Very good explanation and demonstration for power factor correction. It is always nice to see demonstrated with actual equipment instead of just on paper.
We recently bought an LG fridge, and there is an iPhone app that allows us to monitor the fridge electricity usage and cost. I checked the current usage and multiplied it by 120V, but the result didn't match what the iPhone app reports. It was actually higher. It turns out I overlooked the power factor (PF), which in this case is 0.73 or 73%. This led me to wonder how we could make the fridge more energy-efficient. I haven't taken any action on that front yet, and I'm not sure if I ever will, but I was curious about what value of a capacitor would be needed to correct the power factor. And then, I found Serge's video that answered all of my questions. I want to express my gratitude to Serge for explaining everything so beautifully! The CZcams University.
This is a well articulated video, very rich and informative in its presentation.Added more insight to my understanding of the topic.Sir, please keep up the good work.Great thanks.
Great set of videos Mr. Levesque. What a valuable resource for electricians in training. Some minor points because of my HVAC background. 1. That capacitor the guy at the HVAC store sold you is a "start" capacitor and will burn out in a few minutes if you use it for "run" duty as you have wired it. 2. We have to be careful in distinguishing between motor efficiency and power factor. They are NOT the same thing. 3. I don't know about Canada, but in the residential USA billing, the meters bill you by KW and not KVA. Although it is always good to have near unity power factor, the fact is that for an existing installation any improvement in PF benefits the Utility more than it does the homeowner. Unless of course if they have a low PF penalty, like in commercial billing rates. Keep the good stuff coming. Best wishes.
To clarify point 3 above a little more: If your T.I.P is 333W as you correctly compute in your video, then you are only paying for 333/120 = 2.7 Amps. This is because the utility meter is reading KWh and NOT KVAh. But the Utility has to provide you (and build their power plants) based on your KVA. If you compute your payback based on this 2.7 A, you will find it is hardly worth the hassle. (For a new installation of course the equipment size and wiring size benefits with high PFs.) And this is why the Utilities get so pissed if your PF is low :-)
I like your comment related to energy savings. This is where energy losses due to material imperfection comes in.. The higher the current drawn, the more the conductor heatsup, thus the more energy is lost. Just imagine the length of wire from utility meter to your motor. He just demonstrated the working principle of a power saving device...
sir good explanation kindly your wriitrn computation to share with me for my personal use and I am willing to give an incentive for kindness and productive explanation asson as possible. thank you so much.
thanks for the knowledge sir , very helpful at our work , hope you have a 3phase calculation at one load and with different load at the same time , thanks again ,
Excellent video first and foremost! Incredibly helpful and easy to follow along! Quick question for you though. After solving for the proper capacitor for the PF correction, you came up with the 82.xx mfd capacitor. I noticed that the capacitor you selected from the HVAC distributor was a plastic body capacitor. Normally in my trade (HVACR) the plastic body capacitors are used in the starting circuit applications and the metal body capacitors are used in the run circuit applications. I'm curious and would like to know if it would make a difference (if any at all) if A: there was a specific reason as to why you used a start capacitor style or B: could you use a run capacitor in lieu of a start capacitor so long as the mfd and voltage rating were matching?
Need to add that lower current means lower heat generated. Therefore, all heat exacerbated aging is slowed. Also, less heat generated in large industrial shops where there are more machines, therefore summer workspace cooling requirements are reduced.
What was the first capacitors size? Is the MFD higher of lower range? I'm assuming you are working with the RUN capacitor? Could changing the MFD help reduce even more amperage draw after completely finding the capacitance of the capacitor? Great instructional video!
A very interesting video showing the effects of reactive power and power factor correction. If you put the amp meter on the wires going to the motor after where the capacitor is connected, I bet the current would be about 5 amps. You are just getting the reactive power the motor requires from the capacitor and not from the power supply. The current on the circuit feeding the motor will be less, and the I square R loss in the circuit from the reactive part of the power will be slightly less (which loss is heating the wire), but in residential situations, the amount of I square R loss is not much so I doubt it would be worth to install such capacitors at motors to save that trivial amount of loss. As others have said, residential electric billing only bills for the real power used, not for any reactive power. But still an interesting exercise to demonstrate power factor correction!
New problem is that "smart meters" are now reading KVA hours not KWatt Hours. The story is that the power company is now charging for Reactive power at residents. I'll be checking my new meter once the sun comes up tomorrow.
It would be interesting to know the value of the original capacitor, I assume it was lower than your computed preferred capacity. Also, your HVAC or electronics guy could test a few of the 20% tolerance units and help you hit your target capacitance. I agree with other comment that raised efficiency should prolong motor life, etc.
Very nice explanation and really big difference after improving pf what about 3 phase motors is there any difference or only use 3 capacitors of the single phase case thanks
I'm trying to understand why the voltage drop across a start winding in a cap start cap run single phase AC induction motor rises so far above the supply voltage. Of course this is the principle of how a potential relay is used to drop the start capacitor out of these motors after a few seconds. Typically in a 240V fed motor, the drop across the start windings is about 360 V. The hand waving explanation in technical college is that back EMF is responsible for that rise. I'm wondering what happens to the inductance of a motor coil as the motor spools up. In an RLC series circuit, that kind of big drop is easy to explain because of the phase shift in the stretch of wire between the run cap and the inductor. Is back EMF phase-shifted compared to incoming voltage? Does motor inductance increase with rotor rpm, to explain this rise? How do you model back EMF in a circuit with classical complex number circuit analysis?
Awesome content! You sir have a way to share very technical information in a way that's easy for me to understand. Got me to thinking though, I have a 7.5hp single phase 240 volt air compressor, would this work on a heavy start up load?
Very nice. Well.ezplained. my question is. This is for one motor only. If i compute for let say 3 motors ac unit. Then only 1 ac is on. Will that 8ncrease my bills ?. Bec of the pf calculation is larger bec i used 3 motors 9n the calculqtion ?
I have a pedestal fan at my shop and it needs a new start cspscitor, only thing is that is very faded where it has the letters because of the sticky material between the cap and the metal cover, so i do not know the value of it. can i use a capacitor fora similar motor? i know harbor freight sells a very similar pedestal fan, i could order one for that motor and use it on mine, would it work?
Ok, I have a meter that gives a wattage and power factor reading. So with all these power terms bring thrown around, what would/should that wattage reading be? TIP, apparent?
I am in the process of replacing both start and run capacitors on a 5 hp 230VAC motor. The information tag does not provide all the discussed information nor does the mfg provide a data sheet. Neither do other mfgs of similar motors. The old caps are damaged such that they are not readable. So I am trying the figure out what capacitor values are needed with limited information. I'm frustrated.
I am building a rotary Three Phase converter. Can I apply the same process to this motor. I assume I would be adding similar capacitors between both legs of the three phase motor.
In a lot of places, consumers don't pay extra for reactive power. The big industries that use large AC motors usually do. Also how much power does the capacitor draw when connected directly to mains?
It should draw very little because once the capacitor has been charged, that energy will circulate throughout the circuit, that is why they are being used. You are basically paying for the initial charge, but then the reactive power is oscillating back and forth between the inductive windings of the motor and the capacitor in synchronism with the sine wave of the applied voltage. It's an interesting concept, almost like a game of ping pong where energy is bouncing back and forth from one state to another.
Hi....at various location there has been a drop in voltage due to many reasons...hence there a rise in current which leads to rise in temp...so please advice how to tackle the issue ....??
They can put that into an excel spreadsheet and it can grind out the numbers for you. The power will change if there is resistive force on the motor shaft. Current should increase. Will that change the capacitor value if there is a load on the motor? Here, you just used the numbers on the tag on the motor. Looks like you were just free wheeling the motor in the lab with no load on it.
The capacitor can only absorb a like amount of reactance, any surplus is redirected back into the supply and is redistributed to other devices within the same circuit that have the ability to absorb it. That is why it is important to accurately size a capacitor, the excess reactive power could register as an increase in current.
@@connorrosekrans7348 It depends on the Utility, penalty charges start to apply to commercial and industrial accounts where the power factor is below 90% as a general rule.
If the motor is only 54 percet etc efficient then it wonter matter what the va is because it can never give more than 54 percent etc, that means if we want the real power which in this case would be 95 percent efficient that means we will have to buy a motor with a bigger va ha ha ha ha....
Like it’s very frustrating I understood and was learning until you jumped and didn’t explain what thr hell is varsc is and ever made any attempt to explain since
In mathematical terms: VarsC is the exact opposite to VArsL. they are both values of reactive power but can be easily confused so the electrical textbooks employ a subscript to clarify this fact. In more simple terms, the motor windings require reactive power to create a magnetic field to induce rotation in the motor. That reactive power can be obtained via a capacitor because they produce reactive power. The entire process is about calculating the amount of reactive power the motor requires to operate, but instead of obtaining it from the electrical outlet in your home, we can charge a capacitor and let that energy oscillate back and forth from the capacitor to the motor windings and back again in a perpetual loop when the motor is in operation. The benefit is that the homeowner does not have to bear the cost of that "Reactive power" to keep the motor running. We need an oscilloscope to show people that there is a difference in the voltage waveforms that the motor windings and capacitors produce, but the main thing to remember is that capacitors and inductors are the polar opposites to each other and we can use capacitors to cancel out the negative effects of what an inductor does inside an electrical circuit.
You really haven’t done anything, you should have checked the amps with the bell on and put the machine under load. You could’ve lost those amps just by taking the belt off and reducing the drag. Sounds like bullshit to me
Lovely to see the combination of THEORY and PRACTICE. Thank you!
Horse-power tells us that it is mechanical power, not electrical power.
This video is so informative, I find it hard to comprehend that in a span of a year it has only 600+ views.
Thank you for your kind words, power factor correction isn't a popular topic but it is important in training future electrical workers.
greetings from the Philippines
Very good explanation and demonstration for power factor correction. It is always nice to see demonstrated with actual equipment instead of just on paper.
Thank you for the nice compliment
You explain the subject of correcting the power factor in a way of understanding for everyone even with a minimum knowledge in electrical. Thanks.
Greetings from Malaysia!! I am a HVAC engineer and totally enjoyed your video!! Now I know how to do PF correction.
I repeated this video more than five times, every minute is so valuable to me! I appreciate it Mr. Levesque, really you are helping us
Thank you for your kind words, greatly appreciated.
Thank you Professor. This is very educational. Love it
Excellent explanation and demonstration! Well done!
Thanks for this comprehensive explanation, now I understand this theme,
I'am saving your video for future uses.
We recently bought an LG fridge, and there is an iPhone app that allows us to monitor the fridge electricity usage and cost. I checked the current usage and multiplied it by 120V, but the result didn't match what the iPhone app reports. It was actually higher. It turns out I overlooked the power factor (PF), which in this case is 0.73 or 73%. This led me to wonder how we could make the fridge more energy-efficient. I haven't taken any action on that front yet, and I'm not sure if I ever will, but I was curious about what value of a capacitor would be needed to correct the power factor. And then, I found Serge's video that answered all of my questions. I want to express my gratitude to Serge for explaining everything so beautifully! The CZcams University.
Very nice, clear, methodical presentation, that was very easy to follow. Thanks for your effort. 🎉
Thank you very much for the lesson , very helpful .👏👏👏
Thanks for an excellent video! I learned so much and will watch several more times.
Excellent demonstration
Super helpful. Great video
Now I understand why we have energy codes, that always should have been in place from day one.
Thank you for your hard work on this video. I appreciate it
Thank you for your kind words, greatly appreciated.🤓
Great video!, thank you for taking the time to create it. You do an excellent job explaining the topics that you are presenting!
Glad it was helpful!
Excellent video. Very informative
This is a well articulated video, very rich and informative in its presentation.Added more insight to my understanding of the topic.Sir, please keep up the good work.Great thanks.
Great set of videos Mr. Levesque. What a valuable resource for electricians in training. Some minor points because of my HVAC background.
1. That capacitor the guy at the HVAC store sold you is a "start" capacitor and will burn out in a few minutes if you use it for "run" duty as you have wired it.
2. We have to be careful in distinguishing between motor efficiency and power factor. They are NOT the same thing.
3. I don't know about Canada, but in the residential USA billing, the meters bill you by KW and not KVA. Although it is always good to have near unity power factor, the fact is that for an existing installation any improvement in PF benefits the Utility more than it does the homeowner. Unless of course if they have a low PF penalty, like in commercial billing rates.
Keep the good stuff coming. Best wishes.
To clarify point 3 above a little more:
If your T.I.P is 333W as you correctly compute in your video, then you are only paying for 333/120 = 2.7 Amps. This is because the utility meter is reading KWh and NOT KVAh. But the Utility has to provide you (and build their power plants) based on your KVA. If you compute your payback based on this 2.7 A, you will find it is hardly worth the hassle. (For a new installation of course the equipment size and wiring size benefits with high PFs.) And this is why the Utilities get so pissed if your PF is low :-)
I like your comment related to energy savings. This is where energy losses due to material imperfection comes in..
The higher the current drawn, the more the conductor heatsup, thus the more energy is lost. Just imagine the length of wire from utility meter to your motor.
He just demonstrated the working principle of a power saving device...
Not only will that Start capacitor burn out but it will likely explode too. He should have used a proper motor Run capacitor.
Great video so informative thank you
sir good explanation kindly your wriitrn computation to share with me for my personal use and I am willing to give an incentive for kindness and productive explanation asson as possible. thank you so much.
Excellent, sir
Very nice class....I learned that
the most awesome lessons
Great video Sir, Pls make video for 3 phase motor also. 🙏🙏🙏🙏🙏
That's a solid motor by looking at just the label.
This is amazing
Sensational Thankyou
You are the best sir 🎩 off to you
thanks for the knowledge sir , very helpful at our work , hope you have a 3phase calculation at one load and with different load at the same time , thanks again ,
eloquently explained
Thank you for your kind words.
subscribed!
Thank you!
Excellent video first and foremost! Incredibly helpful and easy to follow along! Quick question for you though. After solving for the proper capacitor for the PF correction, you came up with the 82.xx mfd capacitor. I noticed that the capacitor you selected from the HVAC distributor was a plastic body capacitor. Normally in my trade (HVACR) the plastic body capacitors are used in the starting circuit applications and the metal body capacitors are used in the run circuit applications. I'm curious and would like to know if it would make a difference (if any at all) if A: there was a specific reason as to why you used a start capacitor style or B: could you use a run capacitor in lieu of a start capacitor so long as the mfd and voltage rating were matching?
Need to add that lower current means lower heat generated. Therefore, all heat exacerbated aging is slowed. Also, less heat generated in large industrial shops where there are more machines, therefore summer workspace cooling requirements are reduced.
That’s a great point
Very informative video, do u hv any video about sizing the starting capacitor of single phase induction motor.
What was the first capacitors size? Is the MFD higher of lower range? I'm assuming you are working with the RUN capacitor? Could changing the MFD help reduce even more amperage draw after completely finding the capacitance of the capacitor? Great instructional video!
A very interesting video showing the effects of reactive power and power factor correction.
If you put the amp meter on the wires going to the motor after where the capacitor is connected, I bet the current would be about 5 amps. You are just getting the reactive power the motor requires from the capacitor and not from the power supply.
The current on the circuit feeding the motor will be less, and the I square R loss in the circuit from the reactive part of the power will be slightly less (which loss is heating the wire), but in residential situations, the amount of I square R loss is not much so I doubt it would be worth to install such capacitors at motors to save that trivial amount of loss.
As others have said, residential electric billing only bills for the real power used, not for any reactive power.
But still an interesting exercise to demonstrate power factor correction!
New problem is that "smart meters" are now reading KVA hours not KWatt Hours. The story is that the power company is now charging for Reactive power at residents. I'll be checking my new meter once the sun comes up tomorrow.
Thanks for this.
Does motor VAr change under load?
It would be interesting to know the value of the original capacitor, I assume it was lower than your computed preferred capacity. Also, your HVAC or electronics guy could test a few of the 20% tolerance units and help you hit your target capacitance. I agree with other comment that raised efficiency should prolong motor life, etc.
nice video
Excellent video! One doubt: What does the sub-L in VarsL stand for?
Again, congrats on the presentation!
Very nice explanation and really big difference after improving pf what about 3 phase motors is there any difference or only use 3 capacitors of the single phase case thanks
thank you sir... wondering why the power factor capasitor does not come with the motor when you purchase the equipment.
I'm trying to understand why the voltage drop across a start winding in a cap start cap run single phase AC induction motor rises so far above the supply voltage. Of course this is the principle of how a potential relay is used to drop the start capacitor out of these motors after a few seconds. Typically in a 240V fed motor, the drop across the start windings is about 360 V. The hand waving explanation in technical college is that back EMF is responsible for that rise. I'm wondering what happens to the inductance of a motor coil as the motor spools up. In an RLC series circuit, that kind of big drop is easy to explain because of the phase shift in the stretch of wire between the run cap and the inductor. Is back EMF phase-shifted compared to incoming voltage? Does motor inductance increase with rotor rpm, to explain this rise? How do you model back EMF in a circuit with classical complex number circuit analysis?
Awesome content! You sir have a way to share very technical information in a way that's easy for me to understand. Got me to thinking though, I have a 7.5hp single phase 240 volt air compressor, would this work on a heavy start up load?
Yes, the technique does not affect the motor's performance in terms of starting torque.
@@sergelevesque6292 would I put the calculated size capacitor between the 2 hot legs feeding the air compressor?
Very nice. Well.ezplained. my question is. This is for one motor only. If i compute for let say 3 motors ac unit. Then only 1 ac is on. Will that 8ncrease my bills ?. Bec of the pf calculation is larger bec i used 3 motors 9n the calculqtion ?
I have a pedestal fan at my shop and it needs a new start cspscitor, only thing is that is very faded where it has the letters because of the sticky material between the cap and the metal cover, so i do not know the value of it. can i use a capacitor fora similar motor? i know harbor freight sells a very similar pedestal fan, i could order one for that motor and use it on mine, would it work?
Ok, I have a meter that gives a wattage and power factor reading. So with all these power terms bring thrown around, what would/should that wattage reading be? TIP, apparent?
is it same formulas for the 3 phase motors ?
I am in the process of replacing both start and run capacitors on a 5 hp 230VAC motor. The information tag does not provide all the discussed information nor does the mfg provide a data sheet. Neither do other mfgs of similar motors. The old caps are damaged such that they are not readable. So I am trying the figure out what capacitor values are needed with limited information. I'm frustrated.
I am building a rotary Three Phase converter. Can I apply the same process to this motor. I assume I would be adding similar capacitors between both legs of the three phase motor.
In a lot of places, consumers don't pay extra for reactive power. The big industries that use large AC motors usually do. Also how much power does the capacitor draw when connected directly to mains?
It should draw very little because once the capacitor has been charged, that energy will circulate throughout the circuit, that is why they are being used. You are basically paying for the initial charge, but then the reactive power is oscillating back and forth between the inductive windings of the motor and the capacitor in synchronism with the sine wave of the applied voltage. It's an interesting concept, almost like a game of ping pong where energy is bouncing back and forth from one state to another.
But what if you connected the capacitor directly to mains with no motor? How much current would that draw?
I understood eveybtint up to varsc what’s thsf stand for
Hello. Can you explain how to use AC capacitors for inverters
Question? Why don’t manufacturers put the right capacitance in to begin with? Is it cost? Is this why some motors have two capacitors?
is it as strong?
Question, How does a motor with no load draw FLA?
Hi....at various location there has been a drop in voltage due to many reasons...hence there a rise in current which leads to rise in temp...so please advice how to tackle the issue ....??
Why does motor manufactures not do power factor correction at the motor production stage, fitting the motor with the capacitor for PFC?
I have the same question! Why manufacturers do not do this pfc if it just cost 1 capacitor?
1. Supply Frequency
2. Possible effect to nominal voltage
3. Production cost
And etc...
They can put that into an excel spreadsheet and it can grind out the numbers for you.
The power will change if there is resistive force on the motor shaft. Current should increase. Will that change the capacitor value if there is a load on the motor? Here, you just used the numbers on the tag on the motor. Looks like you were just free wheeling the motor in the lab with no load on it.
The calculated current was ~3amp, but actual value with capacitor on was only 2amp. What gives?
Sir,
good PM, can you do a demonstration for pf for 3 phase motor for 5 hp 3 phase asynchronous motor. thank you.
Is extra reactance absorbed by capacitor ?
The capacitor can only absorb a like amount of reactance, any surplus is redirected back into the supply and is redistributed to other devices within the same circuit that have the ability to absorb it.
That is why it is important to accurately size a capacitor, the excess reactive power could register as an increase in current.
That’s a start capacitor not for continuous use only short bursts for starting You need to use a run capacitor should be able to get in 80mfd
more efficient if aplly run capacitor
My only comment is I wish he would’ve drawn the power triangle as a way to explain the math.
Depends on the utility. You don’t get charged for peak usage like a commercial customer
I bet you the utility does not charge you for poor power factor. Nothing in this video is incorrect
@@connorrosekrans7348 It depends on the Utility, penalty charges start to apply to commercial and industrial accounts where the power factor is below 90% as a general rule.
o9crank your volume up some.thy
Should of make more of effort to explain each calculation more and down to as simple form as possible
If the motor is only 54 percet etc efficient then it wonter matter what the va is because it can never give more than 54 percent etc, that means if we want the real power which in this case would be 95 percent efficient that means we will have to buy a motor with a bigger va ha ha ha ha....
Like it’s very frustrating I understood and was learning until you jumped and didn’t explain what thr hell is varsc is and ever made any attempt to explain since
In mathematical terms: VarsC is the exact opposite to VArsL. they are both values of reactive power but can be easily confused so the electrical textbooks employ a subscript to clarify this fact. In more simple terms, the motor windings require reactive power to create a magnetic field to induce rotation in the motor. That reactive power can be obtained via a capacitor because they produce reactive power. The entire process is about calculating the amount of reactive power the motor requires to operate, but instead of obtaining it from the electrical outlet in your home, we can charge a capacitor and let that energy oscillate back and forth from the capacitor to the motor windings and back again in a perpetual loop when the motor is in operation. The benefit is that the homeowner does not have to bear the cost of that "Reactive power" to keep the motor running.
We need an oscilloscope to show people that there is a difference in the voltage waveforms that the motor windings and capacitors produce, but the main thing to remember is that capacitors and inductors are the polar opposites to each other and we can use capacitors to cancel out the negative effects of what an inductor does inside an electrical circuit.
You really haven’t done anything, you should have checked the amps with the bell on and put the machine under load. You could’ve lost those amps just by taking the belt off and reducing the drag. Sounds like bullshit to me