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- เผยแพร่เมื่อ 22 พ.ค. 2024
- This video will provide a brief description of the 3 Phase Synchronous Motor, and how you can lock the rotor into the same speed as the stator by placing a DC voltage to the rotor once it has established an rpm that is very near synchronous speed.
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Awesome demonstration Pete! At NASA GRC in Cleveland, we use many 10k+ HP synchronous motors to drive large air compressors. Although the motors are larger and the starting/running control systems are more complex, they work just as you demonstrate because the fundamentals are the same. Also, commissioning a system of synchronous condensors (spare synchronous motors really) is under consideration to help stabilize our grid. Nice shirt, btw. Thanks!
Best comment ever. Made my day. Thanks so much.
This is exactly the video I was looking for: demonstration of a REAL electrical machine, accompanied with very clear explanation. Thank you!!!
If only the motor lab at my school was this well set up, it'd be awesome! great vid :)
Great demonstration. Displaying the tachometer readings before and after applying DC current to the rotor would have made it perfect.
Great video that still applies. Perhaps the reason the motor didn't shudder in the beginning is there was no load? We did this experiment following a Festo/Lab Volt created lab, which asks us to start the motor at max load (3.0 N-m). Our set-up has the Dynamometer/Prime Mover module. We measured in excess of 3A winding current, and loud shuddering. Wish we would have known that was expected when first trying it!!
Excellent work professor. Exactly the same demonstration set up I had in college back in my engineering school days. Looking back now I only wish I had this video so I did not struggle as I did😂. I took many many iterations of reading and solving problems to get it and your video wrapped it all together almost 40 years later!
I have fond memories of learning about motors using the exact same lab-volt modules. It was a great system. The trade school I went to would start you on the modular trainers then if you were half decent at that you’d get to play with real equipment from the scrap pile.
Such a great video , I don't know where this channel was before. Thanks for all the effort
@9:24 oh noooo. And your story made me so proud for being so precise until then😉
That was awesome! My access with these stations is so limited that this instruction is perfect. Thanks. A lot!
This better than learning from my school :D Awesome!!!
Appreciate the effort you put to make me understand the concept sir.
I love your very clean and simplistic panels, and connectors for this demonstration.
Perfect demonstration , thanks !
Thank you this was very illustrative
Thank you very much teacher
God bless you
Thank you , that was very helpful 🙏
Excellent video; thanks!
Thank you for the excellent demonstration! I would appreciate it if you could illustrate the process of transitioning from induction to synchronous motor with an incremental increase in speed up to the synchronous speed. Additionally, if you could demonstrate the transition to a capacitive load motor with a fixed speed at synchronous speed through excitation, it would help me better understand the behavior in speed.
Thanks for the great video,
Thank you very much. very well explained
Thank you for a clear explanation....
Excellent explanation. Thank you. Any other videos like this one?
Great video. Thanks
Wow what a great explanation.
I can play all day long with that labvolt setup...
Hey thanks alot this help me to clear my concept
Hermoso, thanks very much! !
This is what I call education. Thank you for this video.
nice knowledge sir i full understand v curve and how it can be used for power factor correction (moter as a capacitor 😎)
thank you so much sir
this a great lesson . . .
Thank you sir for your video very informative 😚
this class rules! Peter is the best
Awesome my dream lab
thanks Mr .
The motor didn't shake as you expect it, because there is already a squirrel cage in the rotor which started the motor. It would do that only in a pure synchronous motor without the squirrel cage.
The other factor is the distance of the DC poles from the stator, the DC pole material, the number of turns, and connected load mass.
These factors do the following.
1 Further distance makes the motor primarily an induction motor on startup.
2 The pole material if solid and not laminated, will have higher shorted turn effect making it more an induction start. A laminated core is more difficult to start with DC applied at startup. Many of the motors have shorted rings of copper on the poles to reduce AC coupling while starting to prevent the high number of turns causing excessive AC voltage in the coil on startup. Examine the magnets carefully. You may find shorting copper rings on the poles, or under the winding is a copper sleeve making a shorted turn under or over the winding coil. I don't see it in this motor, it appears to use the squirrel cage winding for this.
3 The more turns the higher the inductance of the winding and the longer time is required to build current and magnetic pole strength, This auto delays starup pole field until after the motor has gained speed.
4 Unloaded motor with no inertial external load spools up faster. A large exhaust fan won't like starting that way.
Some small synchronous motors use permanent magnets instead of a DC coil. These often again have the magnets buried deep below the squirrel cage induction staring coils. These are often in small timer motors using single phase power with a shaded pole for starting torque, very low rotating mass for quick ramp to synchronous speed.
The comment that it would be pure synchronous without the squirrel cage is incorrect. It is synchronous when DC is applied. As there is no slip when locked, the squirrel cage provides zero torque at locked speed, so it is only a synchronous motor when locked. An induction motor at synchronous speed does so with 0 horsepower as there is no torque. An induction motor has torque when running below synchronous speed.
This was deep. Thx.
God Bless ya for your video :)
great info... do you have a "vars" meter kit to add to old synchronous motor drives to monitor the capacitance-resistance-inductance motor mode that things are OK? 🙂 thanks
Man!! What a vid!!! Really thank you!!!
Thanks so much for the nice comment.
Good lesson
tysm loved the vid! doing this lab at school
Nice. What school are you at?
@@PeteVree its called Qualitech its a trade school in QC Canada
It's worth noting in a real world setting, you would never EVER apply rotor voltage before the motor is already spinning. Some synchronous motors are made to be started from a dead stop in emergency situations, but generally speaking, those motors are only rated to do that two or three times in their lifetime. And they'll make a hell of a racket while they start.
Hey... we are using magnetic levitation bearings and brushless motors now. I thought we were way past using brushes? Why even have a DC motor to start it up when you can have permanent magnets in the rotor and use the stator to bring the rotor slowly up to operating speed beginning at 0 Hz and increasing it up to full operating speed. A microcontroller could look at the pole of the magnets and set the polarity of the stator windings to create an attracting force to begin rotating the rotor slowing and then staying just ahead of it as it accelerates to full speed. The DC motor portion seems to be a lazy engineer's way of getting around the problem of starting the Sync motor when the rotor is stationary and unnecessarily complicating its design.
@@JayDAnderson MG sets are still a thing. Also, what you're talking about requires the use of a specialized (and expensive) VFD setup. Also, you will never be able to yield the kind of torque results from a PMG motor that you can get from an excited field application. Also, a synchronous motor comes in another form: a generator. So, no. We are not past using brushes. It depends on the application.
Thanks, amazing video. May I ask you to set a video to explain with real examples the capability of the sync motor/generator?
Clean and thorough demonstration. I thought I've had it all together in my head... nope. :)
One question: what about the oscillation starting at 19:40? Did the motor as a generator hit just the right frequency?
Probably a mechanical frequency that resonated on the training unit
Thanks a lot! , I would like to ask, What happened with the VARs when I connect the synchronous motor on delta mode?. Great video.
If your input is a 208VAC a delta config results in 208VAC in every one of the phases (I don’t now if this configuration exists in our USA power system), therefore, 208VAC in each of the stators windings. Hence, a stronger magnetic field with all the resulting effects. It is a matter of looking at the motor specs to find out if it can handle these input conditions.
What happens to vars when motor is powering a rated torque load at full rotor excitement?
If I had a old Westinghouse synchronous motor with self excite could you make your meter run backwards. Just wondering if it works like that
Could the DC induction-motor component that is used to start the synchronous motor be omitted in the design? Since the frequency of the AC to the stator regulates the synchronous motor speed maybe it could be possible to omit the DC motor and Instead just bring up the AC frequency of the stator slowly up from 0 Hz to full operating speed? That way the stators' rotational magnetic field slowly pulls the rotor up to full sync speed (where rotor rpm = stator rotational magmatic field speed). The controller could keep the stator frequency increasing at a rate just ahead of the magnetic-hysteresis lag time of the rotor to bring it to full operating speed before any load is applied to the motor. Just to keeps things simple and not unnecessarily complicate things. Seems the DC motor portion just creates additional points of failure for the synchronous motor and limits the maximum speed and strength of the motor. It complicates dynamically balancing the rotor (cause there is DC motor windings inside it) and centrifugal forces could cause the DC motor windings to fail. Also, the DC motor keeps you from being able to use any permanent magnets in the rotor to improve the torque of the motor (additional assist to prevent a load from overcoming the critical-load angle and causing the motor to fail). Since the the synchronous motor stator is magnetically locked with the rotor this rotor could have some powerful permanent magnets in it to make it stronger except the DC motor starter prevents that improvement. The controller could just then determine which coil was closest to which magnet in the rotational direction of the rotor and give that stator coil an opposite (attracting) magnetic pole to get the rotor moving along. Since the rotor is magnetically locked when the motor reaches operational speed (is synchronized) it should be okay for the rotor sections to have permanent magnets to supplement the overall strength of the synchronized motor. The magnets could give the controller more time to respond to abrupt loads by increasing current to the stator before failure occurs. Just some thoughts.
This is was very helpful,thanks man .But I would like to know that why did the stator current went to 1A to almost zero when the motor was drawing 0 VArs (resistive load) and what were the terminal voltage of the stator when the motor was acting as a condensor.
The current goes to zero because the Over-Excited Rotor has generated a Leading Current that reduces the consumption from the Source (the motor is acting as a motor and a generator simultaneously. I believe the terminal voltage of the stator remained the same.
So the current remains the same? About an amp on the ac side and an amp on the DC side? Might as well have a larger DC rotor and stator with a gearbox to take over the transmission for a three phase AC Induction motor right? How much power loss would we expect to loose with modern frequency drives and drivers? I have drawings of capacitor driven DC motors around here some were. What if this shaft is pushing a vehicle that weights 1000 pounds?
Do well , much appreciate.
Is that why some motors, e.g. washer and dryer make a whirring noise as they spin up, then there's a click as if the motor is switching to synchronous mode?
Great demo, but why do some synchronous motors start and the same angle every time and other synchronous don't.
This is more of a conceptual question but If I were to couple this motor rotor to a shaft, and I try to lock the stator voltage first and then induce excitation on the rotor by increasing the DC power supply. How would this excitation reflect on the shaft ? I'm curious to know.
If the synchronous motor acts like an capacitive load, would it improve the cos phi ? and what would happen on other motors that are connected to the net ? Would the capacitive load improve the cos phi of those too ?
It would decrease the phase angle on the distribution system by providing Capacitive VARs to the inductive loads. Nothing visibly happens to the other motors connected to the Condenser distribution system. Here is a link for more info. en.wikipedia.org/wiki/Synchronous_condenser
Pete Vree thanks for the info. You're explaining it really clear! I've learned so much from your videos! Keep up the good work !
This phenomenon only occurs when over excited. See ‘v curves for synchronous wound rotor machines’.
@@PeteVree is there a way to use a synchronous motor alone to generate electricity for example connecting it to another motor like the one found in old cassette radios and use that as a source of winding energy but how would one deal with heat generated
What about the motors that have permanent magnets rotor? How do they start up
Is your watt meter showing real power only? Looks to me like its being effected slightly by the reactive power. Particularly when it shimmered.
The watt meter is set up to only display Watts, but this is black magic to me... no idea what is really going on behind the curtains.
Sir, Can we get a soft copy of this Lab?
Sorry if this is a dumb question, but I thought the rotor wouldn't turn unless you applied voltage to it. It looks like the rotor turns when you only apply voltage to the stator.
This trainer does rotate if voltage is only applied to the stator. The rotor has a squirrel cage component around the outside...the amortisseur windings.
We only apply DC voltage to the rotor once it is up and running close to synchronous speed
So the big advantage of synchronous motors is the ability to get reactive power close to zero?
what are the ball bearing looking things, also what is the variable on the motor plate
The bearings are probably wearing thin... we've been using these trainers for easily 15 years. The potentiometer on the front controls the amount of DC voltage applied to the rotor.
@@PeteVree cool i have been watching your lessons i wish i had one of those trainers to play with
I have a servo motor and want to know if it is a synchronous motor or a synchronous motor without turning it on(SGMGH-09DCA6F-OY
YASKWA ELECTRIC)
quick Google search says that this motor is a Servo motor: www.radwell.ca/en-CA/Buy/YASKAWA%20ELECTRIC/YASKAWA%20ELECTRIC/SGMGH-09DCA6F-OY/?redirect=true
👍👍
Do you sell this trainers
No, my friends at Festo Didactic sell them here: www.festo-didactic.com/ca-en/
Thanks Pete.
what will happen if rotor is exited with ac source did any one tried it in lab
Nothing good. The rotor would be the secondary of the rotating transformer and would induce a high voltage on the Primary. Our lab specifically states not to be a donkey and try this.
Dear sir very nice video but could you please send me the link of Synchronus generator experiment, i would appreciate as it will help our students alot thanks.
You can find a PDF of the lab on the following page: wyedelta.wixsite.com/html_canada-electrical/untitled-masterpage_63
Dear sir, I mean the video link if you have? I already have the experiment but want to share it with students.
And in fact i need video synchronous generator experiment. the one you share is motor.
@@waqarjanchd I have not done a video on that unit.
WHATSSS HAPPENING HOW MOTOR IS CAN BY CAPACITOR THATS SHOCKING THANK YOU GOD YOU SHOW MI THAT
What school is this at?
George Brown College, Toronto, Canada
You're not a Donkey Pete.
On the contrary, You're a Wise Owl.
angiesdiary.com/wp-content/uploads/2012/11/wise-old-owl1.jpg
Your experiment fails, because you are not able to energize your stator and your rotor independently you need another Breaker in parallel with the electric source. So you can apply the dc voltage to the rotor first and after a moment apply energy to the stator an like this is how you will demonstrate the vibration you are talking about because the rotor can not follow the speed of the rotating magnetic field.