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  1. waross

    Earthing of neutral on single phase transformer

    If I understand the question: Capacitive coupling may develop a very high common mode voltage on the secondary winding. It depends. First principles: Two insulated conducting objects, insulated from and separated from ground. Depending on the relative positions of the windings and the nearest...
  2. waross

    VFD(VSD) on sluice gates

    Lots of A-1 sauce. grin
  3. waross

    VFD(VSD) on sluice gates

    You probably know this Casey, but I will throw it out for others. The best motor for the high starting torque demand of a spillgate would ne a design "D" motor, but I don't think that design "D"motors are an off the shelf item. I see than on shears,and punch presses but they are part of the...
  4. waross

    Helicopter crash Hudson River

    The sequence given By Juan Brown, supported by photos; 1: Abrupt increase in altitude. 2: Loss of tail Boom 3: Loss of rotors, roof and transmission. If the jump in altitude was overcompensated for with less collective this could have triggered a boom strike. The boom failed at the rivets; Well...
  5. waross

    Helicopter crash Hudson River

    I hate to be kicking a dead horse, but I would like to see boom strike definitively ruled out. Juan Brown states that the boom broke at a row of rivets. Fair enough. But a strike behind the row of rivets may have caused the boom to break at a weak spot, that is at the row of rivets. Juan Brown...
  6. waross

    Electromagnet manipulating neodymium

    Or you could rewind your electromagnet with a heavier gauge conductor.
  7. waross

    Short circuit fault condition KA

    Note that the actual, first cycle, fault current may approach 2.8 times the calculated Available Short Circuit current. The exact value depends on the X:R ratio of the transformer and the point-on-wave of switching. When switchgear is rated for ASCC, this is taken into account.
  8. waross

    Should these thermocouples be free to rotate or not?

    If you want the thermo-couple to rotate, you should check the muffler bearings.
  9. waross

    Roller Coaster Design Challenge

    That's it. Thanks Dave.
  10. waross

    Roller Coaster Design Challenge

    In the video that I posted, a number of objects of differing mass were shot horizontally at varying speeds. The velocity was gauged by the horizontal distance the object travelled before it dropped to the floor. First demonstration: The mass did not affect the horizontal distance to fall to the...
  11. waross

    Roller Coaster Design Challenge

    I had to wonder; Each marble has the same Ft:lb of energy, so should not the exit speeds be equal regardless of the transit time? This video on exit speeds is interesting. Exit speeds
  12. waross

    BART FUBAR

    Did they add new rolling stock? System wide shutdowns were once a feature of Vancouver's Sky Train system each time new rolling stock was added.
  13. waross

    Clearwater condo evacuated

    Looks like Central American concrete. That is, a lot too great a slump to make placement easier. The excess water eventually migrates out, leaving the concrete porous. That allows moisture to ingress and corrode the re-bars. When iron converts to iron oxide, the volume increases, in some cases...
  14. waross

    Short circuit fault condition KA

    The ASCC, Available Short Circuit Current is the rated full load current divided by the transformer percent impedance voltage. You do the math: A 1000 KVA transformer; what is the rated secondary current at 440Volts and at 6.6kVolts?
  15. waross

    solenoid contactor plate material

    Expect solenoid failure with that use. Let the pump run and pulse with valves.
  16. waross

    Heat treatment machine power supply issue

    Nowhere has frequency been mentioned. A 470-575Volt machine intended for 60 Hz may not survive 480 Volts at 50 Hz.
  17. waross

    Query on Transformer markings

    0.42kV Taps: 0.42kV +2.5% 0.42kV + 2.5% + 2.5% (+ 5%) 0.42kV - 2.5% 0.42kV - 2.5% - 2.5% (- 5%)
  18. waross

    Stacking an object

    The definitive answer? IT DEPENDS!
  19. waross

    Maximum Temperature Rise for Fused Disconnect

    Damm. I need more coffee in my fiber.
  20. waross

    Maximum Temperature Rise for Fused Disconnect

    Yes David; The voltage drop from the knife blade to the incoming lug and from the knife blade to the outgoing lug. Each switch will have 6 points of measurement. Look for outliers. The test is done CAREFULLY with the switch closed and under load.

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