Buck-Boost Transformer

Explanation of how Buck-Boost Transformers work.

[@ecvolt2976]

I’ve watched almost all your videos I’ve been a master electrician for 40 years and a electrical inspector for about 20. I owned my own electrical company for years. And taught my men both Electrical theory and Code. I can say without a doubt I have never seen anybody have a better grasp on electrical theory and principles along with an understanding of the national electrical code as you. you are doing a great service to the young men and women who are trying to learn the trade. I want to thank you for being such a great teacher and helping others support themselves in life

[@aaronshults8472]

I love the eye contact with hand gestures. Truly feels like I'm sitting in the classroom watching your lecture. You don't rush anything. You give time to think and let intuition set in. Like I said before you are a treasure.

[@markmark2080]

I've hooked up a few Buck-Boost transformers over the decades and simply followed instructions resulting in success...Now I understand what I was doing...MUCH obliged.

[@steveyoung8560]

Dave, Dude you are now my favorite transformer teacher. I learned so much from this video, please dont stop.

[@Greg_Chase]

Just perfect stuff. I taught STEM topics at UC Santa Cruz and because everyone got ratings from students at the end of each course - lecturers like me were compelled to make the content ACCESSIBLE to as broad a range of student preparation as possible. The unpredictability of students' preparation to absorb the material forced lecturers to work hard at clarity. Your presentation style is EXACTLY what students need. The explanation is paced perfectly - not too slow. Not rushed. The diagrams are perfect. The logic of the different circuit windings is made so clear, it's impossible to fail to understand your explanations. Nice job! Thank you.

[@davidd1395]

We in the utility business call a buck/boost transformer a voltage regulator. Awesome how they work to maintain a preset voltage automatically. Your videos are awesome for basic understandings.

[@richardschneider9837]

Excellent description of buck-boost..thanks.

[@jesseord4206]

I'm currently taking my fourth year and these videos you've made are so incredibly helpful for me to remember all the things I've forgotten since I was last in school! Thank you!

[@jordanpatrick6050]

Very well done on this explination!

[@Hohmies86]

Love your style! Thank you!

[@manuelcuellar1738]

Thanks, the best transformer teacher

[@eugenelong1134]

Just stumbled across your videos. They are great, and informative. They have reinforced what I learned in electrical school.

[@kevinhale628]

Awesome videos. Thorough and to the point. thank you

[@michaelcostello6991]

Excellent lesson. Amazing stuff. Thanks

[@nathanrice1796]

Good clear explanation. I'm glad I ran across this video.

[@srisha8]

Simply fantastic explanation!!! Thanks a lot Sir.

[@kgt9535]

Awesome illustration, my brother. Great parallel you drew between that DC circuit and your AC ones.

[@edfeten4724]

I just found this channel, and I love it!!!

[@musicandsoundtracks4024]

What a great teacher.

[@garbo8962]

I went to a great VO Tech high school for that taught us so much. Still after over 50 years can remember being told on all three phase loads to use three buck boost transformers instead of two due to better voltage regulation but nobody seems to mention this. Probably 90% of the buck boost transformers that I did install was on 120/208 panel where a machine needed 240 volts. Years ago I called up a great big used transformer & motor shop to see if they could supply me with a 480 to 575 volt buck boost arrangenent. They sold me used small and maybe three times larger transformers to boost the voltage up to 575 volts. It was on a 500 ton injection molding machine with around a 75 HP motor. Found easiest way to splice the thick secondary wires on buck boost transformers is to use a short nipple and mount them right above at least a 4" trough.

[@Sparky-ww5re]

A buck boost works great for 600 volt motors that more than likely were Canadian imports into the USA, because 347/600 volts is exclusively used in Canada, but is rather uncommon in the US, but 277/480 is not used in Canada. Also some older industrial facilities, say from the 40s and 50s, ran 600 volt ungrounded or corner grounded delta three phase to their large motors.

[@insylem]

I build industrial control panels. Most of out stuff is 3 phase 480. We had a customer in Canada need 3 phase 575

[@SHarris64]

I’m a 30 year journeyman in Canada and I have worked on a lot of 575 volt stuff, but I also built and designed equipment for a passenger train and all that equipment is 480 as it needs to operate through North America. I’ve been lucky to work on some very cool stuff over the years. 🙂

[@82hochol]

Thank you for great videos!!!

[@motionsick]

Brooooo. Thanks! Hooking up a 230 machine to 208. Kinda know what I'm doing but this verified everything in the transformer manual.

[@danielrunov4800]

Thank you so much for your videos!

[@Cyprusdoctor]

Dave ,you are a very good Instructor!Peter.

[@nooone86]

Just amazing

[@mattwebb8234]

Great analogy with the battery

[@geoffreydavis3367]

good explanation, thankyou. im installing one today. its a 120/240 16/32 1ph 1kva emerson

[@victorco.6308]

Very clear explanation

[@24electricservice]

Very well explained.

[@itsourlife]

Good video. Thanks👍

[@aubreyroche5080]

Outstanding !!

[@hemiolabooks450]

Zen like clarity, love it.

[@mmh1922]

Well done!

[@BlackMamba-io8zr]

I'll never forget now how buck boost transformer works😁

[@mikebavoso26]

Good job of explaining

[@Mikael5732]

Thank you. I learned.

[@russellviper4769]

thanks foe nice explanation

[@tonystephens9743]

God bless you sir

[@t3jkelectricos601]

gracias muchas gracias

[@imtheonevanhalen1557]

Finally....an explanation for simple minds!!!

[@bobparrott8130]

😃👍 Very good

[@jimlibby699]

Can you do a class on the sine wave of using single phase from 3 phase and how two legs 120 apart can be used in place of normal single phase 180 apart. And inversely how we go from 180 to 120 via phase converter.

[@Call-me-James]

Thank you for the nice clear explanation. I have one question: Can anyone tell me how to interpret the manufacturer power ratings of the transformers? Is it the power rating of the overall circuit, or just the power rating of the low voltage secondary?

[@Satchmoeddie]

I could have a huge jobsite where I am using miles of extension cords and a boatload of voltage drop, so we would boost 120 volts up to 136 volt. We also had a gigantic tugger that came with miles of SO cable and it had a pair of buck boosts mounted right on the side of the frame. It liked to see 240 volts, not 208 volts, or sometimes less than 200 volts.

[@davegordon6819]

I know I'm late getting to review some comments, but it seems as though you are seeing it correctly. It's good that the tugger came with its own Buck-Boosts because most job sites these days will not have the 240 V available. You've got a double whammy and it wouldn't take long to burn up the motor if you tried to run it on 208 V that is suffering voltage drop because of long cable length and higher than rated amp draw due to under voltage to the motor.

[@Satchmoeddie]

@@davegordon6819 One of the cheesy residential apartment wiring doper roper outfits ran boost transformers to accommodate their literal miles of cheap orange SJ extension cords they used for powering the large heavy duty Milwaukee Hole Hawg drill motors. Without the boost XFRs they were burning up a lot of drills. We'd sometimes add a full 32 volts to 120. Most reputable companies would use twist lock capped #6, #4 or even # 2 AWG SO cable & spider outlet boxes. Some of them might run a second temp line to the farthest reaches and still boost it by 12 or 16 or even 24 volts. Our SO temp wiring snakes were 3 wire + ground single phase 120/240 into feed thru spiders. That wire tugger had a small 3 speed automotive gear box on it with a powered reverse gear & 3 forward gears. They are juts awesome old workhorse monsters~! They are made for pulling wire UP high rise building conduits & chases. NEVER try to pull wire down in any high rises or on other tall structures. Gravity is NOT your friend! It will run away on you and you will have jacks, spindles, & spools half full of cable all flying towards the conduit. OSHA will fine you too, if you survive. They guys at the bottom will have a mile of 500MCM or larger spewing all over the place. You KNOW what's going to happen, but some people have just gotta see it for themselves. I have had to tell a few companies, "F you, see ya later. You wanna kill people that's fine, but I am going to go live, job, or no job."

[@robertmaddox1441]

Buck-Boost, well presented, Please include how to rate the kVA rating of the Buck-Boost Tranformers

[@psionl0]

A more efficient wiring arrangement would see all of the windings in phase. Connect H2 to H3, H4 to X1 and X2 to X3. Connect the input across H1 and X4 and the output across H1 and H4. Of course the output voltage would be 240 x 240/272 = 211.8 volts but that is still within 5% of 208 volts (1.81% to be precise).

[@johnbelt7676]

Came here looking for this. You’re correct for a buck. Both of his explanations are boosts with a misunderstanding about the direction. I

[@psionl0]

@@johnbelt7676 Buck transformers are commonly shown miswired like this - even by professionals. Simple maths will show that if all the windings are in phase then the transformer can handle greater power. His method of wiring a buck transformer is similar to how we would wind a non-inductive resistor.

[@johnbelt7676]

@@psionl0 I’m replying here because I just hooked one up this way switching just the low side “polarity” exactly like the video and both “directions” produced a boosted voltage. So I removed one of the line poles and connected it to the other end of the c series coils and my load to the center point of the high and low coils and it worked perfectly to buck. I think there is a misconception here with how an auto transformer configuration would be similar to a dc circuit.

[@psionl0]

@@johnbelt7676 I think I would need to see a diagram to understand what you are saying here.

[@craigthorner256]

THIS GUY IS GREAT. I just went to school about the operating theory of the buck boost transformer i am about to install on my inverter heat pump which blew up its main board that is rated on the AC supply at 208-230VAC and where my FPL power from the utility is typically 247 and has gone up to 262. Now at least i fully understand what it is doing in wiring diagram I. By the way i am working with an Acme Electric T113074. The only thing that yet troubles me is that the wire coming into the AC supply south of the AC fuse box (60A fuses) where the AC is rated at 50A max (typically 20A or even less due to 1/3HP scroll compressor motor), well the wires are 8 gauge or so, and the wires in the buck boost appear to be only 12 gauge, which say they are good for 20A and not 50A. Anybody know why the buck boost that is correctly specd out and purchased for 50A max are so thin? Also, what is the best way to connect fat low gauge wire, 8 or 10 gauge, to 12 or 14 gauge wire? Should i solder or use wire nuts? I don't necessary expect a reply to my post so in the meantime let me thnak Dave Gorodn for a great video!!!

[@SHarris64]

Odd question, I’m assuming any multi-winding transformer can be used as a Buck/boost transformer, but are there transformers specifically built as Buck/boost transformers? Or is that more a description of how the transformer is being utilized? Thanks!! Great video! 😃👍🏻

[@Mr.Catnip_Pawbreakers]

Just made me think about clockwise vs counterclockwise windings....which I assume is the controlling factor in the arrows?

[@xandriasmall6668]

could you do a video on using buck boost transformers in a 3 phase system, how transformer rating relates to usable power and what kinds of currents i can expect to see on each line and load. i'm looking at purchasing 2 or 3 3kva 32v secondary transformers to boost my 208 to something closer to 240 in an open delta or wye config. I'm considering bringing this into a breaker panel and just labeling it 240 single and 3 phase only.

[@bobcocampo]

Please discuss line to ground voltage for ungrounded system single phase and 3 phase

[@michelsuykerbuyk2078]

Thanks for the very clear explanation!! Still wondering though: As the grid voltage here is sometimes a bit high (255V+), now and than the solar inverter stops because of this high grid voltage. Do you think it's OK to put a buck transformer between grid (connected to primary) and inverter (connected to secondary), AND exporting still OK without any harm to transformer,...? Thought about primary around 240V, secondary around 15V.

[@davegordon6819]

No, I would not suggest that as a solution. If your voltage from the power company is that high I would call them and see what they have to say. That seems a little too high for normal... implies there could be a problem somewhere.

[@joenewman763]

My question is how do you size a buck boost transformer to a load like say I have a 208 volt system and a 240 volt 60 amp instant water heater

[@82hochol]

What if boost 1ph 120/208v to 1ph 120/240v ? Is Boost transformer working or go with normal dry type transformer ? L1 to ground is 120v & L2 to ground is higher than 120v?

[@DanSchallerforPOTUS]

Current doesn't leave the positive terminal, it leaves the negative terminal.

[@Joshualbm]

I have a friend who hears a tone in his house, like a hum from a transformer. It oscillates irregularly between 72 and 144Hz. The utility company's come by and couldn't figure it out. Disconnecting the main doesn't help either. It's very faint but seems to set up louder in some portions of he house, like a standing wave. All the utility transformers are pole mounted as well. I wondered if it my be some underground pumping or Diesel generator somewhere. But the frequency and level is always the same. Would 72Hz show up as a vibrational frequency in US power distribution or through interactions with motors in 3 phase operation? It's a really baffling phenomena.

[@user-mz6ur9re5j]

👍👍👍🌹🌹🌹

[@danielfosco8426]

Midterm practical tomorrow 3phase to a load to a buckboost

[@eyalvolkmar6558]

For some reason, the wiring from the buck boost manufacturers like Jefferson and Federal Pacific is different. Jefferson diagram 4 Federal pacific diagram D

[@hugorangel3902]

I should mention that I have a neutral on the primary

[@jayo-motter-pops]

So the input (B phase) is hooked up in parallel with the H1 and the line to the load on the 240v equipment?

[@davegordon6819]

If you're referring to my comments in minutes 5:10 - 5:30, I'm saying that in that case I wouldn't be using the transformer as a Buck-Boost transformer, meaning that I wouldn't be bucking (decreasing) or boosting (increasing) my initial voltage. It would be like running two loads in parallel with each other - the voltage is the same for both. If my source is 240 V and my load needs 240 V then no transformer is needed. Just run the wires from the source to the load. To sum up, the source wires energize the primary windings, and to get a buck or a boost one of the source wires needs to then go through the secondaries for the adjustment to take place.

[@hugorangel3902]

Hello, what if I need a buck and boost to go from 208v on the primary to 240v with a neutral on the secondary? Thanks in advance.

[@bobbrumley3964]

Just ground one phase and now it’s called a neutral. The difference between phase to phase and phase to neutral is simply ground one phase.

[@davegordon6819]

I know I'm long in getting to this question, but after a long Covid time I'm finally getting some free time. Hopefully someone else can benefit if you already found your answers. If by "neutral on the secondary" you mean you want two "hots" and a neutral (like a house service) then here is an explanation I gave someone else. I also included a few comments on three-phase because you didn't mention what type of system you're working with. SINGLE-PHASE: If we use a single Buck-Boost transformer to achieve a desired output of 240 V single-phase we would need to use any two phase wires (A&B, B&C, or C&A) for a 208 V single-phase input voltage. We would have a 120 V potential between either of the two phase wires and the neutral (the neutral point is by definition, a center point of a system - see NEC definitions). In this "boosting" scenario we take one of the phase wires and, after connecting it to the primary winding, take it out to the load (this wire will maintain its 120 difference of potential with the neutral). But, the the other phase wire that connects to the primary winding needs to then go through the secondary windings so the difference between the two phase wires will be "boosted" 32 volts to achieve our desired 240 V difference of potential (this is what I casually refer to as the "manipulated/adjusted/boosted" wire). It is this second phase wire which gets its voltage "shifted" in relation to the original neutral. The main objective here is that we get a 240 V potential between two wires and this has been achieved. If the load in question needs a neutral then this is not the tool for the job. (I can imagine a set up of two Buck-Boosts similar to the open-delta arrangement of the three-phase systems where one could use a neutral in place of the middle phase to achieve a three-wire single-phase 120/240 output. You could probably get voltages that are close enough to what you desire, but I don't recall any manufactures showing such a schematic under the "Single-Phase" heading. This, my friends, is a common problem in our trade. Just because we can get a desired outcome, it doesn't mean that the equipment is listed (or even intended) for that use, nor does it mean that it is acceptable to our code rules... It does mean that we are thinking about how things work which is admirable; we may just not be aware of the safety issues that could arise...) THREE-PHASE: For three-phase I recommend you do a web search for "three-phase buck-boost instructions" and you will generally see in their literature the diagrams for single and three-phase installations. It is possible to maintain a "centered" neutral when using three Buck-Boost transformers (one for each phase), but you will need to follow their diagram closely (not all instructions show this, but look at Eaton's). It is also restricted to "Wye" systems only. What happens here is that each phase is either increased (boosted) or decreased (bucked) relative to the neutral and so it maintains its "center point" definition.

[@waynehuman1554]

Good Day Dave. I'm a New Bloke/Guy, on the Block, and Only have Basic Electronics Experience. I can only Entertain the Complements of Those Whom Praise Your Lectures. Our Government can't do the Job, And Epic Sums of State Coffers Revenue, has Vanished. Our Internet work Sometimes, Without Subtitles, Due to three to Four Electricity Breakdowns Dayly. Desperately Need to do Two, 12 Volt DC to 220 Volt AC Inverters, 2K5 to 3K Watt Rating. We run 220 Volts Mains, Over Here. I can Get Bits And Pieces of Transformers, That uses the so Called, Number 4 Core Area Size. Is it Perhaps Possible for You to do a Video on One of These? Regards. Wayne. Johannesburg. South Africa.

[@shamanking5195]

what is the difference between step up , step down and buck - boost transformer ???

[@davegordon6819]

A "step-up" transformer is used to step up the voltage meaning that the output voltage is higher than the input voltage. Similarly, a "step-down" transformer is used to step down the voltage meaning that the output voltage is lower than the input voltage. "Buck-Boost" transformers are versatile in that they can be used to either step-up or step-down the voltage as needed, but only in a range of about 5-30% of input voltage. "Regular" transformers can be ordered for any voltage configuration, often changing the voltage by large percentages or multiples of input. A major advantage of using "Buck-Boost" transformers is that they are small in size for the same load relative to a "regular" (or isolation) transformer. This is because the "Buck-Boost" is only transforming part of the voltage (the increase or decrease amount).

[@davidperets9997]

this guy play with voltages like kid with lego

[@zizitopp]

Dave Gordon are you a JATC local 46 instructor?

[@davegordon6819]

I was for a few years, but not currently. If you're in the area and interested in the electrical trade it is a good place to apply to get into a union apprenticeship. You could also look at Local 77 for outside line work. If you're in another area look up the local IBEW/NECA training facility (normally called a JATC).

[@robertpearson8546]

Are you going to define a buck-boost resistor and a buck-boost capacitor? A transformer is a transformer. The physics does not change when the surrounding circuit changes. Maybe you should scrap the 1920 buck-boost circuit and look at 2011 circuits.

[@johnbelt7676]

This is not the correct way a buck works. The general idea is correct but the connection are wrong. The “relative polarity” is an effective illustrative concept but not a factor for this system. For a buck, you do not connect both lines to the high side coils, just one. The other line is connected at the other end of the needed high and low coils connected to each other in series (individually the high or low side may be connected in parallel or series as explained). A better way of thinking about a buck is to think about how coil voltage taps work. You have a defined could length and depending on how many turns into the coil you tap for voltage your voltage will be reduced or increased.

[@jeffgreen7897]

Be quiet read the instructions on the transformer you get and wire it so you get the voltage you desire. Everybody’s got to be a critic.

[@johnbelt7676]

@@jeffgreen7897 it’s important to know what is being taught is not correct and 4 out of five jmen that haven’t installed a buck can’t decipher the diagram because it’s NOTHING like a regular transformer; it’s an auto transformer connection.

[@jpw643]

This is a terrible way to wire this.

[@davislyerly9811]

Explain then, makes sense to the rest of us