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  1. asymptote

    Why diode with lamp ?

    Hi Forum. Thanks for those constructive comments, all of which relavent but dont quite satisfy my curiosity. When and if I find a better reason I shall finalise this tread.
  2. asymptote

    Why diode with lamp ?

    Hi to all. The car is a current VW Golf. The diode is an original item being crimped into the plated steel lamp fixings. The light is in fact the boot/ trunk light mounted in the rear roof trim and illuminates above the parcel shelf. There is a requirement to add additional leds below shelf...
  3. asymptote

    Why diode with lamp ?

    The rear roof light in grandsons car has a diode connected in series with a 10watt filament lamp. As the is a 12 dc circuit I’m at a loss to see what duty this diode has. It is clearly forword biased as the lamp works, reversed bias = no light. Can someone offer an explanation please.
  4. asymptote

    MV Switch Fuse data plate

    Sorry the (after fuse : 1/2.5 kA ) Tk : 3 s not 1/25kA
  5. asymptote

    MV Switch Fuse data plate

    Hi Forum. Can any one offer an explanation of the following data taken from Ormazabal CMP-F 36kV switch fuse. "Ip/Ik ; 20/50kA (after fuse 1/25kA) tk ; 3 s"
  6. asymptote

    voltage transformer secondary grounding

    This is the normal configuration for metering and protection VT's in the UK
  7. asymptote

    Large motor earth fault

    At 11kV (6351volts) 150 amps of earth fault is going to leave it's mark if realy is a fault. How is the earth fault relay connected. Residual or balanced. Is the relay IDMT or instant. How is the source neutral/star point connected and how big is the network connected at the PCC?
  8. asymptote

    Electrical equipment life span?

    In the UK Utility, distribution equipment such as transformers, cables and switchgear was thought to have a economic life of 80 years. Motors are a different can of worms as the forum will no doubt tell you.
  9. asymptote

    POWER TRANSFORMER PEAK CURRENT

    As a post script to dpc's comment on typical inrush currents for 3 phase transformers of 10 x FLC as the accepted norm. I have recently been advised that air cooled 1.6MVA TX will have inrush of 15XFLC.
  10. asymptote

    Motor Vibration

    Forum. Thanks for your interest in this matter, I can now report that the site have resolved the problem which seems a combination of mechanical and structual issues. The cast iron pedistal was removed from the pump room floor, a new beding seal formed and the foundation mounting /fixing bolts...
  11. asymptote

    Motor Vibration

    stardelta. The motor was run at full volts in it's normal vertical mode but without pump load. Bearing acceleration given in first post. oftenlost. The machine was found vibrating and sent to test shop for inspection (eight ton motor 200 mile round trip)only to get healthy report. waross. The...
  12. asymptote

    Motor Vibration

    Very helpful comments there. Thanks.
  13. asymptote

    Motor Vibration

    Forum. This is a slow moving issue as plant availabilty constrains instant testing and feedback on the points you have all raised. However I will keep you up to date with progress. As a suplimentry question associated with this issue. I have been trying to obtain from the manufactures (LSE)of...
  14. asymptote

    Motor Vibration

    Mendit. I need to get further data to answer points you have raised as to type of bearings. As for the test run I have to assume it was at rated voltage.
  15. asymptote

    Motor Vibration

    edison123. I'm told that appart from a detailed rotor inspection the stator was cleaned/dusted, the machine re assembled and tested bolted down to a very stable test bay floor and yeilded "all pass" on vibration tests as given in first statement.
  16. asymptote

    Air Cooled vs Water Cooled

    The water jacket provides very effective sound attunuation which might be an advantage in some applications.
  17. asymptote

    Motor Vibration

    Mark. I have only seen the motor on load but have been told that the same vibration is there with the coupling broken so the source has to be the rotating mass of the rotor. However, the rotor has been examined in depth by the largest UK manufacture/repair shop and the complete machine(less...
  18. asymptote

    Motor Vibration

    electricpete. Thanks for the interest. I did state up front that it is squirrel cage rotor, not vfd and tri-slot is a variation of double cage rotor giving reduced start amps and increased start torque. Maximum power transfer is when Rotor R = Rotor XL. You can't play with R on a squirrel...
  19. asymptote

    Motor Vibration

    Hi Forum. Lots of very thought provoking ideas there. My role in this issue is as the protection engineer but sitting in on meeting the other day there were a lot of blank faces so I thought I would see what the world could contribute. To answer some of the questions raised in the forum, the...
  20. asymptote

    Motor Vibration

    Hi warross. I'm told it was bolted down to a test bed in the vertical (normal) position. I forgot to say in the first statement that it is a tri-slot rotor.

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