I am an Electrician/ Instrumentation Specialist/ PLC Programmer and I have been working with vfd's for years. And have encountered many of these issues. But I have never had it explained to me so eloquently. Thank you, you have made me smarter......

Your the best electrical teacher I’ve ever seen. Thank you very much from Dallas Texas!

I work for a shop building control panels for exactly the application you described here: VFDs running ventilation fans. We recently built an order of panels that contained huge line reactors. I never understood exactly what they were doing until I found this video. Thanks so much!

As an Electrical Design Engineer for motor systems, this is the best video I have seen on this topic. Your delivery method was on point ; clear explanations without over complicating things.

Please for the love of God keep posting. I get many careless instructors who shouldn't even be teaching. You're such a great help to us all, I've got my whole class into these videos!

Amazing explanation. One million of thanks

You are a great teacher and I wish you were my teacher.

In 11 minutes you explained my whole semester ....very bad college teacher I had...plus I have to pay for an awful teacher that did not know right from left...Thanks!!...you are making a positive impact for all the electrical trade and design engineers ...

thank you Dave, very clearly explanation as always...

Hi, Dave! I'm a motor engineer and regularly work with a VFD. This is a fantastic explanation of function of a VFD and I had to share it with my coworkers. Keep up the fantastic work!

You make things easier... Thank youuuuuuu

Best explanation on KZfaq, as well as your other vids. Please do not stop making them.

Awesome videos

I love your explanations. Thank you sir!

Years ago we had major issues, fractional horsepower motors driven by VFD's with very long runs. Killed several motors until we installed output reactors . Reflective wave !

I think I might finally have found the best channel teaching these concepts. Clear, concise, practical oriented (as opposed to overly abstracted, unfortunately too common usually in physics teaching) and simply put. Already knew this but needed some clarifications that you provided in a short amount of time, which is greatly appreciated ! Subscribed. Thank you sir.

I came here on a search for info about saturable reactors, but I stayed here for the lesson.

I never thought a subject like this could be taught with little to no math, but this is outstanding, clear and intuitive! Great job, Mr Dave.

Retired from a very large hospital/research center that had over 500 VFD'S from 2 to 1,750 HP. Most had line reactors .. Newer drives had fancy reactors that were in panels with 1 or 2 contractors and capacitors. One boss always insisted that we ring out & megger line reactors while troubleshooting drives. Think I might have checked two because good ball was standing there. We had a great drive tech who only worked on drives for over 20 years and asked him if he ever came across a bad or open line reactor. Told me nope and they are bullet proof. In a new 12 story building all motors 60 HP & larger had 18 pulse drives at pit out line reactors . Luckily all but cooling tower drives were within 75' of motor and used common building wire between drive & motor ( THHN/THWN ). nice vid.

Carrier frequency, harmonics.....lots to learn

Very nice sir

Awesome explanation

Great stuff !

You make things look so easy, Great?

Fantastic explanation. Very clear and helpful.

Great video!

Common mode current will be induced into the rotor of an induction motor, this current has to go back to the neutral of the source, this path is usually goes through the bearings causing damage and a short life. Use a ground brush on motors above 150hp😀

This is good explanation

Great video Dave! thanks for your effort.

Simply Awesome...!!

smellss quality here! keep doing it!!!!!!!

Thanks!

Hi Dave, thank you so much for the comprehensive explanations. Allow me to ask a silly question; whether the isolation transformer blocks harmonic current generates from the VFD? Thanks 🙏

Hi. Good vid. I have a question about a reactor and the use of it. Lets say after the power grid, in normal installation (here in Norway 400V, 50Hz TN-C-S 3 phase). Where I may have som issues about short circuit currents (above 60-70kA). Is it normal in the US, or other parts of the world using a reactor to lower the max short circuit current infront the main panel board for instance? It accured to me when I searched around on the internett and found your video. You see, I am a installer (not a word for it in english as I know about. But it is in northern europe a person qualified to have the certificates and government passed exams after education to make DOC's for electrical installations). I am responsable of design and build electrical installations as the "installer" in my company. Anyway, I have to lower some short circuit currents. In most cases this isnt a big problem to solve with coordination of the breakers to make them have cascade (backup) functions to eachother. But in this case, we are so close to the transformer, so I cannot really make this right now. It might help if I have the voltage increase by over 7.5% from the transformer when short circuiting. But that means I have to change transformers as well. Might be hard to understand, but worth a shot.

Yes

I like how you explain things and I have a question. I have a 3phase 380V AC servo spindle + driver but have only 240V single phase AC. I see two options to get 3 phase 380V. One is to use an inverter 240VAC to 3PH 380V and drive the inverter output to a line reactor and feed it into the servo spindle driver. The other option is to use an inverter 240VAC to 3PH 240V and drive a 3PH autotransformer where I get the 3PH 380V. The 240VAC to 3PH240V inverters are half the price of the 380V inverter. Which solution would you recommend? Didn't mention the inverters I have are 10KW (I have both already) and the spindle servo motor is 3.7KW but it has a load factor of 200%

I don't know if my question could be appropriate, but let me ask you: I never had the opportunity to make some measurements. When some running capacitor is lower (microfarad) than the specified, I know that a motor can still be running, but the question is: can it use more energy to run? and, in case of start capacitor, e.g., can it compromise the life of a compressor, if the capacitor is below the minimum specified?

I don't know if I'm wrong, but wouldn't a saturable reactor be good for filtering on a VFD? I know at lower frequencies it would be impractical, but I imagine it could be somewhat helpful, even if clunky. I could be wrong though, and the load current might not even need to be filtered at all.

Can you explain how VFDs can have 2 lines and 3 loads? (single phase in and 3 phase out)

🎯

You could do it so much simpler by just having a 2 coil and 1capacitor and pulsing it at certain frequencies so that it gos at certain speed.

Sir iam not able to run an inverter ac on a 5kva sine wave inverter. Inverter transformer is vibrating even at 900 watts and the PF was 83. I had tested resistive load of more than 2000 watts on this inverter. is there anything to do with harmonics, since its an inverter ac which has vfd like thing? also kindly provide the solution. Thanks..

Wow…

Please write video Hindi explanation

IGBT