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  1. FacEngrPE

    Fiberglass Conduit

    Putting the cables in metal pipe, fiberglass duct, or plastic does nothing to the thermal resistance of the dirt. Duty cycle may be controlling as the dirt has a bunch of thermal inertia. Does Neher&McGrath address duty cycle?
  2. FacEngrPE

    Transmission Line Geometry and Impedance/Losses

    Interesting, Another difference between IEC and NEC worlds. Where FPelec describes towers with 5 phases, 1 circuit with unusual conductor arrangement. The article I cited above describes a line with 6 phases with 60 incremental degrees phase rotation. 5 phases brings to mind 5 conductors with...
  3. FacEngrPE

    Spain and Portugal power grid collapse

    Poll slipping occurs in rotating generators when displacement between rotor and stator magnetic fields does not generate enough torque to keep them in sync, the result is a very violent torque event, jumping to the next alignment that generates sufficient torque. Pole Slipping can't occur in a...
  4. FacEngrPE

    Spain and Portugal power grid collapse | Report Released

    Primary frequency control and the discussed loss of power factor control are closely related, Attached is a paper " Primary Frequency Response and Control of Power System Frequency Prepared for the Office of Electric Reliability Federal Energy Regulatory Commission Principal Author John...
  5. FacEngrPE

    Spain and Portugal power grid collapse | Report Released

    Inertia and VAR control are both necessary components of regulation. if the tariff values them appropriately they will be available when needed. Here they obviously were not valued appropriately. Will they be the next time they are needed?
  6. FacEngrPE

    Transmission Line Geometry and Impedance/Losses

    6 phase circuit on single tower So Far only a few installations. Reported to have some advantages in limited rights of way situations. Revisiting Six-phase Line Transmission Attached Performance Evaluation of Six-Phase Power Transmission Line With Limited Right-Of-Way
  7. FacEngrPE

    Spain and Portugal power grid collapse | Report Released

    Or convert the turbo generator sets into synchronous condensers https://www.eng-tips.com/threads/how-to-convert-generator-to-synchronous-condenser.464327/ On a steam turbine set. the turbine and the generator need to be disconnected from each other, and a pony motor added for startup. Control...
  8. FacEngrPE

    Spain and Portugal power grid collapse | Report Released

    Many of the major suppliers have offerings, all being marked as able to improve system stability when the conventional supply of inertia is retired. The difficulty is that in many places VARS are not values sufficiently that merchants are encouraged to connect offerings to the grid. That seems...
  9. FacEngrPE

    Two 250 VDC 1200A rectifiers feeding multiple crane rails - is it OK to put the outputs in parallel ?

    You should not need to care if the loads share equally, just that none of the rectifiers exceed their current ratings. Rectifiers have rather minimal ability to accept over loads. I did not see a current limiting circuit in the rectifier, so any limiting will be by the circuit resistance and...
  10. FacEngrPE

    Two 250 VDC 1200A rectifiers feeding multiple crane rails - is it OK to put the outputs in parallel ?

    The vendors statement is most likely literally correct. Do not expect the rectifiers to share load equally. The arrangement may be OK if the goal is automatic load shifting between rectifiers on loss of supply, or disconnection of a rectifier. Load shifting does not require load sharing, so...
  11. FacEngrPE

    FDC Sign Design Ordinance?

    See NFPA 170 Standard for Fire Safety and Emergency Symbols The sign in the OP post "Fire Department Automatic Sprinkler Connection, Siamese" Example https://www.mysafetysign.com/fire-exit-signs/nfpa-170-fire-signs/sku-s-5589 However an ordnance will trump a standard. Signs with the letters...
  12. FacEngrPE

    Deaerator Inspection Frequency

    EPRI Has published a number of good resource documents related to inspection and operation of deareators. I have attached Deaerator Tank Assessment Guideline Dec 2010. The National Board publishes System Design, Specifications, Operation, and Inspection of Deaerators Link This document contains...
  13. FacEngrPE

    North Korean Ship Fails/Capsizes at Launch in Front of Kim

    The structural member in all cases i am aware of that synchronizes the dolly or skid motion is the ship hull. The launch systems I am aware of are all specific to individual shipyards (or possibly design agencies). At the launch pivot point, the skid assembly can be subject to very high...
  14. FacEngrPE

    Newly opened road fails in Vietnam

    FF4P+HWP, Vĩnh Phú Đông, Phước Long, Bạc Liêu, Vietnam
  15. FacEngrPE

    Spain and Portugal power grid collapse

    This sounds a bit like blowing smoke IEEE 1547-2018 Clause 6.5.2.6: Voltage Phase Angle Changes Ride-Through
  16. FacEngrPE

    Spain and Portugal power grid collapse

    Back to the OP's subject. It happened here already. 2022 Odessa Texas Disturbance ERCOT Presentation September 13, 2022 This event shows that a very short event can create enough upset in a power system to trip it off line quickly - although in the Odessa Texas event the system recovered...
  17. FacEngrPE

    Spain and Portugal power grid collapse

    Starting to see some well thought out discussion with better technical content. Still not much. Spain-Portugal blackouts: what actually happened, and what can Iberia and Europe learn from it? The Conversation US, Inc. Published: May 2, 2025 No incentive for keeping reserve with inertia on...
  18. FacEngrPE

    FIU Bridge Update - New Bridge Has Broken Ground

    There is purpose to architect Louis Sullivan maxim, Form Follows Function. Ignoring this makes structures that are or become headaches. More here
  19. FacEngrPE

    Spain and Portugal power grid collapse

    A short trigger event resulting in voltage and current oscillation sounds like inertia may have been too low to stabilize the system. Possibly the trigger event excited some resonance in the bulk power system. Admitted the current evidence is thin and essentially hearsay. Yahoo News April 29...
  20. FacEngrPE

    FIU Bridge Update - New Bridge Has Broken Ground

    Quote from FIU webpage Link I would not read this to say that the pylons and cables provide much if any additional capacity to the bridge deck. The geometry does not appear to support the pylon handling that much bending force. The arrangement should redundantly support the pylons and cables.

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