What is the Primary Side vs the Secondary Side of an Electrical Service?
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- Опубліковано 26 лют 2023
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One of the things that many new electricians (even veteran electricians) struggle with wrapping their heads around is how a transformer works and what is the difference between the primary and secondary side is. Seems like it is just some voodoo magic! In today’s episode of Electrician U, Dustin dives in and gives some explanation to how it all works.
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A primary transformer is simply a piece of equipment that the utility company uses to step down their voltage to a usable level in a building. It could be any building- a residence, a 3-story commercial building, or a sprawling industrial site. The voltage that the utility uses is generally MUCH too high for us to be able to utilize in almost all building types and requires it to be stepped down to a usable range.
Remembering from previous discussions that electricity travels in complete loops. Transformers are no different. The cool thing about transformers is that it uses the relationship between the electrons and magnetism to do its thing! At the utility plant there is some type of generator starting the process. Wires leave the generator (whether it’s a coal fired type generator, a wind generator, even a nuclear generator) goes thru one side of the windings of a transformer, and back to the generator creating a loop. The voltage that is operating at this stage is very high probably at the 150kv range! Within the first transformer (or transmission type of transformer) there is a secondary coil that isn’t necessarily touching the primary coil, but the electrons get moving by the magnetic fields caused by the first coil and a different voltage is produced on this secondary side- probably in the neighborhood of 7200v. this is considered a distribution voltage range. Still too high for normal mortals to utilize but can be run thru neighborhoods to distribute to either the pad mounted transformers on the ground (those green boxes you see when driving along) or the pole mounted transformers. But we are still not quite done yet!
From those distribution transformers, again, there is a primary and a secondary coil in it. The primary coil is a complete loop between the previous transformer (the transmission transformer) and the secondary coil is a complete loop between the transformer and the building it is serving. As electricians, when we set a panel, we are simply putting it in the middle of that last loop! We don’t normally have the wires from the transformer going straight to the load, but rather have a panel in between the phases so we can control things and turn things on and off as needed. Again, electricity travels in loops, and once we understand that concept, things tend to become much clearer on how electricity works!
A closely related question would be what is the difference between the pole mounted transformers and the green pad mounted transformers we see in newer or higher end areas. Nothing really- its just a different way for us to get power down to a useable level! The pole mounted transformer system is considerably cheaper and easier to install. Drill holes in the ground to slide the pole in, sling some wires in between the poles and voila! But you do end up with the unsightly poles/wires to be seen by everyone. The pad mounted type is much more pleasing to the eye but requires considerably more labor. The ground must be dug out or horizontally drilled, conduit must be installed, trenches must be backfilled and THEN the wire can be run in between. Again, considerably more labor intensive, but much more pleasing to the eye. In addition, it also keeps the wire out of the effects of weather and away from the general population!
We hope this has been an insightful look into the primary and secondary sides of a transformer. Is there a topic you would like to see discussed on Electrician U? Leave us a comment in the comments section and let us know. Please continue to follow Dustin and Electrician U as we are constantly updating our content to assist our followers in becoming the best electricians that they can be.
#electrician #electrical #electricity #primary #secondary #side #service
In practicality what you're saying is correct but specifically primary side and secondary side is sort of relative to the device. Generation plants generate anywhere between 20kv and 110kv and they usually have a STEP UP transformer to increase the voltage to 345kv or even 500kv for transmission. In that specific transformer (step up) the primary side is the lower voltage side and the secondary side is the higher voltage side. In the substation they take the higher voltage and step it down to distribution levels with STEP DOWN transformers. So the primary side of those transformers is the higher voltage and the secondary side is the lower (345kv->138kv->27kv...). You can tell which side is which (usually by the sizes of the bushings/insulators) on top of the transformer. The higher the voltage the bigger the bushing. What's interesting is that since Voltage and Current are inversely proportionate the transmission lines (345kv) has lower current. That's why on the transformers the bigger bushing (voltage) will have smaller tabs (for current) and the smaller bushing (voltage) will have bigger tabs to accommodate for the amps.
And as someone else mentioned here the number of loops/coils in the transformer determines the ratio of stepping up and down. For example if the primary side has 10 loops and the secondary side has 100 loops it's stepping up the voltage by 10.)
The grid is a fascinating thing.
Yeah, the generation plants have to increase the voltage, because this reduce the current, and therefore, this reduce the loss of energy in the transmission.
I rarely comment on videos, but I just had to do so here. I appreciate you big time for all of these videos you consistently put out, honestly. I started my apprenticeship with zero experience & these videos have been helping me soak up so much of the stuff I run into @ the job site (& just electrical concepts in general). Nothing but straight gems. Thank you.
Really would be awesome to see a video on the old school 2-phase systems and Scott configs. Don't see much on the risks of imbalanced loads vs balanced loads and such. If you haven't done a video on this PLEASE do so!
Some extra information on transformers - the coils inside are typically coiled at a specific ratio to create a specific voltage. (Ex: 7200v:240v is a 30:1 ratio - 240v:24v is a 10:1 ratio)
Im not an electrician, im an HVAC service tech who works with 240v and 24v 😁
Of course.
Thanks 🙏🏽
Could you show us how they are wired inside, the wye and delta configuration
I follow you from MEXICO good videos
Excellent explanation
Great explanation. I am blessed to have a underground transformer in my yard. Was super east to get my 400 (320A) SERVICE. got to love my cps
Premises. But GREAT vid again. Thanks. I used to teach a selective rotation of Industrial Arts and one of the sections was about electricity. My students had to build a 4 foot wall (each group) and then wire that wall with a GFCI branch, a switch, a light, and everything had to work. Thanks again.
Justin you are a great teacher. Keep up your teaching videos. Thank you.
*dustin
Great lesson.
Thanks for explaining the pole transformers.
Nice. We just talked about this at a grounding class and I didn't fully understand primary and secondary. Thanks for the detailed lesson. You da man lol
Dustin
Dude I’m not gona talk about electrical topics at all
Perhaps nobody has realized or perhaps we all are agreed that
You are a amazing human being
For sharing your knowledge
I’m pretty sure that you never imagine the magnitude of the growing of your channel
I doesn’t matter if you make money doing it or not
It’s just your Essence
God bless you
Second that!
Hey, Electrician U, you should gives us a tour of all your Electrical Books.
I sympathize with trying to spell certain words without a built-in spell-check. Shows you how much we depend on Microsoft Word.
Great timing for me.. im ganna check out you continuing education. Hope you have Ohio
Great video
I love your (perhaps unintentional?) reference to the brouhaha over ICP's "Miracles". And by the way, we have a pretty good handle on how angry pixies moving through a conductor induce a magnetic field and how this field can be coupled to another conductor, inducing the movement of other angry pixies. We even have a pretty good idea of how the angry pixies become transformed into force communicating pixies and back.
You've got your transformer winding illustrations back to front; the side with the higher number of turns would be at a higher voltage. Might want to add a note to the describey about this.
Thanks 😊
Thank you so much for your videos they're very educational I've learned quite a bit. Could you please do a video on how to tighten up the boats that's at the top of your breaker panel your box in your house how to tighten those bolts up safely without getting electrocuted or cooked.? Even though you turn off all the breakers I can only hope everybody knows that the main wires coming into your electrical panel still has electricity on them..
It may be cheaper in the short run to do pole mounted lines, but I have to imagine it's a lot more expensive over time having to replace and repair the lines all the time in places that routinely get snow, freezing rain and lots of wind like we do up here in the north.
I live in michigan and we just had an ice storm that took out a bunch of transformers and power lines and the power is still not back in some places 4 days later northern states should definitely start burying electrical equipment because like you said it has to be a lot more expensive to constantly maintain it and fix it
@@gagebell5602 coincidentally, I'm also in Michigan. Hauled my generator out because I pretty much expected for the ice storm to knock out the pole mounted lines on my heavily wooded street. Got lucky and it didn't, this time.
Do not forget hurricane prone areas. Here in Florida nearly all new construction uses underground services.
Yes, . . . . . .The state of Texas is very familiar with winter conditions causing powerline outages.
@@gagebell5602 newer construction tends to have everything buried underground but they’re not gonna go back and start modifying everyone’s existing installations. There’s too much stuff already established and built up. It would make it a nightmare to make it work.
funny story. I am doing a remodel. Phases were shifting under load. Each leg was alternating at 118v, 90% of the time. Draw a load on it, one leg would drop to 106v while the other leg would increase to 130v. the utility company would not listen to me telling them it was a neutral issue on their end, kept saying it was inside the house. Long story short, it took them 4 trips/4 tickets over 2 days to find their broken neutral at their own pole.
Would you make a video on your options for dealing with a house that doesn't have a ground and what code there is on replacing the two prong receptacles with three prong? Additionally there seems to be a lot of people online discussing adding a GFCI as a solution.
I live in a house that was built in 1928 and have the same setup. No ground. Would be interested also to see Dustin's ideas.
if your house system is so old that there's no ground rod and only 2 prong outlets, it may be time to look at a total revamp of the system, starting from scratch with everything new.
@@rupe53 so the current house is a rental and I won't be doing that lol, but the owner at some point replaced all the receptacles with three prong outlets. I originally noticed it when my UPS wouldn't work and gave me a site wiring fault light.
I just figured this would make for a good video and potentially help home owners understand what is involved if they decided to hire someone to fix this.
@@rupe53 I would like to do that in my 1950 built house. They all had 60 amp service back then, with maybe six 15 amp and maybe 2 20 amp circuits. These were type S plug fuses. About 20 years ago I had 100 amp service put in. Of course three prong wiring didn't start until the late 60's. At least it's not Knob & Tube. There are millions of homes in this country that have this and people don't have the money to fix it.
@@reallunacy ... I would also like to hear Justin's point of view on that, even though it's spelled out in NEC to allow that conversion. I suspect your case has something simple like the hot and neutral are reversed. The UPS generally won't see the ground.
Love your videos you forgot to draw the neutral wire I feel bad for all the lights and appliance running on 240 😅
This guy has a shit ton of knowledge which is well power I'm here to learn learn learn for sure in whichever way I can and I feel like I do when I watch electrician U videos
Actually, power stations tend to start at low voltages, usually 2.3kV to 30kV and have step-up transformers for transmission lines, usually 115kV to 765kV.
Can you break down OCPD for the primary and secondary?
Can you go over switchgears transformers and distribution panels
The other distinction is to the meter and behind the meter. Some areas we pull the wire to the meter, others it's he utility that does. In any case we pull everything behind the meter.
I live in the Middle East and I have a table fan that works with electricity 230 V AC 50 HZ.. If I brought it to the USA and ran it on two phases, each of them 120 V AC 60 HZ.. Does it work well or does it burn...? Thank you
What kind of whiteboard is that?
I’d love to buy one
Question: isn’t the primary coil in the step down transformer suppose to be more that the secondary side? 4:24
Does North America do SWER (single wire earth return) from YOUR step down transformer to the SUBSTATION? Or do they use a NEUTRAL back to the substation? thank you
It is used but mostly only in rural areas. Not something that the vast majority of electricians here will ever touch
Wouldn't the primary side have more windings then the secondary side if they are step-down transformers? The schematic seems to show the opposite...
you're right
Question: In transferring power, is there an efficiency difference between induction and conduction? That is, because the wires aren't touching in a transformer, is there less power (W) because the current flows thru the air instead of copper? Think Magne Charge.
2 years in a row I've done your continuing education and neither times were videos of you, it redirect to a different site
is there in USA 🇺🇸 this thing (Earth Leakage Circuit Breaker) ... ?
Power and power out baby the simple as that
How does it work with tap boxes
Premises*
In my area the 7,000 volt primary is connected as an auto transformer because the cheap lazy PECO / Exelon is two cheap to run two high voltage leads to their distributions transformers even when 3 phase is on top of pole. So every house has current back feeding this halve ass connection thru the copper water service , steel gas pipe and even the cast iron waste pipe. Have measured over 1/4 amp of current flowing on the copper water service with the meter removed & the main circuit breaker turned off. Of course bet at least 10% of the aluminum ground wire that connects to primary, secondary and metal transformer case to the ground rod at bottom of pole has at least 8' of wire stolen and takes them.months to repair it. These ground rods are absolutely worthless in the winter time because most have at least 20' of concrete then 50' of blacktop.
DUSTIN, try to make a lesson about various types of LOADS that electricians would need to know about and how different LOADS will draw different currents using reactive power, applied power, apparent power, true power are all based on the LCR loads. Electricians should know about different types of loads because not all loads are the same. Some loads will induce Harmonics on the AC 120vac line which electricians should know about why certain loads will add harmonics. The transformers secondary winding will "reflect" these harmonics back to the primary side which will backfeed into the AC outlets so all the AC outlets that are connect on the same breaker path will have also harmonics upstream and downstream because all the AC outlets are connected to the same breaker, this is not good and needs to be fixed.
What causes Transformers to explode? It seems we hear of at least one going off every year in our neighborhood.
Speaking of circuit breakers…….. can a GFCI be used as a circuit breaker? I have a 20 amp circuit going out to a shed. The first termination in the shed is a GFCI. If I wanted to add/modify any electrical components in the shed (“downstream” of the GFCI), can I just trip the GFCI? Or is it safer to go back to the house and open that circuit breaker?
They are rated a specific amp rating, similar to breakers (well more like fuses). If they over heat/over amp due to surges, shorts, etc - usually the porcelain fuses blow.
generally speaking, transformers are low on the list for explosions. What most people hear is a fuse letting go. They have a small explosive charge that makes them physically drop down as a visual indication of being blown. It sounds like a gun shot.
GFCI"S are double pole breakers. When they trip both the hot AND the neutral open, thus there is no possibility of current back feeding.
@@davidmarquardt9034 ... the GFCI in that guy's shed is an outlet, not a breaker. The question is about that circuit being dead if the GFCI trips. The answer is yes, but I wouldn't be working on that branch unless I knew the breaker was off.
Please explain:
I basically get how induction works, but what is so magical about coils that there isn't a short circuit?
A coil is just a wire spun around a spool. If you stretched out that wire and put a "hot" and a neutral charge at either end you've have a short circuit. However, if you coil the wire it creates a more intense magnetic field and somehow doesn't short out.
Why?
Because of the coil configuration, the current running through it creates a magnetic field that opposes the current being passed through it. By nature, inductors resist a change in current. This effect is exaggerated by motors, because of the spinning rotor the magnetic field can cut the lines of flux and resist a change in current even more and the motor can do "work" while spinning. Though if you keep a coil stationary and don't have a way to disapate some of that current, the coil will become saturated and burn out, this is why a motor must spin or rise current draw will become too high and saturate the windings. So just think of it like this, if the coil isn't doing any work, that excess energy has to do something and it will be converted to heat unless doing work like driving a motor or any other load, otherwise yes it is just a short circuit. Conservation of energy my friend.
@@BushyBrowsHD First off, thank-you!
Electrician dude was talking about transformers (primary secondary) and induction where the windings of the coils are different to create different voltages.
If a primary coil is feeding a secondary coil and the secondary coil has no load, what's to stop the primary from frying?
I almost heard you suggest that the magnetic field works sort of like an insulator. As more energy is bled off the more current can flow through the coil.
Am I all wet?
@@nhtom8 transformers are tightly wrapped coil windings around a ferrous core, this increases inductive reactance which increases impedance, which is similar to resistance and works to oppose change in current.
Transmission is the "big" primary.
premises
I also hate trying to remember how to spell maintenance
The most primary circuit is the transmission circuit, or primary 1 or primary 2, just kidding, don't know if there's more professional term, than transmission lines.
Soooo your telling me that current has to complete a circuit but if I grab both legs coming in to the house and touch it Together it will blow up?
How much can you make in US dollars as a apprentice, license electrician and master license electrician?
that's going to vary widely, depending on your area. Starting pay might be in the 20 / hour range but after a few years (and license testing) you might get $50 - $100k working for someone else.... but that depends on where you are.
Okay let me rework this I know from the substation the wires come over head and they have distribution wires the 7,000 volts okay now when he gets to the subdivision how does it get underground again so that they can run the underground to get to the green transformers on the ground
Discord
Had to google it and first result I found told that at least one of our nuclear plants in Finland has 20 kV main generator (with nominal current of 31.7 kA). That voltage goes to 20 kV /412 kV transformer to be fed to the national grid. There's also 110 kV grid, which is used to supply startup voltage for the plant, but from there the voltage goes though 110 kV / 6.6 kV transformer to yet another 6.6 kV / 20 kV transformer to the common generator bus.
I have seen several smaller generator that have 6.9 kV nominal voltage, which is then send to 6.9 kV / 400 V or 6.9 kV / 20 kV transformer, depending of the distance to the load etc.
So, i'm quite sure that there isn't that many 150 kV generators, if any. Should be easier and safer to handle higher voltages at transformers that stay still, than in an enormous rotating thingy, that has super heated steam in the other end.
Yup, 99,999% of generators run on MV, up to 30-40kV. Thats basically the limit for synchronous generator
As long as you remember there's ”a rat” in separate you’re good..
Love your channel and all but I feel like you're giving out too much info to average Joe who's gonna think he's an electrician and burn a house down
If possible it would great to get one of these explaining fire alarm systems. And maybe cover WHY every fire alarm tech thinks they are rocket scientists compared to electricians. The amount of "I'm better than a stupid electrician" fantasy that these fire alarm guys have is asinine. They aren't that complicated and someone should expose that.
Dozofd
Wouldnt it just be easier to call this shit the same thing as everything else in the electrical system? Instead of primary side, just say line side and instead of secondary side just say load side...
Y y'all gotta make shit harder than necessary?
power distribution and the utility companies have different words because it's a different business with different codes to work under. (even though we know it's roughly the same thing) In automotive they call it "battery" instead of the line side. All of the loads are called by their circuit name. (radio, heater, wipers, etc) Again, a different business.