Will A Dimmer Switch or Transformer Control An Induction Motor's Speed: 038

Explaining and demonstrating how a dimmer switch, a Auto Transformer (Variac) and a VFD (Variable Frequency Drive) affect an induction Motor. This is a frequently requested video.
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Watch the Whole Series Here.
• Introduction To Motors...
If you want to chip in a few bucks to support more content like this, please visit my patreon page.
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My website www.jeremyfielding.com
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Technical Notes and Corrections
1. The VFD is a single phase to three phase VFD. It creates the other phases, and controls the speed.
2. Several people have left this video and immediately searched for a single phase VFD. I think they mistakenly thought I was saying this item doesn't exist. But the point was only that they are rare for a reason. They are only safe to use with a few special types of single phase induction motors without start windings that must be disconnected. The "rareness" of the motor makes the controller rare. They certainly exist, but you should not use them with the typical induction motor described in the video.
Resources used in this series
Video references
AC Motors
• AC MOTORS
Motor Basics (three phase)
• Video
AC Motors and Generators
• AC MOTORS AND GENERATORS
DC Motors and Generators
• DC MOTORS AND GENERATORS
Brushless DC Motors and Brushed DC Motors Explained
• Brushless DC Motors an...
What is Ground
• What is Ground? Earth ...
What is electricity
• Video
How to read a schematic
rimstar.org/science_electronic...
• How to Read a Schematic
Websites
www.studyelectrical.com/2016/0...
www.leeson.com/TechnicalInform...
www.johnsonelectric.com/en/res...
motors/principle-of-operation
rimstar.org/science_electronic...
www.usmotors.com/TechDocs/Elec...
Induction motor as a Generator
www.usmotors.com/TechDocs/ProF...
Books
Single -Phase Motor series number 723 by Edward Amrein
Not on amazon.
Amazon affiliate links
DC Theory by NJATC
amzn.to/2vMRwDn
AC Theory (get the used one, don’t spend $100) by NJATC
amzn.to/2wjgaNA
Three Phase Motors Series number 724 by Edward Amrein
amzn.to/2fUo217
Innova Multimeter 3320
amzn.to/2x0wQ9T
Tachometer RPM gauge
amzn.to/2x35Bv6

[@victorbingo3205]

I have been studying this sort of thing for a few years, and I have watched other engineering and machining channels. I learned more in 5 minutes of your channel than ALL of the other channels in YEARS! You are a gifted teacher, thank you Jeremy.

[@JeremyFieldingSr]

+Victor Bingo thank you!

[@mcorrade]

same here. I thought I knew what I was doing but learned more from his videos that any other source before

[@victorbingo3205]

mcorrade it's like he filled in all the blanks I had.

[@MrPatdeeee]

Amen, Amen and AMEN! This man KNOWS how to turn a high tech subject to a "piece of cake". Any technical school would be a fool not to hire this man YESTERDAY. He is a treasure for sure. May Jesus continue to gift him with knowledge that can be taught easily to the masses.

[@slumahkhamis3052]

Victor Bingo q@zzzxxxssx Is r600tq Ki

[@dmoore3722]

This channel is so underrated!

[@JeremyFieldingSr]

+D Moore tell some friends!

[@RajbirSingh-wg9pf]

I agree.

[@shanecapps9601]

Dude is amazing

[@RUS38]

Agreed!

[@CR-xl7zu]

Thank you, Jeremy. You saved me hours of research looking for a product that doesn't exist.

[@stuffbywoody5497]

Brilliant. Instead of just saying "this won't work", you have actually shown us it won't work and you have explained why. Much appreciated.

[@malcolmhodgson7540]

Jeremy, May I add to the applause given by so many others. I have been trawling the internet for knowledge on AC motors and their control and operation, 10 minutes with you has been a revelation! I also watched some of your other videos. You are a great tutor. Thank you. You deserve more recognition.

[@MaturePatriot]

Love your videos. They have taught me more about motors than I thought I would ever understand.

[@alansexton7]

Just extremely excellent stuff! A+. You have a powerful gift for teaching.

[@1999Valkyrie]

Jeremy, this is possibly the finest, best demonstrated video I've seen on the subject of "Is it possible to change a motor's speed with a dimmer switch, etc." I give you a hearty two thumbs up!!

[@Robinson-Homestead]

Jeremy thanks for all your help great video.

[@marcushoward2527]

Thank you for all you do here brother, you’re an amazing engineer and a gifted teacher. It’s my opinion that for many of us fortunate enough to possess “the gift” of “innate understanding” we often times forget to appreciate this skill and remember to use it to help others find what some are gifted with. It’s not always easy to do for the “hyper analytical”, and technical mind. So I thank you for reminding me it should always be shared, I salute you sir, you win at life man. 07

[@cuttheloop]

Wow, I would never have imagined this would be the result. Thanks for putting this together.

[@sobertillnoon]

Jeremy, I can't tell you how much I enjoy your videos and how awesome I think you are. All I can do is thank you for the content. Thank you very much.

[@klausnielsen1537]

I find this very helpful and entertaining! Between you, AVE and Great Scott i am always entertained and learning new ideas. TY ;-)

[@JeremyFieldingSr]

+Klaus Nielsen you bet. Thank you for letting me know :)

[@RayMAKES]

Another great video Jeremy!

[@DoctorShrink]

Always high quality tuition on this channel. Perfect combo of essential detail, logical sequencing and hits the most common misconceptions most people have. When people really know an area they can distill the essence. Well done.

[@nazirsoogun5014]

Thks Jeremy ..you make complicated issues look so simple and hats off for all your simple and clear explanations and solutions

[@pathikpatel3373]

Thanks, man! Sometimes you find EXACTLY what you were searching for on KZbin and for me, this is one of those moments. Your video saved me a LOT of time, headache and money. Keep up the great work 👍

[@eljeffo2871]

Wow, never even though about the starter capacitor kicking back in at lower speeds. Thanks!

[@thomastorretto2772]

Simple, straight forward explanations. I love your style. Thanks!

[@kens6169]

Very good information. I was looking at ways to lower my drill motor speed and you’ve cleared up a lot of questions.

[@mcorrade]

U DA MAN!! Thanks Jeremy that really clears up all my misunderstanding about speed control, VFD and induction motors. I now realize ALL my issues and what I can and cannot do. These edu vids are greatly appreciated

[@TheGuitologist]

Excellent video.

[@keithfoxlow-nm2nk]

Thank you Jeremy for sharing your knowledge in such a simple but very effective manner. I learned all I needed to know in such a short period. Keep up this great work.

[@artemisrumbinger4012]

Mr. Fielding thanks for another awesome video. You have an effective way of explaining the what's and why's of things.

[@jimhester2004]

Fascinating. It answers some questions I've though about, and you explained it in a very effective way. Thanks.

[@evil17]

Great vids Jeremy. Just one comment I would like to make is, it would be great to see the volts and amps ( and possibly even Hz and rpm also) in real time in some of these videos as well for added perspective of what is actually happening in the circuits. Love your stuff, keep it up, very educational.

[@JeremyFieldingSr]

👍

[@RickaramaTrama-lc1ys]

I was highly impressed to say the least. You make learning this type of thing fun and I appreciate all your work compiling the stuff you need for a great video.

[@ASTMA325]

Your videos are outstanding. Thank you for taking the time to make them!

[@simonbabnik2331]

Very informative, right on the spot.

[@literoadie3502]

It's important to note that when you slow the motor down you also lose power. The torque on the rotor is determined by the strength of the magnetic field acting on it, which pretty much stays constant, leading to a loss of power (same torque at slower speed=less power). This is a problem for machine tools since you want constant power throughout the speed range (for example a drill press, lathe, milling machine etc.), meaning torque needs to increase (NOT stay constant!) as speed decreases to keep the available power more or less the same. Work done by a particular cutting tool moving past the material at X speed and at Y depth of cut is the same regardless of radius of action (small drill vs large, small milling cutter vs large, small diameter work piece in lathe vs a large one etc), therefore if the RPM is dropping (to keep the tangential speed constant), torque needs to increase for a constant force behind the cutting edge. Power is Force X distance/time, so constant force at the tool requires more torque as the radius of action increases (and constant tangential speed require less RPM as radius increases). The only real solution is a mechanical reduction, i.e gears and pulleys, which multiplies torque proportionally as the speed decreases, keeping the power constant (more or less, ignoring some mechanical losses). Or, sufficiently oversize the motor that you still have enough power at the slowest speed you will be running it, but that's obviously not as efficient, and not nice to the motor. There is NO magic solution, embrace mechanical reduction whenever you have it, even when you have a 3-phase motor with a VFD, so you can keep the motor running as close to its rated speed as possible, for maximum available power and a cool running motor (the motor fan also slows=less air flow!). I would love to build an external reduction gearbox/pulley system for my future lathe, to achieve very slow speeds at full power and have more speeds in between the stock speeds (be it a geared head lathe or a belt drive). I'm not a fan of slowing motors down at all, although a VFD with a big 3 phase motor would be nice for soft starts, quick stops, and moderate speed control between the different gear/pulley speeds.

[@gregmorgan7610]

I learned more in 10 minutes than i did in two hours of googling. Subscribed. .

[@gianfrancofronzi8368]

You explain the process that you went through to get the results that you did. That's why your videos are so good for the common person. You don't just tell us what to do, you show how you reached each point of the process. Thanks Jeremy and keep up the good work.

[@grantnm1]

Jeremy, This is one of your best videos. Thanks to you, I have a better understanding of motors. I have a question I hope you may be able to answer. My wife and I bought a vacuum cleaner when we were in Japan, and as you may or may not know, it has ~100 -110 VAC, 50 Hz coming in to the inlets. If I plug the vacuum cleaner in a 120 VAC, 60 Hz inlet, the vacuum may work a short time but turn off. At first I thought it was a fuse or something blown, but then I thought, plug it into a step-down transform... It worked. The vacuum cleaner says that it will work on 100 VAC, 50/60 Hz. The average volt when I checked it when we were there was 110 VAC and the vacuum worked. Any thoughts on what maybe going on? Thanks!

[@JeremyFieldingSr]

I am not sure. I would not expect 10 volts to make a difference. How much did you have to lower the voltage? Also, does it seem to be getting hot?

[@grantnm1]

I was thinking the same thing, because it only about a 10%, give or take. I just took the volts reading from the incoming, 122 VAC, Step-down output 105 VAC (13.9344% difference). I will crack that thing open and see what's going on. I am also thinking there maybe a current or voltage limiting circuit inside. Thanks.

[@dysan45]

4 years late I know but may have to do with the frequency. I've been looking into an imported compressor being sold here in Barbados on special, turns out it's on sale because the 2hp single phase motor was intended to run on 115v 60hz, however the motor gets hot on our system which is 115v 50hz. For most 60hz appliances with motors or compressors e.g refrigerators, washing machines, treadmills, AC unit, etc, we usually use a transformer to step the voltage down 115v to 105v, most common is the 1000VA version. It's referred to locally as a stabilizing transformer but doesn't seem anymore different from what is online labeled as step-down, autotransformer or voltage reducing transformers. I never gave the need for them a second thought until the compressor sale. My research for something powerful enough or other options like inverters etc led me to understand that lowering or raising the voltage affects the Volts/Hz ratio. Google it for a better understanding of how a few volts less affecs frequency, speed and cooling, torque etc

[@heldercabral1309]

Hello! Thanks a lot for the great tutorial. My question is: Whats inside a variable speed power tool? Cant be that big of course.

[@BYENZER]

Great Q!

[@aldenhauser9555]

Well they don’t use brushless induction motors. They use brushless dc motors (which uses pwm to control speed) and brushed dc motors (which uses voltage to control speed). Those are much easier and very compact speed controllers to manufacture

[@KAL00KI]

Watching this video saved me a great deal of time in my endless search for a single phase vfd controller. Thanks

[@PsRohrbaugh]

You have an amazing blend of theoretical and hands-on knowledge. I've seen people who are good at one, but being good at both is rare and impressive!

[@1MoGuzzi]

Top Notch. Thanks.

[@johnheidmann1616]

Thank you for your excellent presentations. I have a 30 year old Thermador vr600 kitchen exhaust fan with a single phase 120 volt induction motor. It seized up and was able to repair it by lubricating the mounting bushings, no bearings. There was no capacitor and the motor turns on with a 360 degree rotary switch that graduates from high to continuously lower speeds without electronic speed control. Variable speed and no capacitor, how is this possible.

[@timr86868]

it's a universal motor, not an induction motor.

[@brave_ulysses5958]

Excellent video. Thank you for the time and effort to make and post it!

[@deepakbhaskaran7299]

I really appreciate how you explain these things. Great job Jeremy!

[@DonJKrasniak]

Great video! You answered several questions, even the one I had about my dad's old router speed controller. SO, I am interested in slowing down motors like found in a shop fan... like the bigger ones (18" or 20" metal blade like the one that stands on the floor or pedestal) which seem to have speeds of fast, faster, and fastest, but all are too fast because they are noisy and move way more air than I need - but these fans are durable and can't be replaced with a house box fan or oscillating fan. What can I do to slow them down? IDK whether the motors are 3 phase or not in those and I'm trying to avoid disassembling mine which is still working after 15 yrs+.

[@d.e.b.b5788]

I'm in the same situation. I've been asking people about this for years, and have yet to get an answer. Yes, it's like producing a mini tornado going through my house, or no air movement at all.

[@VideobyHomeworks]

Man, you're smarter than a whole treefull of owls!👍😎 Good job!

[@richardhenry371]

What kind of owls?

[@llaporte1615]

Exactly what I was looking for. I learned a lot. I was thinking of trying the same router controller. Thanks for highlighting the warnings.

[@davedennis6042]

You are doing what you should be. Teaching is your genre because you are good at it. Very thorough and informative. Thanks.

[@tengelgeer]

Although you indeed can't dim an induction motor it does sound like it's not even starving the motor because the triac isn't turning off. Because the lacking of current with an inductive load it's hard to turn off a triac. So I think if you place a bulb parallel to the motor while using the dimmer it will not dim either because the triac isn't turning off :D

[@JeremyFieldingSr]

+tengelgeer now that sounds like an interesting experiment. I will try it and let you know what happens.

[@mariopuzo4509]

I used to think I was somewhat smart.

[@nickmbuguas]

Thank you Jeremy for the clear information on how to reduced speed of motors. I have been having to sort out this issue for a month and now I know what can work and what won't.

[@kellyvcraig]

As grownups go, you are pure gold. Thanks once again.

[@joelangdon7359]

Your video was very informative and your presentation is the best video I have ever seen on youtube. Keep up the good work.

[@NuManXplore]

Very helpful video, answered my questions about this subject very well! Thanks!!

[@baltsosser]

I had a conversation this week over this very topic when a friend and I were looking at a single speed electric motor. I wanted to do something external to the motor to change the speed quickly, perfect for a lathe. You reinforced exactly what he said, so we will go another way. thank you for the great presentation.

[@-dazz-]

What an awesome channel, thank you Mr. Fielding. You have a new subscriber here from across the pond.

[@1chamoy20006]

Every video I learn so much!!! I’m getting all the concepts down.

[@peterparsons7141]

You make really good videos. I like the way you explain the function of electrical devices, and different way to utilize them !

[@skinostra]

Top video,excellent explanation in plain english.I have been looking for a single phase VFD but no one makes them probably for the reason you stated here.Keep up the great work,I am now a subscriber.

[@eyuptony]

I'm no electrician, your easy to follow explanations on this subject are brilliant.

[@cecilandrews1875]

This videos has to be the most clearly explain speed control for an induction motor I have seen yet.

[@1969Kakashi]

Subscribed. I wanted to know what to do with the giant stack of variable transformers I have. Now I know I can't use them for speed controllers on induction motors. Very well explained, Jeremy. This is KZbin gold.

[@frankieb64]

Great way to convey confusing information. Your explanation makes so much sense! Thank you!

[@mattsfat73]

I had to sign in to comment ... major effort there on my behalf :) BUT that was a very informative video, much respect from AU.

[@ngenes1]

Jeremy you are the current day Tony Stark lab workings. Your videos have taken the guessing game out of a complex working motor and enabled others to quickly understand . Thanks for your help.

[@richardebbage686]

Thanks for that Jeremy - You have explained why my Myford lathe has belts and pulleys. Cheers.

[@Leo99929]

Within seconds I realised you are a smart cookie who actually knows what you're talking about. That's rare on KZbin. I didn't need to see another video, insta-subscribed!

[@Halfrican4111]

Im surprised you're not more popular. Very informative, clearly articulated without an overwhelming personal thirst for being flashy. I barely comment nor subscribe but I found you so informative that I had to credit your efforts.

[@JeremyFieldingSr]

Thank you so much I am honored

[@jeffbeck6501]

You have the best basic motor education videos I have seen. This video is about the most ask question ever and few explanations about this subject on youtube. And for whatever reason, there are few basic motor education videos in a real setting using real stuff that you would really find for cheap or free. This is a great video series you have about motors. Thanks.

[@JeremyFieldingSr]

Thank you

[@accidentaltradesman5139]

I’m sitting here trying to figure how the speed control on a fan motor works and I’ve been racking my brain on it a triac style speed control would work!!! I’m so glad to have found your channel!

[@jefflong9890]

So I'm building a lathe and I wanted to control the speed. Having experience with DC steppers and achy servos I understood some basics. A friend was asking if he could use a 1/3 how motor and a fan switch. This video was the best way to explain that you can't. I pointed him in the direction of a nema stepper and a driver/ breakout board. Thanks for your video very helpful!

[@foxboro1204]

I've googled this topic for quite sometime and have a faint idea about it. 5 minute watching your video made it so much clearer, especially on why i cant find single phase VFD 😅

[@davidsutton2996]

I as well have been doing research on this for a belt sander. Thank you for the knowledge my man.

[@michaelsimpson9779]

Thank you for your excellent content. Clear, concise and very thoroughly explained. Again, thank you.

[@derekgewecke2419]

I've spent countless hours reading, looking at diagrams and formulas only to feel like I grasped a tiny portion and still not completely understanding why certain things work and don't. You have taught me more in 20 minutes than I've learned in hours of reading. That router speed controller in the exact one I was trying and left confused why it wouldn't work. Thank you. Keep up the good work.

[@jamesmccoll4211]

Amazing, so helpful. A really good video and you are a great teacher and explainer.

[@rhajmand1933]

FINALLY an understandable explanation for why I can't dial down my grinder (induction) motor speed. Nice job!

[@zsoltszekelyjewellery8216]

Hey man! As they say it's not enough to have it taught. One's gotta be able take in the teaching!. And you mastered it. To the point that you can teach it now.. You got skills to convey the message at hand! Nicely done!

[@DWORLD-xl4pb]

YOU JUST SAVED ME $28. WORTH THE PRICE OF VIEWING YOUR VIDEO...AND DONE WITHOUT BEING LADEN WITH COMMERCIALS. BRAVO! AWESOME! 👌💪🏽✅👀

[@shvideo1]

Excellent topic and very well presented. Thank you very much for sharing your knowledge and doing it so well.

[@robertevans6481]

Another great video Jeremy. I need to save this one for future reference....

[@colinwarner7762]

mate you know your onions, this item has helped me no end, thank you very much for your time and effort. regards cousin, Colin UK.

[@gilbus4989]

You just answered my question. Thanks. I knew your knowledge would give me a proper answer.

[@javac08642]

Thank you Jeremy so much for explaining this I've been trying to figure this out because I am building a metal lathe and I want to be able to control the speed without using a belt system or gears.

[@murraychadwick9362]

Thank you so much. Your videos are always very educational and answer my questions 👍

[@gottchanumber5387]

Best diy video ive seen in a while. Thanks

[@terrystevens8890]

Thanks for the awesome explanation. I wondered why I couldn’t vary the speed of a motor I have, and. Now I understand. Glad we have intelligent people like you on here .❤️🤠

[@Rev22-21]

Excellent demo. Motors were never my strong suit. I appreciate this. It tells me something about those variable speed drill motors now & them being a brush type design.

[@TheXscorpius]

Sir...Every project you make, you teach us, more and more. Keep on educating us, your student. 👍🏻👍🏻 :) Thank you.

[@JeremyFieldingSr]

Thank you!

[@MarkMcCluney]

Excellent vid as always Jez, thanks for sharing mate.

[@timfowler4642]

I very much like your explanation of this stuff. You make it easier to understand. Thanks.

[@JeremyFieldingSr]

Thank you!

[@nckbck]

excellent video. practical for industrial applications. thank you for making this!

[@corollagl82]

You saved me a lot of money by showing what to avoid. Many thanks.

[@ekdromoi]

thanks man. I've been looking for an answer to this and going through it in my head for a while. feels great to finally have an answer

[@JeremyFieldingSr]

👍🏽

[@siddharthabasu5607]

Most practical illustration. Thanks.

[@tomcarranza810]

Once again another very informative video! Thanks Jeremy!

[@gasinstallerallgasinstalle7953]

Clearly explained, so easy to understand when someone knows exactly what they are talking about! Hope this guy's a teacher in university, if not he should be! Thanks for the education.

[@DESLA-Waretown]

Excellent video!! Was trying to adapt a single phase motor to make a knife grinder. Now I will use a series of step pulleys. Much easier and cheaper to build.

[@dwight19463]

I really enjoy your channel. I just like to learn about different ideas. You are very knowledgeable and interesting to learn from.

[@aitf99]

I've been trying to find a way to slow down a bench grinder. Thanks for confirming my findings. No other way other than 3 phase and a VFD... Great video.

[@hemp1958]

Your knowledge is very well delivered. Looking for more. Thank you

[@danspowercleanservices6060]

Best explanation I have ever heard. Thank you!

[@williamwixon]

Thank you so much! Electricity has always been a mystery to me even when it’s been explained! This video really presented the material in a way that I could comprehend. It’s really amazing fascinating and cool thank you so much! That was really cool to watch you turn down the voltage on the induction motor and have it run at the same speed! Now I can understand why they would burn out if there was a load applied to it! 👍💯👏💪

[@markreed2643]

gifted teacher ..keep em coming ...everyone loves your flavor on these subjects ....what ever it is you have it .... thanks M from down under Australia 240v