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Jonathan Gracey
Приєднався 9 січ 2008
Electrical Engineering Concepts Explained
Arc Flash Boundary and Incident Energy explanation
Arc Flash is a complex topic with assorted technical terms often used. Two of these terms are Arc Flash Boundary and Incident Energy which are explained in this video.
Переглядів: 1 321
Відео
Calculate Generator Subtransient Reactance X''
Переглядів 13 тис.4 роки тому
Discussion on how to calculate/convert alternator subtransient reactance X'' to generator subtransient reactance. Includes calculation example. Obtaining the correct subtransient reactance is needed to correctly calculate generator fault current contribution.
Calculating Generator Fault Current
Переглядів 16 тис.4 роки тому
Calculating generator fault current discussion and example. Conceptual discussion of symmetrical and asymmetrical short circuit current. Symmetrical sub transient fault current calculation example using a typical three phase generator.
Calculate arc current for arc flash energy - NFPA 70E
Переглядів 7 тис.5 років тому
Example shows how to calculate the arcing current per NFPA 70E Annex D.4.2. Determining the arcing current is required to use Annex D.4.3 to calculate the arc flash incident energy shown in another video.
Calculate arc flash energy for fuse classes L and RK1 - NFPA 70E
Переглядів 5276 років тому
Covers one method of finding the incident energy in cal/cm^2 of an arc flash when using class L and RK1 fuses. One example of how to use NFPA 70E Annex D.4.6 to calculate the arc flash incident energy using a 2000A Class L fuse.
Calculate incident energy of arc flash - NFPA 70E
Переглядів 13 тис.6 років тому
Example shows how to use NFPA 70E annex D.4.3 to calculate the incident energy in cal/cm^2 of an arc flash incident on systems 208V through 15,000V. Formula works for all fuses and circuit breakers. Using the calculated incident energy one can determine the appropriate level of PPE for the potential arc flash hazard.
Understanding Current Limit Fuses and let through current
Переглядів 42 тис.6 років тому
Examples are provided explaining the fuse graphs of a current limiting fuse. First over current protection is discussed and the TCC fuse melt chart is examined with examples. Next we look at the current limitation curves to determine the symmetrical let through current and an example is provided. A class L fuse is used in the examples
Replace trunk lid torsion bar (trunk spring) on Toyota Corolla
Переглядів 120 тис.6 років тому
Quick video showing how to reinstall or replace torsion trunk bar (the trunk spring unit) in a Toyota Corolla 2014
Fault Current Finder
Переглядів 7927 років тому
Available on iOS devices, search Fault Current Finder Fault Current Finder is an advanced system modeling tool. It models an electrical distribution system to determine the available fault current anywhere within the system. This useful tool helps Engineers, Electricians and Facility Managers evaluate if devices and equipment such as fuses, circuit breakers, panels, switchboards and switches ar...
Electric Motor power source DC vs AC single phase and 3 phase
Переглядів 1,8 тис.8 років тому
Illustrated discussion of electric motor characteristics when powered by DC, single phase AC or three phase AC. Voltage, current, power factor, phase cutting, VFD and load considerations discussed
Understanding 3 Phase Power in Delta and Wye Systems
Переглядів 68 тис.8 років тому
An overview of 3 phase power in Delta and Wye systems. Includes waveform discussion, Line to Line and Line to neutral voltage topics and formulas. A simplified building power distribution system is explained with a delta to wye transformer example.
Understanding the Power Triangle and Power Factor
Переглядів 34 тис.8 років тому
This example provides a quick review of right triangle trig and then applies it to the Power Triangle. Watts [W], Volt-Amps[VA] and Reactive Power [VAR] are considered and the concept of Power Factor is discussed with real world application of unity and inductive loads leading it increased amp power draw.
Thank you by the explanation. My best regards from Brazil.
Thanks Jonathan, jus one comment regarding the K1 factor value is (-0.555)
Yes typo thanks for the note.
@@graceyj20 I appreciate your feedback, can you illustrate the selection of clearing time for the fuse in this particular example, it's not clear?
@@MrBelal79 Each fuse or circuit breaker has it's own clearing time characteristics. See another video here introducing fuse clearing time here ua-cam.com/video/P5hZ1WYfXB4/v-deo.html
@@graceyj20 Thanks for your feedback, is that applies also to MCCs with 400 A Fused Disconnect Switch ?
@@MrBelal79 Yes see NFPA 70E annex D4 for details.
Thanks. Good job
Thanks for explaining this topic , nice explanation
I had to replace my trunk hinges on a 14 Corolla and could not remember how the torsion bars were installed. Your video solved my headache. Thanks a bunch. .
Glad it helped
Hi Jonathan, Can you please clarify how you take D = 455 mm.
Hi, NPFA Annex D4.3 references 455mm (18") as a typical LV value for MCC's & panels.
Thank you TREMENDOUSLY...I was trying for 20 minutes, almost lost some fingers; in a Lexus ES it is very difficult to see or move that hinge while you THINK you are doing the right thing. Once I saw your video and found it, BOOM done in 10 seconds!
Nice! Glad it helped
Been driving my car for a year with a heavy trunk. Fixed it myself today, all thanks to your video 🙌🏼🙌🏼.. Thank you so muchhhhh
Nice!
Where does conductor length factor in
The conductor length/size/properties reduces the fault current from the source to the fuse due to it's impedance. Calculating the available fault current is not covered in this video.
@@graceyj20 I was binging and just put the comment on the current vid I was on. Thanks
Thanks
Delta can have a neutral if it is a 120 Delta secondary. It has a middle tap kind of like a split phase transformer. Yes Delta can have a neutral.
Yes, high leg delta's can have a neutral but they're not that common in most areas. The comments are generalized to cover the most common circumstances.
Hello, any recommendations for an application to calculate the NH Fuse Melting Time?
Had a hard time finding a relevant video for my 2018 toyota corolla trunk torsion bar which suddenly came loose. Your video was right on. Fix it in minutes. Thanks.
Gracuas al fin lo arme!!!
Wow! Thanks bro, you save the day. You are the only guy who perfectly demonstrates how and why the value of minimum fusing current is greater than the rated current of the fuse! I can sleep well tonight, Cheers!
Love it
Thank you very much for the video
Glad it was helpful!
Thank you
I have a 1998 Toyota Corrola LE. I have 2 swing arms on the turnk that came out of the trunk spring on the LEFT side.I can't seem to find a video on this. every video is for the single arm right side:. Can you help me. Thanks
Sorry I'm not familiar with that configuration but hope you able to find a resource to figure it out
Deltas can absolutely have neutrals. The 120/240 Delta is very common. 2 phases will be 120V to neutral and the high leg will be 208V to neutral.
Thank you so much!
Great stuff. Helped me out a bunch!
This video help me a lot thanks for that mate
So good, thank you!
Brother thanks man, I just found your thing. I'm sitting here on a hill to hold my trunk open on my sonata and it worked like a charm. You rock brother. Thanks for helping somebody out. My best to you
Glad it helped!
are these tables and values only found in that expensive nfpa book? i cant seem to find that exact table you used online
i found a 2015 edition online!!!!!
You can view the last several revisions of NFPA 70E (and many others) through NFPA.org for free. It's not great but there is a free option.
It's free on their site. And also it's free on Pira hfndkejrjn bay
yes just what i needed
I’m an electrician and I remember learning this in the first 4 months into the trade!
This is my 4th week.
Good refresher for an Electrician!
Thanks a bunch mr saved me a headache. 👍
Hi Jonathan, thank you for the clear explanation of the concept. In the calculation of your Normalized Incident Energy Level, the K_1 value used was a positive value (0.555), what would be the reason the value was positive in the equation? Thank you.
Thanks for the question. The missing negative sign in the equation was a typo. It's a negative value as indicated on the right had side of the screen and if you go through the calculation with it as a negative you'll note it equates to the lg en value shown on the next line, 0.68298.
Excelente 👌 muchas gracias!!
i was downloading the catalog time-current characteristics of the nh fuse, but in the picture above the graph there is no description of the current rating. can you help me?
You should contact the manufacturer if their data sheet isn't properly marked.
Very nice video by Mr.Gracey, Could you please make video on Arc flash Boundary calculation
Very good video
sinewave???
Why cant you just bend it backwards and reinstall ? Should last for a while
Thank you!
hey jonathan what's up
Thank you
Thank you so much! I couldn't figure this out by myself.
98
Thank you
if we start at 100k and you want to reduce for MCB at 10k, then you have to reduce twice?
That depends on the protective device characteristics and the short circuit current sources throughout the system. That said, if you're looking to reduce for a 10KAIC rated MCB you should confirm with the MCB manufacturer that the make/model of the fuse your planing to use is recognized for series rating with that specific MCB.
can the torsion bar brackets be got separately
Thankyou Jonathan, the clearest explanation I have seen yet.
Hello Johnatan, I bended those metal rods but they are still in place somehow, the trunk closes fine. Which is their purpose?
Hi, how would you calculate the tripping current of the circuit breaker if it set to 125%? Thank you in advance.
You have to look at the time to current curves for the specific breaker. You should be able to obtain these from the circuit breaker manufacturer.
Hi Jonathan i like your lecture. Thanks
Glad you found it helpful
Thanks for saving the day