Fun Fact: Water and electricity DO mix! But only if it is ultra pure. Large power stations circulate super pure water inside the conductors used inside the generator motor windings to keep them cool. The generator windings are large 3" thick copper bars formed into windings with a hollow core for the water to circulate inside. (Re: 10 years as a trainer at a twin 1150MW power plant.)
Indeed while "water and electricity don't mix" is pretty decent advice for general application, pure water is actually a pretty good insulator. The problem is many things like to dissolve in water (like salts) and those ions or even just particles floating around will make the solution conductive. In fact, a common way of measuring water purity is with its conductive-ness. Typical antifreezes will probably have additives that would probably make it more conducive and of course water will corrode various metals in a transformer thus becoming conductive and just causing damage from the corrosion. And out on all that the relatively narrow working temperature of water is also problematic. Anyways, there are lots of reasons why oil is preferred in these low maintenance systems, although water is actually a better coolant than oil.
I'm not sure why it matters, the resistance of water is enough that unless it's strongly electrolytic, it works well for cooling as accepts heat well. Typically, though, water cooling is best for indirect exchange and oil for direct exchange of heat, due to the potential for the water to become electrolytic through contamination or electrolysis caused by the remaining impurities giving off oxides.
Electricity isn’t conducive in distilled water The only reason water is bad to mix , electricity is because of the minerals and that help conduct electricity.
Nicely done. 👍 for anyone wondering ONAN is a naturally cooled by air transformer and ONAF is air forced cooling by a fan and usually having find to radiate heat out away from the transformer core.
I can remember back in the mid 1960's going to our local "City Dump" w/my Dad to drop off some junk from clesning out our garage. There was one of those transformers laying on it's side in a pile of brush and other crap. All the concern over PCBs came later.
My son was a first year apprentice lineman The back feeding of a improperly installed back up generator is exactly what happened to the Journeyman/trainer he was working with he was severely injured my son had to rescue and bring him down sadly he didn’t survive
@@davidd1395 Yup. And if it's not generators, it could very well be induction from other energized lines, or even faulty UPSs that don't disconnect from their line side when they switch to inverter power.
We've had 3 transformers blow in our neighbourhood in the past 5 years. Pretty spectacular when they go. Blows the entire top of the pole off and starts it on fire
These days, those little power supplies are not using transformers. They are switch-mode power supplies. They take anything from 90-240vac and using switch-mode technology make almost any voltage you need. From 3.3-50vdc and the output is regulated and over-voltage and over-current protected. I use a lot of them in my projects. I have a Masters Degree in Electrical Engineering. And I’m enjoying your channel very much! Thank you!!
@@micsky99 Yes that’s true. But they are typically high frequency. So, a 10 amp switch mode power supply internal transformer is “tiny” compared to a 10 amp 50 or 60 hertz transformer. And some switch mode power supplies don’t use a transformer at all. Some small power supplies only use a fractional coil on a powdered balun. These are charge pump type, like an Apple charger for example, and during the pump cycle, a mos-fet will charge up the coil, then when off, the stored charge will keep a capacitor charged. Again, these run at about 600KHz to around 1.2 MHz, and are called ‘buck’ converters. I have a 40 amp 5vcd switching power supply, and it does use a small transformer, but it’s tiny, and weighs almost nothing. Another reason most passenger aircraft use 440Hz. The transformers and motors are smaller and lightweight compared to 50/60 Hz transformers. Thanks for making that correction. Appreciated!
@BigDaddy_MRI : I have a propensity for digression but will endeavor to stay on course for the sake of brevity. Retired now but when I was doing control work on production machinery I had to install small XFMR ( Step Down 240/120 PRI -Sec 24 Volt A.C. this XFMR had a feature called " FOLD BACK " . In other words you could load the secondary side to it's rated maximum, but if the secondary was shorted it would actually draw less current shorted than when fully loaded. Any idea how this was accomplished ? I had 4 yrs. theory as a journeyman wireman, NOT on an Engineering level so I can handle some basic theory if the answer requires it. But if the answer requires a visit to some guru in a Himalayan cave quoting Napier Logarithms, calculus and 3Rd Harmonics, I will respectfully withdraw the question. Working with an engineer on a generator one night, I found a wire disconnected. I asked.." Bob, how do we write down what the problem was, a loose wire ? His reply " no not a loose wire " " there was a failure to maintain contact integrity of that wire " Engineering eloquence at it's finest !!
I am a retired electrical engineer whose hobby is building high voltage equipment such as Tesla coils, Marx generators, Cockroft-Walton multipliers and pulsed power generators. I just wanted to let your viewers know that we high voltage hobbyists sometimes use pole transformers as step-up transformers which is of coarse the opposite of the way that they are intended to be used, however the transformer doesn't care if its being used as step-up or step-down. I use a 10 KVA 14.4 KV pole transformer as a power supply for my large spark gap Tesla coil. It puts out 9-foot long discharges with 6.5 KVA of input power. Its always a big hit during Halloween with several hundred spectators.
During a large storm, I heard a large crack type explosion. I knew immediately the transformer got hit by lightning. The entire area was blacked out for a day. It was really close, like less than 200' away.
Very cool video! I use to work in substation, now I'm in generation but anyways, we would clean our insulators with water from the power plant across the street. The substation can not be shut down because of customer demand on it. Until that day I thought for sure water and electricity do not mix. Turns out, they can but the water is not the danger, it's the minerals and contaminats in the water that conducts the electricity. So, very weird feeling washing insulators on an energized tranformer and breakers. Demineralized water or demin water is 100% safe to use for this process. Corn cobs that have been crushed to a fine media also is an excellent cleaner of porcelain insulators in an energized environment. Just be very aware of approach distances because they don't change and you can be killed quick.
Wall warts of yore were pretty much just a transformer. Nowadays, although they contain small transformers, most of the interior parts are other electronics to regulate the output and to run the transformer at a higher frequency than 60Hz so a smaller transformer can be used.
I am wondering when/if ever we will use switching power supplies in place of the big, heavy transformers we have now? Probably would help with heat and efficiency.
I'd say probably not considering the added complexity and electronics of a SMPS which would likely be more susceptible to voltage spikes from lightning and heat (at least the semiconductor parts), not to mention it'd be converting the high voltage AC, to DC, and then back to Pure Sine Wave AC at that which requires a fairly complex inverter and lots of filtering. And finally there's really not much of a reason to replace the 'big heavy transformers' considering they're not really using up space that would otherwise be used by something else, as they are transformers are super simple, reliable and robust.
I met a guy working for a company that did Oil Testing on Transformers. He informed me they often pop the lids open on live transformers to take samples. He also said that's also when most new hires quit too LOL.
@@billybob042665 Actually the day I met this gentleman he had to take the lids off because the transformers had no valve or plug. The substation was de-energized because it was DuPont's policy of no access while hot because the transformers were pole top units set on concrete pads on the ground. Which means the conductors were at chest level. So yeah I can't actually say he's done it live before but on that particular day the cans did have no valves or plugs
A switch mode power supply is not always a transformer. Some do have high frequency transformers and/or an inductor (which is basically half a transformer) in them, but not all.
A SMPS taking power from mains will nearly always include a flyback transformer nowadays. A power MOSFET is used to switch at high frequency on the primary side of course. If you are aware of any product plugged on mains that doesn't include a transformer (of any kind), I would be very interested. And even lower voltage DC/DC converters will need an inductor for buck/boost topologies and friends. The only case I can think of with truly no inductive components are some DC regulators like LDOs but I bet you some transformer stands between that and mains. And a LDO is not a power supply nor it is a switch.
In Tesla coiling, we call these pole pigs! Back feeding is a good way to kill linemen and generators! For Tesla coils, we have to run with a ballast on the 240V side to limit the current. I run with a 14.4/7.2 KV 10KVA pig with arrester.
A direct lightening strike on a transformer can create a brilliant light show as well. Happened at a business I worked for. They had multiple transformers mounted on a platform that was mounted above ground between four poles. They provided power to several buildings including one that used three phase motors. Several of the transformers blew open sending flaming oil way up in the air. Southwester Public Service Company did a tremendous job getting new transformers put into place and repairing other damage. Fortunately business was slow at that time but they got everything fixed and running in about eight hours.
Hi. My dad worked for the power company a long time ago. He worked there for like 30 years as a field engineer. I wanted to become a lineman sooo bad but they would not hire family. Politics. Anyway I wish I was. I have a strong knowledge of electricity and wish I could have done it so its interesting to follow you.
5:54 is just a GFCI mounted on the end of a power lead for a hairdryer, isn't it? Not an actual transformer, because hairdryers run on 120VAC don't they?
Many of the so called transformers for modern electronics are actually switch mode power supplies. They do still contain transformers, but very small due to the high frequencies used in such power supplies, unlike the "wall warts" of old.
@@TomStorey96 he wasn't talking about any of the smps. He was talking about the GFCI at the end of the hairdryer cord. It's not a transformer, it's just a GFCI. 110V in and 110V out.
A few years ago, I was minding my own business at home when I heard a loud boom. I looked out the window to see a blazing inferno. The transformer on my property (bout 20 ft from my house) blew up violently. The flaming oil caught a portion of my lawn on fire, which they later dug up and hauled away. It was a perfectly calm summer night. Must have been a ticking time bomb.
had no idea there was oil in them, makes me wonder about some of the extremely rusted transformers i've seen out in the countryside, those are probably going to leak at somepoint.
They very well could! Dead grass at the butt of the pole is a good sign of a slow leak. The transformer will soon fail if too much oil is lost, but any unit that's showing extreme signs of age/rust should be looked at.
I used to work with a 1950s tube type X ray defraction machine at the university. The back had about a 100 gallon tank of I assume PCB oil with breadbox sized insulators glowing white hot. It had a 10 digit display on the front of counter tubes which were fascinating. It was like Lost in Space. I never felt safe around that thing.
For some reason we lose at least one transformer a year in my town of 3000 people and 9 out of 10 times it's one of 3 that are right outside my house. It was really loud the last time it happened a couple months ago. We are usually the ones that end up letting them know which one went. We also seem to loose our main transformer every couple years, talk about loud and bright.
Does the current on the high voltage side return to the substation transformer through the earth via that connection from the other end of the high voltage coil to the ground?
Older ones contain pcb oil which is harmful in the sense that long term exposure will cause cancer which is why they have been replacing those with newer ones in the event of a spill, it wont be as hazardous to the environment.
I just wanted to say thank you for all the information you are presenting. Real world stuff that you can't find anywhere else. Books and Internet searches always give such dumbed down generic theory with no specifics.
I built these for a few years. We wrapped ours in copper, they last longer. The ones wrapped in aluminum ( like in this video) couldn’t take the heat and burned up quicker. Aluminum ones were cheaper, you get what you pay for.
We have one in our back yard (yeah, in my town they run utility wires on poles through peoples back yards!) and even with the slightest wind or thunder storm it trips and the few of us in the neighborhood on said transformer are SOL for 24 hours until they come with a long extension pole and reset something on the top of it and our power is restored. This has happened 3 times in the last month - it's getting expensive!
If they at working specifically at the pole with the transformer...They're changing the fuse on the cutout and closing it back in, unless there's a little "csp" switch on the transformer. Very well could be animals getting into the wire that feeds the primary bushing. It may be worth inquiring if there are any animal guards installed on the bushing and wire feeding the transformer. (If there isn't, there should be). The same type of fuse would also be protecting the main feeding the back lot area.
The power adapters around the house are not actually dry transformers these days they are mostly switch mode power supplies, they do have a small ferrite transformer inside thou but, they do not run directly at line frequency like distribution transformers do. They are not called dry transformers as such they are referred to as switch mode power supplies. In the 80's most power adapters were actually little EI dry single phase transformers, they were rather heavy. A switch mode power supply or SMPS is vastly more complex than a dry transformer, and tend to go pop more often so you have to keep replacing them for new, too boost manufacture profits. While the iron core transformer is simple, its the most clever and most efficient machine ever made.
Not sure what brought me here, think it was a tangent from fixing a charger. Thanks for sharing, as an EE (industrial electronics) found it interesting.
Hey Dre! It could be a dual voltage transformer, or may be a step up transformer feeding into a 24.9KV system. Looking at the size of the insulators or bushings can help in identifying voltage ratings... However the proper and only real acceptable practice is to check the nameplate!
An easy winding design is the “center tapped” transformer. Halfway through the winding of the secondary a connection is made and then you have half voltage x 2. This is what home distribution transformers do. The center tap is the neutral, each leg is 110 v and across full winding 220v
There's a pole transformer a couple blocks from me, as I drive by I can see it's completely rusted on the outside, I figure just a matter of time before oil leaks out and it overheats and starts burning which will catch the trees beneath it on fire. Apparently no body gives a hoot about it🤷
As a lay person, I'd guess 90% of the time or more it's because of lightning damage, which can take a while to degrade to the point of failure. The rest could be an installation problem or undersized for load problem.
Good video. I am wondering why they used to build transformers with PCB's inside. In my area of Ma, we have been at war with General Electric as they used to dump PCB into the local river, this river leads to the Hudson which is now also polluted with PCB's. This dumping has made a mess of our local river and G&E has only stepped up a bit. Again very interesting. Thanks
The old oil is basically made of PCBs. PCBs are good electrical insulators and don't break down easily with time or heat, which is basically the issue.
Not once, but twice have I seen lighting hit a transformer just 10 feet away from me. Luckily both times I was in a car. They caught fire. Lots of black smoke.
Is energized solar that does not go down during a power outage really that dangerous for a lineman? It seems to me that no living lineman would ever work on a high voltage power line, grid down or not, without treating it as though it were live? Or at the very least testing it for power before touching it? I am also certain that like everything that I know almost nothing about that it is much more complicated than what I know :)
The inverters made for grid tied solar incorporate a technique called "anti-islanding" to prevent such an occurrence. If the grid goes down your panels are automatically disconnected. You won't have power either. Standard procedures for linemen working on a branch of the grid call for opening the fuse(s) feeding that branch, marking the pole or box where those fuses are located so that another crew doesn't reconnect them inadvertantly, and shorting all the high voltage phases on that branch to each other and ground.
@@doneden5368 My solar panel system disconnects from the grid and keeps producing power. If the lines are tied to ground what is all the talk about "protecting the linemen" about then? In theory the inverters that did not disconnect from the grid and kept trying to produce power would be damaged when the high voltage phases were connected to ground?
The one i saw blow up was the transformer. That shit literally shot oil all over the place but i rember the oil was alot darker than that im assuming its mineral oil?
You didn't show the windings. I want to hear you dumb down 3p w/delta high leg. Had a guy who spent 20yrs teaching at IBEW and couldn't do it so students could understand.
Another great video! I have a basic understanding of 3 phase AC power since that was a requirement of my job. I also knew about the oil cooling used in x-formers. What I'd like to know is how you (seem to) use a single tap off of the primaries to deliver 3 phase AC. What sort of witchcraft is this? I promise not to tell. Cheers
@@gerardmoran9560 To provide 3-phase power you’d need 3 transformers. I don’t know if any manufacturers package 3 of them together in a single can, but my guess would be no.
As mentioned elsewhere, these are not there phase transformers. (Although, 2 or 3 of them could be used to transform 3 phase.) To answer your question: The can itself is the other leg of the primary. The can is grounded and so the "neutral" primary wire is grounded, too. Also, the neutral on the secondary side (the center tap) is also connected to the can and also grounded.
The transformer that feeds my meter hums and vibrates in the winter. You can hear a pulsating hum through the wall behind the meter in the house. I even touched the pole and you can feel it vibrating. It is the last pole on the line at the end of the road. Any ideas what causes this? Is it safe? I called the electric company and they told me I'm just hearing things. Everyone who has been here in the winter can hear it and I have recorded the humming as well. But they still don't believe me. Any suggestions?
Dino: If you magnetize steel, it will change dimension slightly (the term is magnetostriction). Also, if some of the laminations in the transformer are not tightly clamped/welded together, they will vibrate. In either case, the frequency of the vibration/sound is twice the frequency of the electricity supply (i.e., in North America, with a 60 hertz supply, the vibration/noise is 120 cycles per second; in Europe, a 50 Hz supply yields 100 Hz hum). "Better" quality transformers will be quieter, but cost more. Most of the time, the vibration and/or noise are "only" nuisances.
Very interesting video, thanks. I have a question which may have nothing to do with electrical power but I’ll ask anyway in case it is. I’ve also seen someone else ask it but he didn’t get a clear answer: Once in a while in my area I pass some metal pots attached to the top of sticks on the side of the road. The pots - which looks like typical pressure cookers - are about 1/4 mile from one another and attached to the tops of the sticks around waist-high. I have not seen any cables protruding from the pots. I’ve always wondered what they were for. Does anyone here know what I’m referring to?
The cans that look like pressure cookers are telco T1 repeaters. A T1 is a 1.544 Mbps digital circuit often carrying 24 multiplexed phone or digital circuits. The repeaters reclock and amplify the signals. There are cables going into the bottom of the cans.
I'm not sure, that's a really good question! Quebec, Canada had a large CME related outage back in 89'. It's quite an interesting subject. I'll definitely have to read up on it
@@Bobsdecline If you can find out, do.... You see, there's a lot of tension in the world right now, if an adversary detonated a nuclear devise above us in the stratosfear it would create a mega EMP, If the entire country lost power, everything would grind to an immediate halt, many people would die, be a hero.... Help me figure it out.
It depends on the density of electric consumers in the area. In the US it isn’t uncommon to see one wire single phase (no neutral conductor) in older farming communities. The issue is that it causes some residual voltage in the area around the ground, which might be fine with one house every few miles. But if you do this in dense areas you are going to energize a whole lot of the ground, pretty dangerous to walk near. Also a poorly installed ground rod can be deadly
In virtually any circumstance that electricity encounters water unintentionally, it's not distilled. Therefore to say water and electricity don't mix can be an accurate statement. Distilled water and electricity in a controlled environment would not conduct (depending on the voltage) Frozen water also acts as a pretty good insulator.
