impedance of a direct short circuit is very low, but, again, the farther you get the lower the current will be (generally speaking). If you search for "bussmann fault current" you can find a lot of good information, as well as a free online app that you can use to see how it plays out.
@@RyanJacksonElectrical Thank you very much.
Good work Ryan, I see you learned more on Mike Holtz Seminars lol, like Mike holtz Said in one of the vídeos. "Mike holtz is going to disappear one day", we need more Leaders, and i see you are one of them, Congrats, and keep on going. Thanks l like to watch your videos. Atte. Jorge Flores.
I have a question.
On a 125 amps 230v. 3 phase once I saw this which it looked a transformer each line went & came out for each phase, are they like rectifiers? Nit sure.
Ryan or anyone?
Thank you or you can email to phs11@optimum.net
I can't thank you enough. You clarified even for a beginner like me. I love how you show everything with great examples and pictures. It's as if I am doing everything practically. I never get tired of watching your videos. Thank you very very much. God Bless You!
Really informative information sir. I really appreciate the knowledge you bless us with. I always like to further my knowledge with continued education. I’m curious do you offer any online classes?
I appreciate everything, this is some thing I was looking for.
one point if you can clarify i see in my factory many single phase 480 to 120/240 transformers so the panelboard must have a main or a fused disconnect before it cause its not single voltage.
Transformer secondary cannot in this case be protected by primary correct? Or for almost any separately derived transformer power system in Industrial or commercial?
Great demo showing the effect of reactance by using screwdriver and heavy spanner . Heavy spanner gives more induction/reactance so less current.
At 17:39 in video you measured the max current. Was this the inrush current or normal steady state current ? Are they the same here as you just have a spanner so poor induction taking place ?
The screwdriver is longer than the ratchet, when you used that as the core your amperage increased because you coupled more coils in the primary.
thanks a lot
Hi Ryan, how can I get the DeWalt reference book.Pdf
Dayum Ryan Jackson!! Where were you when I was in 2nd year??!!
great info Thanks Ryan
It'll be a long way if you don't know where the breaker is located
Hello Ryan. Tanks for this master class.
That’s interested and simple to understand
Hi, I like your lecture . Thanks
Awesomeeee
Wow.. Great explaination..
Excellent - thank you
Good demonstration...!!!
Very informative thank you!
Badass teaching
Mr Mike brought me to here. :D
Is interested