AC Theory: How to Calculate Power Factor, Phase Angle & Power Factor Correction Capacitor of a Coil

[@stephaniekuhnert8301]

Hi Joe, I am currently studying for my level 3, 302 scientific principles exam. These are so much more helpful than the smartscreen resources my training provider have given me. Thank you for making this accessible to everyone. I really appreciate your explanations and fantastic teaching skills. Finally! I understand it! :)

[@lukegiles1803]

Thanks!

[@JoeRobinsonTraining]

Aw, I'm so grateful for the super thanks Luke, really appreciate it, thank you.

[@gramamg100]

Joe I studied all this 58 years ago! How much more interesting you make it, and make it so much easier to take in. It’s ideal exercise for my aging brain.

[@LaurenceTaylor-l9k]

just something i picked up. on the capacitance question on the end when you added the 2 on as you forgot. at the bottom you didnt x2 you just did 446.12 times pi times 50

[@Ollyyyy14]

I noticed this the answer should be 7.14 X 10 to the power of -6

[@jameshowgate3290]

is your calculation correct at the end of the video for capacitance? as it look as though you didn't multiply the 446.1 x 2 x pie x 50, but 446.12xpie x 50

[@JoeRobinsonTraining]

Thanks, this has been pointed out and I've added an edit in the description.

[@bdans228]

Superb videos ,I have actually managed to start to understand A.C. iv done 1 year at college and got approximately nothing out of it, spend 2000£ and 8 months of my evening times to end up understanding most of it in 2 days on you tube WHAT A MASSIVE DIFFRENCE A GOOD TEACHER MAKES Thank You very much! there is a small calculation error you have made at the end ( just to prove that i actually followed right to the end) 😉

[@no_short_circuit]

Well done Joe. It all falls in to place now - like a penny dropping! This series has been extremely helpful to me (and I'm sure many others). I remember those cosine/tangent/sine tables well, also the dreaded log tables and slide rule! Thanks again.

[@ianclark958]

I think theres a calculator error there joe. You didn't put the times after the inductive reactance

[@JoeRobinsonTraining]

Thanks Ian, added an edit to the description.

[@JoeRobinsonTraining]

Thanks very much, glad that it's made sense to the end. Not a difficult subject but takes a while to get through it all! Stay tuned for more and always feel free to suggest ideas for future content. 👍

[@leejohnson-smith3231]

hi Joe your videos are a massive help and in hope the ads reward you accordingly. Am I being stupid or did you on the last calculation not put x 2 in the calculator? just mine come up with 7.14 micro farads. Have I done this wrong? thanks again for all the help your videos give.

[@JoeRobinsonTraining]

Ah thanks very much, I'm glad they're helping. I'm afraid I was the stupid one and made a mistake on the final calc. If you check the video description I explain it there. Thanks again and well done for spotting it! 👍👍👍

[@eddieking7736]

Well done. Clear explanation, everything falls into place, better than any text book I had to read more years ago than I want to remember. 👍

[@JoeRobinsonTraining]

Ah, thanks so much, glad it's been helpful and clear. Stay tuned for more!

[@bartonsmith1215]

Thank you so Much Joe! I recently re-enrolled to finish my electrical trade after a 15 year hiatus from the industry, I was really struggling with AC circuits over the past few weeks, Your series of videos has really helped me get on top of the AC principles and the associated maths behind them. I really appreciate you taking the time to put these videos together! Do you have a patreon or anything similar? I would like to send you some Beer money!

[@JoeRobinsonTraining]

You are more than welcome. I'm really glad the videos helped you out, its a tricky subject area and takes a bit of work to explain and understand so well done for sticking at it. I've thought about setting up a Patreon account but I'm not sure there's enough people who'd be willing to contribute to it. 😂 Thanks for the feedback and your kind offer it's very much appreciated.

[@jamesward9570]

Started work in 1974 as a electrical apprentice Relearning all the theory to. Keep my brain active Thank you Joe Terrific teacher

[@weavercattleco]

Here's some other equations you can use to double check your answers with 😉 ω = 2πf ( Angular Speed - Radians / Second ) L = (1/ω)² / C C = (1/ω)² / L Ex. C = [1 / 2π(50Hz)]² / (1.42H) = 7.135µF Resonant Frequency (f) - The frequency at which Inductive & Capacitive reactance cancel each other out where impedance (Z) is equal to resistance part of circuit. Z = √[ R² + (Xᴸ - Xᶜ)² ] --- No reactance (Xᴸ - Xᶜ) = 0 Xᴸ = Xᶜ or 2πfL = 1/(2πfL) ... solve for (f). ---> (f) = 1 / 2π√(L·C) These are good equations to have in your arsenal 😊

[@jamesward9570]

Absolutely brilliant

[@bartom309]

Thank you for these videos they are helping me with practise for my EAL lvl 3 exam

[@aerofart]

Excellent instruction. I’d be celebrating if the trade school I am currently attending (on the “great” United States) was half as good. Thanks for your contribution!

[@DCMamvcivmEvony]

I have always struggled with transposition never quite clicked. The way you just explained it though made it seem so simple. 🙂

[@JoeRobinsonTraining]

Thanks Daniel, would a whole video on transposition help?

[@DCMamvcivmEvony]

It would indeed, I think transposition is one of those key fundamentals to learn. I never quite get it to stay in my head for whatever reason. Have to look it up every time.

[@JoeRobinsonTraining]

I'll see what I can do!

[@DCMamvcivmEvony]

Amazing thankyou.

[@ianclark8194]

Excellent as always. Can you do a series on Desmos next please!

[@JoeRobinsonTraining]

Ooh, that's an interesting idea, you've got to guarantee me at least one view though!

[@ianclark8194]

@@JoeRobinsonTraining A bit bespoke possibly, but I'm sure there may well be other trainers out there who would benefit from a bit of an insight. Could be used for graphical representation of combining trig formula I suppose

[@JoeRobinsonTraining]

I'll see what I can do!

[@Adrian-Carstea]

12:35 you forget the multiply sign when you introduce the capacitance value, so the results are way off.

[@JoeRobinsonTraining]

Thanks, this has been pointed out and I've added an edit in the description.

[@Adrian-Carstea]

Sorry, didn't read it.

[@jasonwarne1896]

on your last calculation Joe it looks like you've calculated 1/ 446.12 x pi x 50 rather than 1/ 446.1 x 2 x pi x 50 which comes out at 7.14 mF . i've probably missed something . P.s thankyou for all your great work, you've helped me understand what i thought was the impossible!

[@Adrian-Carstea]

at 2:02 you said that power factor is R/Z, which is corect in this case. What if I have a circuit in which a resistor and an inductor are in parallel. The impedance will be smaller than the resistance, and we end up with a pf more than 1, which is imposible. So, can you use the same formula for pf in a parallel circuit? Or am i missing something?

[@JoeRobinsonTraining]

Sounds like a good premise for a video!

[@Adrian-Carstea]

I figured it out, in a series circuit current is the same so PF=real power/apparent power=(I^2 × R) / (I^2 x Z) = R/Z . In a parallel circuit voltage is the same so PF=(V^2 / R) / (V^2 / Z) = Z/R

[@sparkspot8631]

Professional and to the point content. Thank you! What would happen to the voltage/current phase relationship if the capacitor was of a higher value than 14.27 micro Farad?

[@MrAshwindersingh]

This is amazing

[@gbelectricks]

Hiya great video again joe but I’m struggling to follow your capacitance calculation at the end of this video. Admittedly I’m using an iPhone scientific calculator, I think without the eng button. Is there a way around this problem (no eng button)? I can’t seem to come out with 14.27micro farads??

[@JoeRobinsonTraining]

Hi, the problem is I'm a doofus and made a mistake when entering the calc, I've added an edit in the description which runs as follows: the final Capacitance calculation is wrong as I didn't press the multiplication button on the bottom line, the answer is 7.14μF. My sincere apologies for any confusion and thanks for asking. 👍

[@gbelectricks]

Joe Robinson Training ha ha!! No problems joe. I thought I was going mad🤣🤣

[@JoeRobinsonTraining]

😂 Nope, I have to make the videos in my spare time at work and I was trying to get it done in my lunch break on a Friday with learners queuing up at the door. Clearly the pressure got to me! 😂😂🤣

[@mrdalescott83]

Haha, just been going round in circles trying to match your last equation then noticed you missed the multiplier then read your comments. It actually helped with the learning though. Your are a great teacher, thank you for the videos.

[@alexogaj8177]

forgot to multiply by 2 but great video

[@josephsigley5998]

At 13:35 you forgot to put the 2x on the pi when trying to find the capacitance. It should be 7.14uF not 14.27

[@yerzhansarsenov6760]

Hi, Joe. Are Zs in RL and C circiuts the same? I calcutated C from voltage drop (14,99 V) and VAr (0,5) of a coil. I get C = 6.62 microF. I did this way because parallel C does not have R in its circuit. Am I wrong? Could you please clarify the right way of C calculating.

[@GSHElectrical]

👀

[@jeffreyyussuff9526]

is the inverse cosine (Cos to the power of -1) the same as 1/ cos ( 1 divided by cos), just like x to the power of -1 is the same as 1 over x (1/x) Great vids by the way. Do you have any info on inspection and testing

[@JoeRobinsonTraining]

Great question, you'd think so but it's not, it's the inverse cosine or arc cos. Basically it's giving the calculator a cosine value and asking it what angle had that cosine value. 👍

[@ezio_g]

After adding the Pf corrective capacitor (C= 14.27uf) in parallel to the circuit, theta ( ⍬ ) becomes zero and Pf =1 which means the current does not lag the voltage anymore, there is NO "inductive reactance" in the circuit, there is no waste of power, the "apparent power" is in phase with the "true power" and the electric company will NOT add a fine on our electric bill. True???

[@ezio_g]

Two years later I just went through this again and realized that the corrective cap is 7.14uf and not 14.27uf. The error was in the calculator.

[@mohammedsaeed1852]

good job but you have forgotten multiply by two in Xc equation in order find Xc

[@BIGRIP87]

wow this is amazing can you please teach, how to calculate inductance of EI IRON core using inductance formula ( i can't find formula for EI core)

[@thomasgreenwood3086]

but you are using power factor from ac an dc circuit how do you find just it ac circuits

[@kdi9049]

Idk what im doing wrong but my values after calculation are way off from yours even after the edit. Im getting different results idk if im just dumb or what. 1÷446.1×2×pie×50 is giving me .704... 😅

[@Ent-4]

❤

[@ahmednor5806]

🙏🙏🌹🌹

[@kimerafahim4429]

The C is worng due to the poor imputing of value in the calc kind forgot to multiple the 2 in the denominator

[@tilidie5272]

12:35 ooh little mistake there joe i expect better from you lol seriously tho id be lost without you!