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  1. Fischstabchen

    System Inertia and Synchronous Inertia

    Cranky, It doesn't operate faster. It operates instantly just due to physics. There is no lag. It is just energy put into or taken out of tons of spinning metal. The response after like 15 seconds isn't inertial but of governor valves opening up to pass more steam to increase generation...
  2. Fischstabchen

    System Inertia and Synchronous Inertia

    System inertia I believe shouldn't be looked at as providing fault current because fault current is very reactive. I think the best way to think about system inertia is that it is conceptually something that provides or stores energy instantly when there is a difference between generation and...
  3. Fischstabchen

    High Resistance Grounding vs Ungrounded LV systems

    High resistance grounding gets you many of the benefits of ungrounded systems without all the draw back. You have low fault current, can maintain operations, easier fault location, and all without having to insulate the system for transient overvoltages.
  4. Fischstabchen

    Changing current during a fault and overcurrent relays

    Yeah, that is what I was expecting. It makes moving on the time overcurrent charts a little bit more complicated than sliding left and right.
  5. Fischstabchen

    Changing current during a fault and overcurrent relays

    How do microprocessor relays time their overcurrent elements when the fault current changes during the fault?
  6. Fischstabchen

    Multiple Relays Sharing Same CT

    Modern microprocessor relays pass the current over a very small impedance and measure the voltage. The relay can be unenergized and current is still going to flow through it provided its input limits were never exceeded, which I have never heard of happening.
  7. Fischstabchen

    Expanding Substation Grounding System

    Maybe, a better question to ask would be "how comfortable would you be if you were brought into court due to field tech. being killed due to your ground grid design being non-compliant with the requirements set forth in IEEE-80?"
  8. Fischstabchen

    Supplying Residential Load from an Industrial Substation

    I think this is more of a question of not can you but should you. The part that would concern me is that for a facility to have its own substation, it has to have a pretty involved process to justify the expense. Does an industrial facility want to deal with a third party who can impact their...
  9. Fischstabchen

    Open CT secondary causing high impedance in primary?

    Stevenal, I don't think the open circuit voltage can be transferred back the primary just due to the fact that there is no current flowing on the secondary side. If the impedance was reflected, there would have to be a voltage drop due to the secondary on the primary side. The only thing that...
  10. Fischstabchen

    Open CT secondary causing high impedance in primary?

    No, a CT can't do this because it would saturate almost instantly. It would take hardly any current to magnetize the open CTs core. Once it is saturated, it is just a series inductance. Current splits on ring busses and whatever take very little extra impedance to path weirdly.
  11. Fischstabchen

    Sychronization of Sources from different Utilities

    Waross, Power from two separate utilities in the same grid won't necessarily inherently be synchronized.
  12. Fischstabchen

    Short circuit ampacity of ACSR wire

    It sounds like you might want to review how the conductor based on ambient temp and wind or get a system to monitor the dynamic loading of the line. These are sag detectors or things like optical temperature sensors.
  13. Fischstabchen

    NERC reporting requirements

    Are you a registered entity or should be registered? Your question is vague but you only have responsibilities if you are a registered entity.
  14. Fischstabchen

    Why is high voltage better for power transmission than high current?

    Lionel, You are overlooking the fact of how much vars plays a role in maintaining voltage. The voltage drop over an individual element may be I*Z but the amount of vars consumed by that segment is I^2*X. For that reason, in my opinion, when you double the voltage you reduced your real losses...
  15. Fischstabchen

    86 relay current draw?

    Buy a new lockout. The relay is not meant to see DC for long periods for through the coil. Whatever process you have is more expensive than than another relay. If smoke comes out of anything, you replace it.
  16. Fischstabchen

    Is it possible for un-proper sync cause differential trip on Generator

    Hoxton, Read what I wrote. The previous poster posted that the greatest mechanical stress is 90 degrees and I said contingencies will swing a generator past 90 degrees sometimes. You are not asynchronous until you go past 180 degrees.
  17. Fischstabchen

    Is it possible for un-proper sync cause differential trip on Generator

    You are going to see full torque one way and then full torque the other way as it oscillate between motoring and generating. Some contingencies put the angular difference between the generator and the system past 90 degrees, briefly. The generators are built for it. Large ones at least. If a...
  18. Fischstabchen

    Is it possible for un-proper sync cause differential trip on Generator

    FacEngrEE, The Mohave subsynchronous event threw parts from the system out of the building into their retention pound. It is no joke when power from the grid starts driving the generator. When stuff becomes asynchronous, it oscillates torques between motoring and generating quickly until...
  19. Fischstabchen

    Inertia - Synchronous Generators Vs Renewables

    Bacon4life, You could have a magnetic coupling and avoid seals. There are manufactures of magnetic gear boxes for wind turbines.

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