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  1. HamburgerHelper

    Mimic Control vs Display Control

    Mbrooke, I would just go with whatever is convention in your facility on push open and close. There is a lot of times logic that supervises a breaker opening or closing. If that is the case, you aren't going to get around operating the breaker without a working relay so using the front push...
  2. HamburgerHelper

    symmetrical components

    You need too look at how to build sequence networks of a system to understand which components are involved in each type of fault. Sequence networks are used to determine the fault currents of unbalanced faults. The sequence network is created and then can be transferred back to regular phase...
  3. HamburgerHelper

    Non-Profit Engineering Firm

    drawoh, I just want to grow a business to service an industry and make a reasonable amount of money doing it. For example, what would stop me from starting a business that services the renewables industry and operates as a non-profit? I expect or want to pay good employees well and really...
  4. HamburgerHelper

    Loadability of a Distance POTT Protection Scheme - NERC PRC-023-4 Guidelines unclear

    Jwatty, Those are stable conditions. What they don't want is for the lines to trip out before an operator can implement a mitigation. PRC-026 deals with non-tripping during stable power swings. You will see voltage and currents way out of whack during system temporarily or during something...
  5. HamburgerHelper

    ETAP and SKM: Bus count for packages

    I am looking at packages SKM and ETAP packages. They have you buy in at various maximum bus counts for a project. SKM has 50,100,300,1000,2000,5000, and 12,000. I am thinking both of them try to sucker you in into buying too much. What is the bus count you have found at large facility? They...
  6. HamburgerHelper

    Non-Profit Engineering Firm

    Has anyone heard of a non-profit engineering firm? In a very brief look, I saw that their are provisions for scientific organizations. I imagine that you could pay employees more if you had this designation by avoiding taxes...
  7. HamburgerHelper

    Manhattan Partial Blackout

    There turns every day with networked solutions and you don't have to try hard to find an example of something going wrong due to miswiring. ------------------------------------------------------------------------------------------ If you can't explain it to a six year old, you don't understand...
  8. HamburgerHelper

    Drying out moisture in EHV cables

    I have no experience with this but my gut tells me that it will be like a car that has been in an accident. Some things never be right and you'll be blamed if something happens even if it is just coincidental. I suppose it depends on what kind of a deal they give you and what kind of reliability...
  9. HamburgerHelper

    Magnitude of neutral current in distribution transformer

    It can be more than in each individual phase. Zero sequence harmonics on each will pass through the neutral. Neutrals are sometimes larger than the phase conductors for this reason. ------------------------------------------------------------------------------------------ If you can't...
  10. HamburgerHelper

    OverWorked/Bullied/Blackmailed

    I am always amazed at how much time we spend at work. Often more than most spend with their family or significant other. If someone did a Madlibs of a crummy job situation, people would just move on without a thought. I have a (girlfriend) who move (heaven and earth) for and all I get is...
  11. HamburgerHelper

    Manhattan Partial Blackout

    This is what I would bet it is. No one was providing oversight to the engineering because the utility was very short staffed or it was assumed the outside consultant would check their own work to make sure that it was always 100% correct. Problems like this accumulate and since faults are...
  12. HamburgerHelper

    3-winding transformer impedance

    I can't see the attachment but if you are rating something on a higher base, it's pu impedance will be higher as well. ------------------------------------------------------------------------------------------ If you can't explain it to a six year old, you don't understand it yourself.
  13. HamburgerHelper

    Transformer Phase Shift

    I really think you need just draw out the vectors and go through all the combination. There really aren't many and it is important to see how to get all the different possible combinations. I think there are four connections angles you can have. 30, 150, 270, 330. Here is a DYN11...
  14. HamburgerHelper

    Open Concept Offices

    I don't like open offices. It gets to be too loud. It is nice when you are new to something to be able to quickly ask a question but when you are up to speed, silence is better. ------------------------------------------------------------------------------------------ If you can't explain it...
  15. HamburgerHelper

    Earth pit?

    The IEEE Color books got transferred over to the DOT system and collected. One of the IEEE 3000 to 3007 books probably has what jghrist has posted, too. I would guess it would be IEEE 3003, Power Systems Grounding...
  16. HamburgerHelper

    Phasor rotation

    You can fix phase rotation but you still have to get the phase angles correct on the secondary side if you might be fed from multiple sources or swap over loads. Transformer connections must have the correct rotation and angles. Most utilities have a +/- 30 degree connection between the high...
  17. HamburgerHelper

    What is the single line to ground UTILITY fault current and X/R when only given the 3-phase info?

    ...and I am assuming Z0=0, which is assuming you are right up against the wye side of a delta wye transformer. Assume Z2 = Z1 and Z0=0 SLG = 3*V/(Z2+Z2+Z3) = 3*V/(Z1+Z1+0) = 3*V/(2*Z1) = 1.5*V/Z1 = 1.5*(Three_Phase_Fault)...
  18. HamburgerHelper

    What is the single line to ground UTILITY fault current and X/R when only given the 3-phase info?

    ...get the information from them but I think this could give you a ballpark range of what the most it could be. 3PhaseFault = V/Z1 SLGfault = 3*V/(Z1+Z2+Z0) = assuming Z2 = Z1 and Z0 = 0 = 1.5*V/Z1 ------------------------------------------------------------------------------------------...
  19. HamburgerHelper

    Higher Voltage vs Lower Voltage Safety

    There is complacency at lower voltages that can make them equally dangerous. You'll hear stories of electricians falling over after getting shocked with 120 v and not thinking it a big deal and not seaking medical attention. 120v is scary when your hand is locked onto a live wire and you can't...
  20. HamburgerHelper

    Transmission system overvoltages during major load throw-offs

    PJM sometimes mishaps transformed to circulate cars and bring the voltages lower during low loading condition. They have a paper on it. I suppose the cons of it would be that you are heating up the transformer, losing capacity, and moving taps...

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