This is a very nice explanation of the capacitor value calculation, but it is misleading with respect to savings. In the USA, utility companies only bill small consumers for actual power, not apparent power.. Small consumers save nothing by power factor compensation, but they can free up circuit capacity. Large consumers have a more complicated billing structure that may include some charge for low power factor. I suspect the same is true in Canada and in other parts of the world. There is no cost to utilities to produce reactive power, but it does reduce their capacity and and the transmission losses have a cost. Utilities may install power factor compensation in substations and even on poles to reduce the transmission and capacity losses.
You can't really determine the cap value from nameplate numbers. It is a function of motor loading. You put caps on & vary cap & note the current & go for minimum. You save nothing as far as utility is concerned. Home power is charged based on real power, not reactive power. The only "saving" is less current in your home's wiring. This would be useful only if heavy load is on the edge of tripping breaker. The cap you are using looks like "motor starting cap". These are AC nonpolarized caps designed for use a few seconds at a time only! You need AC oil caps if you plan on running the load for any significant period of time. They are large for the microfarads you get! You also need to deal with the surge on turn-on. This will tear up the appliance's on-off switch. A better thing to do with this motor (assuming it has either starting cap internally, in the bulge on the motor's top, or it is split-phase start, both with centrifugal switch cutout) is to put an AC cap on the "starting" winding permanently (smaller than the starting cap) sized to balance the 2 phases in the motor internally WHEN RUNNING. This will make the motor run cooler & consume less real power, & will reduce vibration.
Would be nice to also clamp an ampmeter on the black capacitor wire to show the reactive current. And a killawatt device on the input to demonstrate an improved power factor.
I'm learning about PF correction online..you sir are the best teacher I have come across!!! That was excellent explanation of exactly how power factor works that it was so much easier to understand than my course I'm doing at the moment! Subbed and liked 👍 thank you so much and cheers from Australia 👍
Electronic variable speed controllers generally will not tolerate power factor correction at the motor. Power factor correction capacitors on the line side of the controller are likely to cause problems also. If such a system needs anything it will be a harmonic filter or inductance on the line side to prevent the controller from interfering with other equipment.
What brands and types of capacitor should I use on an old 1940s transformer welder? There is no markings on the capacitor. The equipment plate has these specs, Primary volts, 230v 60hz, max 37 amps, output 180amps max at 25v, OCV 52v-65v, F.L.P.F. 75%.
@@6615Dean those tests were conducted with a megger but it only went up to 1000 volts. A visual inspection should be performed in addition. That was one of the points I was trying to make in the video.
Im not sure our company owns a Megger haha or cares… So with a volt meter I could test the windings to ensure each winding has the same amount of resistance, test continuity to ensure no windings or phases are compromised, check phases to ground. But without a Megger I cannot properly check the windings can safely handle 600v-1000v and that the insulation is not compromised? Correct? I’ll do my best to get a Megger on site and I’ve suggested this already. We shall see.
Thank you so much! I went along with your lesson and built a spreadsheet to do the calculations at the same time. I have a much better understanding and greatly appreciate the time you put into the video! Well done!
As asked by Muhammad 1year ago. Why are motors produced with this inefficiency in them? Are the motors with two capacitors on them corrected already. Im nowhere near a electrician just always trying to learn a bit of something. Thanks for the lesson.
What I wonder is if the harmonic distortion (I) has any consequence in maintaining the magnetic field in the motor coils. I want to think it's meaningless compared to correcting PF.
Thank you for this! (I'll be back soon for 3Ph classes 🙂) Meanwhile, I have a diaphragm (inductive load) pond air-pump that at 120.8v meters at 78w (claimed) and 1.58a (claimed), but it didn't make sense to me. I have some homework to do and a plan. And now I can imagine how makers size run caps for CSCR vs CSIR motors. That said, It seems that any CSIR ought to be checked out.
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?
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
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
Hi, ive got a 300v 3phase motor and I'm trying to put an encoder on it. Part of calibrating the encoder is I'm suppose to lock the motor and then set the encoder to zero. How do I know what's a safe voltage and current i can connect to the phase 1 and phase 2 wires without burning the windings up but will rotate and lock the rotor to the zero position? Thanks
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.
Dear Serge, How many microfarads of capacitor do I have to use for 10A 270V active load ? I am trying to power my 2500w boiler with DC direct from PV panels. I destroyed 2 SSR relays so far. The relays are raited for 40A 400V DC. Nevertheless, they burned. I have no explanation why it happened. I planned to use 60A 600V SSR relay with IGBT transistor inside. I found this video, and I am hopeful that the capacitor will do the trick of sprakless switching off the circuit.
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.
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....
Well done! Nice demonstration. One more sudgested experiment would be: to take 3phase star connected induction motor, connect its centre (neutral) point to neutral, and than disconnect one of the phases. Turn power on/off, show currents and also do a load test. This would be a good way to show the advantages of having 4 wires (with neutral) connected from motor to a distribution line in a single phase fault scenarios (especially for the parts of the world where phase faults are frequent and thay don't have phase control rellays.
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.
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 ....??
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.
