What is Back EMF in DC Motor?
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- เผยแพร่เมื่อ 18 ก.พ. 2018
- This video tutorial explains how the back emf induces in the armature coil of the dc motor. In addition to this, you can find their advantages. Here, you will also come to know how back emf makes motor self-regulating.
You can further study this topic, on our official website:
circuitglobe.com/what-is-back...
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Beautifully explained the concept of back emf. Thank you very much for this beautiful video.
Clear and audible voice... Keep going... Congrats
Generally I don't like any TH-cam videos...but I like your video because your video is really very helpful regarding the significance of Back Emf in Dc Motor 🛵
The very best explanation, crystal clear 👍 looking forward to your next posting 🙏
It was amazing experience,I inspired just to watch your very first video,and waiting for the upcoming videos.
Great way to teach by clearing all sort of concepts that are mentioned in the topic.
Very well explained ...thank you
your tone is sweet, clear & continuous, if you take a pause then it will be little bit better to understand, if some more graphics or video, it will be better to understand. overall nice elaboration on back emf. Your control & knowledge of subject is fabulous.
Good explanation 😂😂 I love the way of explaining 💖
Superb way of teaching mam 👍👍👍👍
Very good explanation
Great explanation
Thanks for teaching me back emf. I have my exam tomorrow and it's been hard to study ever since dad started drinking again. Thank God your voice drowns out my mum's screams for help. Wish me luck for tomorrow.🤞
I hope it is not true
What is a dc motor? What is back emf?
Isn't it wonderful that when we flip a switch which is wired to a ceiling fan, the fan rotates! Take a moment to visualize the force which acts on the blades to keep them rotating while we are standing on the floor far below the fan. As if it is rotating by an unseen hand!
It operates based on the principle that a current-carrying conductor placed in a magnetic field experiences a force and this is what was encapsulated in the Lorentz force law.
A description of load torque always accompanies a discussion on motors. The effect of its imposition on motor torque, and how this causes the motor to draw power from the power supply then follows. The phenomenon of how it is the ‘back emf’ in motors, which regulates the motor torque to match load torque completes the discussion.
To understand these ideas, it would be instructive to understand Current, the conduction process and Voltage at the fundamental level.
Electrostatics and circuits belong to one science not two as in the following two videos:
i. th-cam.com/video/TTtt28b1dYo/w-d-xo.html and
ii. th-cam.com/video/8BQM_xw2Rfo/w-d-xo.html
The "back emf" or "motional emf" is a trick nature uses which has a regulating effect in determining the amount of current the motor draws and is a natural consequence of the induced emf process when a conductor moves in a magnetic field.
The fan pushes air and the molecules of air when they leave the blades produce a reaction force, a torque as the blades spin. The fan motor should generate sufficient torque to overcome this opposing “load” torque and keep the blades spinning.
The "back emf" regulates the current to generate this required torque automatically!
The governing relation for current in conductors is J = σE_net where σ is the conductivity of the conductors and E_net is the resultant of the applied and inducedcelectric field components in the conductor.
It is not possible in this post to discuss in more detail the process of production of the back emf and its regulating effect on motor torque.
The last frame References in video #1 lists textbooks 3 and 4 which discuss these topics in more detail using a unified approach and provide an intuitive understanding of the generation of an emf in generators and motors.
3 sentence in this video could gave me the answer I wanted..thankss
Superbly said
Mam your teaching method is sooo good but please use hindi some time plse
U r best teacher.realy sbd ni h apke lia kya khu bs ap bhut acha pdhate h.thanks
Excellent meadam use full for learning students good
nice video. very educating
Very good containt everything is explained
very nice friend, keep going
Tq mam.. Pls make video on speed control of dc motor
Thank you so much 🙏
Very well explained mam.make more videos
Superb. Cleared my doubts
back e.m.f is always opposite to applied voltage so it opposes not regulates otherwise system will become self operating and perpetual
Nice.... residential magnetism voltage...full video update plz
Thank you very much !! mam
very very good.from iran.
Thank you!
Nice explanation mam 👍🏻👍🏻
Explanation 👍🔥
Very nice explain
Nice explanation
Thank you
Nice teach 👍👍👍
Thank you mam
Fleming right hand is used in dc generator and left hand for motor
here right hand rule is used to find the direction of induced back emf
Thora pharle bhai abhi vhi time hei..
Fleming's left hand rule use in DC motor
But it accociated with Back Emf, not with motor operation. Back emf is motor generator acton during operation of motor.
fabulous explanation mam!! tysm 4 uploading such informative videos!!❤
Mam?? I'm pretty sure he's a guy
THANKS MAM
Owesom work
Hi...madam i have one dout! About
3phase motors. Are you clarify to my quastion?
For clarification; so Ia is the current supplied from Vt(Supply voltage)?
Awesome video mam fantastic
good explanation, iam new subscription 🤗
Very good
Best Indian accent yet
Impressed
Ur voice is so sweet
thnks
nice
Thanku madom
Thnq madam
Nice vedio
Nice g
Excellent explanation 👍
Super
Armature current depends which quantity mam
Today I have exam... tahnk you mam
''Go back to the basic equation for the force on a current carrying conductor is: F is proportional to BLI F=force B=flux density (the strength of the field that the conductor is in) L=length of the conductor I=current in the conductor This is an EQUALITY. If we invert it, we get: I is proportional to F/BL So if the wire is being pulled through a magnetic field, the current on the wire must increase to balance the forces. If it does not increase, then in a motor, the slip will increase and the motor slows down because not enough current is being delivered to the motor to operate at rated speed. In DC and synchronous motors, this isn't a problem because both rotor and stator currents will increase. In an induction motor, the armature current is coupled to the surrounding stator magnetic field. As load increases, the motor slips slightly more until the flux density and current in the armature balance out electromechanically at a new operating point which is a slightly slower speed. If you overload an AC motor beyond the pull-out torque, the motor stalls. The field is rotating at a constant speed, equal to 7200 divided by the number of poles in the motor windings. So a standard 4 pole motor has it's field windings rotating magnetically at 1800 RPM. When the motor is loaded to 100% of it's torque (horsepower) rating, it will run at the name plate rated speed which is usually 1-3% below maximum speed (usually about 1720-1750 RPM). As you reduce the load to 0 (nothing on the shaft), it will gradually increase to some place close to 1800 RPM but never exceed it. For most applications, this speed is close enough that most folks treat it as constant. OK, getting back to the original situation... In AC motors, the locked current (and also rated torque) is roughly 150-200% of the rated (FLA or HP) range. Since this is twice the motor's rated cooling capacity, and with an integral fan, there's no air movement, you can't normally operate at this point for very long. Once the motor starts coming up to speed, the rated torque of the motor actually increases even more (the pull in torque), until it gets to rated speed where the force, flux, and current all balance again. So at least for a short time (until the motor overheats), it can pull much higher torques. Once you stop it, you are limited to the locked rotor torque (150-200%), and the heat load shoots up very quickly since the motor isn't moving. So in your theoretical "gear box is shot" situation, you might be able to get it to turn over for just a few seconds before shutting down due to overload, or in some situations, it won't even rotate the slightest bit. Starting currents (as the magnetic fields suck down all the current necessary to charge the fields) is often 17 times rated current, and in energy efficient models has been measured as high as 21 times or more. Don't forget too that this translates into torque internally in the motor...starting currents are the most destructive on rotor bars, insulation, and anything else involved in generating magnetic fields. Even after this is over with, current during stall (locked rotor) conditions surges to roughly 6 times normal full load current. With this in mind, it's obvious why with across-the-line starting, "bumping" is very hard on motors without drives to control the torque/current. Assuming that you deal with all the other problems of using drives (heat loads, potential standing waves, and rotor current buildup), it should be obvious why motors driven by drives often last much longer especially in frequent start/stop conditions than motors driven by across-the-line starters. If you use a full vector drive, you can manipulate the operating point of the motor. You can change the rotating field speed (frequency) and voltage to allow the pull in torque to occur even at ZERO speed. This gives full vector controlled AC induction motors a higher torque rating (roughly double) than their DC brethren where on a DC motor, torque is fixed from 0 speed all the way to rated (base) speed. Effectively, you can operate a motor with fixed torque, fixed speed, or vary both, just as you can with DC motors. Again, this is of course within the limits of the bearings and cooling capacity of the motor. Adding an external fan cooling system makes almost anything possible. Unlike a DC motor, AC motor math is ugly because you have the inductive transfer of energy from the fields to the armature. Everything gets very nonlinear and it makes my head hurt trying to follow some of what the motor gurus are talking about. Just remember that the rated speed on an AC motor is "approximate", and that once you throw a drive into the mix, you can achieve a lot more with an induction motor.''
when we give DC supply to the DC motor force are created or each armature conductor.
what about AC supply
In case of AC supply same thing will happen, remember the supply voltage change on both stator and rotor so the resultant torque will act in same direction.
Rotor can rotate in anticlockwise direction . So its motor can not rotating in clockwise
Voice clear h
Motor runs according to Fleming's left hand rule.. :/
cheers babe
👍
Eb is inversely proportional to Armature conductor????
Mistake😝😝😝 arm current
i really want to see you bcoz of your beautiful voice
Flemming ka left hand rule hota hai
what is load?
Niggas liketeded her voice and accent though, that was the best part. Listening through a DragonFly Black DAC and UE-900 I.E.M.s and she sound cool, right like. Reminds your boy of Sravya his designated magnetism tutor with the sweet candy breath...
Starting music ka naam ?
Fleming left hand rule in dc motor
is this available in english??
This IS in english.
@@adhanda2017 you fooled me!
Fleming right hand rule in dc motor
I guess dc motor the cause is the supply voltage and to prevent this cause or oppose this cause the back emf develops and limits the incoming current ........but you have said the cause itself is the back emf.....
Supeb
Archana please understantlll in Hindi languge
actually ,Back emf reduce efficiency of motor
Now available bemf free motor
If the back emf high then need more current to maintain the speed of motor, back emf doesn't help to move motor forward..
I don't know why this back emf concept. Back emf is produced due to change in magnetic field due to rotation. Back emf is opposing the rotation not the supply (indirectly it is opposing).Correct me if I am wrong. I am fully confused☺
Rotation is due to supply voltage so the back emf opposes the supply voltage
I was here to study about back emf but your voice is too distracting.. #sweet😍
distracting yes, sweet no
yes. ..
Who's watching the shop?
Fleming left hand rule
Dear India Lady....backEMF...is.A.Great energy source....if.we.have RESONANCE....
Hey Bhagwan!!!......Flemming's left hand rule hoga.
Well energy conversion is not very well explained..
It could have been better
not right hand..it will be left hand
Fleming's left hand rule 🤦♂
Cause is supply voltage and not back emf
hiii
RIP Grammar
its left hand rule not right hand
U r beautiful ❤ u
you are just reading out and not explaining why does that happen.. especially in the 3 conditions of motor, you just read it out and didnot explain why those changes occur in no load or sudden load
You explain Hindi
Hindi ma bolo 🙄 pllay ne padraa🥺
Sahi baat hai
i didn't understand is it only me?
Who else loves "langes" law 😂😂
Not clear concept.. lots things left.
But over all ok.
Fak! Why every video i search about electricity has someone with a horrible accent talking??? So frustrating that i can't understand squad.
Wow seriously, don’t be an asshole. I can understand her fine and I’m English.
Fuck right off
That is because the U.S. educational system is so bad there aren't any competent english speaking persons to explain it !
Why are all these videos with Indian people? Did they just discover the Electric motor or somethinf