Can you show your work for the infinite bus calculation. I can not get the 31374 amps.
@Brainfiller2 ай бұрын
Sure thing. SCA = short circuit amps (on secondary) FLA2 = Full Load Amps (on secondary) SCA = (FLA2 x 100) / %Z FLA2 = 1500 kVA / [sqrt(3) x 0.48 kV] = 1804 Amps SCA = [1804 Amps x 100] / 5.75 SCA = 31,374 Amps
@timfrey60872 ай бұрын
Thank you
@9999afshin4 ай бұрын
Nice
@DragnBarZ5 ай бұрын
i just got hired to be a technician at a old hydroelectric powerhouse built in the 20s and we have a bunch of these old GE relays. thank you for the explanation. i’ll be checking for more videos on these old components.
@j818515 ай бұрын
Jim, I deeply admire and enjoy your lectures and think you are a stable resource that does not bend to the wind of trends. I recommend you as the "Arc Flash Expert" in all my ESWP classes. You are a lighthouse in the storm of misinformation out there.
@Brainfiller5 ай бұрын
Thank you for your kind words and support! Best Wishes!
@KAFKUBA5 ай бұрын
You answered that question!
@Sparky-ww5re7 ай бұрын
Nice informational note and clarification, but you could easily argue that items 3 and 4 overlap, because if you have a breaker with an interrupting rating of 10kA, and you install it in an application were the available fault current is 20kA, then the equipment is not being used in accordance with the installations for the listing and labeling
@jamesballah52237 ай бұрын
nice presentation
@Brainfiller7 ай бұрын
Thanks a lot
@LIM_Khuan7 ай бұрын
thanks , is great
@educationpower18237 ай бұрын
Thanks Jim this is great! Appreciate all you do Robert from Omaha
@Sparky-ww5re8 ай бұрын
Excellent presentation and very important info, since the available fault current and incident energy can behave like a double edge sword in that attempts to reduce the available fault current by using impedance grounding or similar measures can increase the clearing time of the OCPD to a point of actually increasing the incident energy.
@Brainfiller7 ай бұрын
Exactly! Lots of moving parts with this.
@user-yo9ny9lx4e8 ай бұрын
Thank you
@channel123819 ай бұрын
2:22 😂😂😂 👌 nailed it! Enjoyed the lecture
@carlitosways644210 ай бұрын
Where can find the Part 2?
@charlessmith26311 ай бұрын
Jim is saying this - if an unauthorized person trespasses or crosses the Arc Flash Boundary line - PUSH THEM BACK! PHYSICALLY PUSH THEM BACK IF NEED TO. This is the only way to keep that bad actor from being blasted away or burned away seriously or fatally from an arc flash. Electricity, especially high-voltage current, is not a joke. This is very serious business, and must be respected very profoundly. And in arc flash situations, extremely serious. You mess up or screw up even very slightly in arc flash situations - you get blasted or burned up to death in just seconds!!!
@charlessmith26311 ай бұрын
I was lucky to survive a 130V arc flash from a very bad outlet in my home in 1991. Trying to plug a night light. There was a bright flash and a bit of a pop but the circuit breaker tripped in 1/32 of a second - otherwise I would have been electrocuted. I was uninjured despite something like 2 cal/cm3 of short circuit fault. But if this were a 60,000 volt arc flash if I plugged in that same night light, since I was without PPE, I would have 4th degree burns in the face and the neck - maybe 5th degree burns, because of the 35,000F superheated plasma air - and also thrown back from the "blast" at speeds as high as 200 mph - and I would have died instantly from my injuries.
@510purple11 ай бұрын
I work for a 3rd party testing company. I did infrared scans today and the electrician opening up the equipment for me dropped the cover onto the lugs inside the transformer and it tripped the panel feeding it. It also tripped the main breaker in the main electrical room. Why did a feeder panel trip the main?
@Brainfiller11 ай бұрын
Could be a couple of reasons. 1) Did the main have ground fault protection? Sometimes if it is ground fault, depending on the settings, the main may trip in addition to the feeder. 2) Higher magnitude faults can cause the instantaneous of overcurrent devices to trip. So it is possible that the current caused the feeder and the main to trip. To be sure, that would require reviewing the devices and the respective time current curves. Thanks for your comment. 3) I hope no one was hurt. That could have been disastrous. 4) NFPA 70E provides much needed guidance for safe work practices. Thanks for your comment!
@510purple11 ай бұрын
@Brainfiller thanks for responding. Thankfully, no one was injured. As for the main breaker, I'm pretty sure it has ground fault. And that would make sense because it was more of a ground fault than a short circuit.
@plchacker11 ай бұрын
130.12? Is there any way to change this word salad? I understand the intent, but it looks like a team of HR/Safety, Lawyers and ISO freaks wrote this. It could simply say, "Before any work is done to electrical equipment/conductors, care must be taken to insure all possible electrical sources have been put into an electrically safe condition." It is suppose to address the possibility of multiple sources or back feeding on a circuit that is being worked on. Every qualified worker would be well aware of this hazard and will take precautionary steps.
@Brainfiller11 ай бұрын
The best way to initiate a change is to submit Public Input (proposal) for the 2027 edition a NFPA.org. The closing date is June 4, 2024. Thanks for your comment.
@plchacker11 ай бұрын
Is there any chance that there will be higher categories of PPE added since we have more capable PPE? I honestly expected this update for 2024.
@j818515 ай бұрын
Why? Hierarchy of controls suggests Eliminate the hazard. Have we all not looked at Doughty and Neal in the 90's and IEEE/NFPA collaboration of the early 2000's? 5-12 calorie arc flash 140 db SPL consistently. You guys can wear all the 100 cal stuff you want. My students are trained to reduce or eliminate the hazard. Their leaders need to be trained that convenience and prevention of financial loss still does not justify the risk. LOOK AT THE controls pyramid.. PPE IS THE TIP OF THE SPEAR!! I do NOT care about improvements in PPE, PPE at best is marginal to keep you from being dead. Sound is sound. 141 DB SPL is around 2160 psi pressure to the body. Why are we so adamant to make it electrically safe when in doing so we expose people to huge electrical explosion risk glibly "oh the PPE has improved!!" Really? The Psychics of the arc flash is the same as it was 40 years ago when Ralph Lee published "Arc Flash the the other Electrical Hazard". Yeah I hear you all this is some old guy. Yeah following the rules is why I am still standing at 72. Think about it. Oh, and remember all the whiz bang relaying and fiber loops you do still reduce the hazard but 5-12 calories (rather low values) still generate the maximum OSHA allowable exposure. Again think about it.
@Brainfiller5 ай бұрын
@@j81851 I was part of the steering committee of the final incarnation of the IEEE/NFPA collaboration and on the 70 Committee. There is quite a bit of inertia so veering from the existing categories in the near term is unlikely.
@truthseeker1328 Жыл бұрын
Hi Jim, Very good information video. While I fully agree that the new verbiage to test for absence of "at each point of work" is a long overdue clarification that will help reduce confusion, minimize accidents and is a step in the right direction, there still needs to be additional instructions to re-perform absence of voltage testing when working in large electrical equipment such as switchgears or MCCs. The panelboard you showed is a fairly simple electrical design with only one or more sources entering the line side of the main breaker. As long as all the sources are correctly LOTO, then testing the line side of the main breaker will be adequate for everything downstream "at each point of work". However, with very large distribution equipment such as switchgears or MCCs, there can be multiple different feeders entering different cubicles and parts of the same equipment. In some industries, not all the feeders can be isolated and must remain energized for critical loads. In such cases, the absence of voltage test, needs to be reperformed as the worker moves from cubicle to cubicle and part to part. There has been numerous accidents and operational experience where workers entered a cubicle that was thought to be de-energized (ESWC) but contained energized parts, resulting in fatalities and serious injuries, because they assumed their initial absence of voltage test was adequate. If the workers had reperformed the absence of voltage test "test before touch" then the hazardous condition identified and the accident averted. Thanks and keep up the great job.
@jerrydaugherty4657 Жыл бұрын
Excellent presentation, Jim, thank you very much! This is a topic that is far too often misunderstood as people improperly equate "high fault current with high incident energy".
@Brainfiller7 ай бұрын
Thanks for your comment.
@educationpower1823 Жыл бұрын
Also, I have discovered an alarming number of people who do not read the instructions from manufacturer on how to properly use a noncontact test instrument..for example the need to be properly grounded to avoid false readings etc. Thoughts of untrained people relying on this method?
@Brainfiller Жыл бұрын
It's like so many other things. Training is the key and without it, things can go terribly wrong.
@educationpower1823 Жыл бұрын
At speed of light
@educationpower1823 Жыл бұрын
Jim. I teach that shock is tramua forced on the body..like car accident, baseball bat upside head. etc. Electri shock is electrical trauma forced on body at spoed of light..Robert from Omaha
@Brainfiller Жыл бұрын
Serious shock needs medical attention even if the person seems to be OK. Sometimes effects aren't noticed until sometime later.
@bobcocampo Жыл бұрын
What are the arc flash ratings of metal enclosure covers of panelboards and switchgears
@Brainfiller Жыл бұрын
Metal enclosure covers, panelboards and switch gear do not have arc ratings like PPE. However, some equipment like switchgear can be designed based on standards such as C37. 20.7. This equipment, known as arc resistant, is designed to contain the energy during an arc flash if it is properly closed.
@bobcocampo Жыл бұрын
@@Brainfiller Right now it has no rating. However, if cover will have rating it will assure that the person in front of the switchgear. This may allow person in front of the switchgear just monitoring to be safe without a PPE. If PPE can have a test on Cal per m2 then enclosure covers should have this test too.
@Brainfiller Жыл бұрын
@@bobcocampo Equipment can go thought testing to be arc rated. This is not an arc rating. It is the ability of the equipment to contain the energy. PASS/FAIL not a specific arc rating like PPE. Two different things.
@s3ltep Жыл бұрын
how we can Z0 value?
@MR-nl8xr Жыл бұрын
So the lesser of 2 evils is choose an open air circuit if someone suspects there is a AB hazard, in a task.
@educationpower1823 Жыл бұрын
Really appreciated your efforts and time in this Jim. Great job!
@spencerhamilton6253 Жыл бұрын
This is a 500kv circuit switcher. The phase closest to the camera has one of the two interrupters failed . You can see the interrupter on the left take the entire arc and the other interrupter dosent open which maintains the arc when the isolating switch starts to open.
i was looking for harmonics relative to a song on guitar, and now my brain has flashburn.
@thycattuongtran9885 Жыл бұрын
Great❤❤❤
@noill911 Жыл бұрын
Thank you so much
@vincentallardmentoratcoach4405 Жыл бұрын
Thanks !! How to Create a Six-Pulse Waveform ?
@joea.golgiri53142 жыл бұрын
You are the man!
@elsieoneill61812 жыл бұрын
Used to wear I think 12 rated arc flash coveralls at ioc in Labrador . Was always told you would get messed up being launched from the blast regardless. Hopefully won't have to find out.
@busraahmed17082 жыл бұрын
high level english
@danox19982 жыл бұрын
Great video this! Straight to the point!
@brockpace89962 жыл бұрын
What is the difference between the handbook 70e and the standard 70e?
@reuvenmoshe67122 жыл бұрын
what is the precentage on the waves (39%)?
@timm83112 жыл бұрын
Nice video. A great refresher. Are you going to continue the coordination series? Thx
@VikashKumar-tk3de2 жыл бұрын
Nice video
@sripradhaiyengar99802 жыл бұрын
Thank you so much! 😄
@rohitbhardwaj80982 жыл бұрын
Great! Valuable information. Thanks a lot🙏
@Brainfiller2 жыл бұрын
Glad it was helpful!
@DanBullard2 жыл бұрын
You said a lot and nothing. I have to give you credit for showing real waveforms, not made up waves like most, but you need to take a look at my stuff to see how harmonics really work.
@boonyalitt2393 жыл бұрын
Great Video. I have a question regarding the arc flash, in case a office for electrician is in the switchgear room. Moreover, the location is within the arc flash boundary. So, we are not sure that they have to wear the arc flash PPE all the time or not? Is there any standard or practice that we can refer to? Thanks in advance for your advice.