Tek-Tips is the largest IT community on the Internet today!

Members share and learn making Tek-Tips Forums the best source of peer-reviewed technical information on the Internet!

Register Log in
  • Congratulations cowski on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!

Search results for query: *

  • Users: prc
  • Content: Threads
  • Order by date
  1. prc

    The floating star neutral to earth voltage in transformer.

    In a 131/11.5 kV three-phase Dyn Transformer, a balanced 10 kV was applied to the primary, with the secondary neutral floating. The voltages measured on the LV secondary were equal in all phases. The line to neutral voltages were 504 V, the line to earth voltages were 505 V, and the line to...
  2. prc

    Current transformers- over voltage on open circuiting secondary

    It is well known that open-circuiting the secondary circuit of CT while carrying primary current will create overvoltage on secondary terminals. But will this lead to violent failure of CT with explosion? Has anyone noticed CTs in service with open-circuited secondary terminals?
  3. prc

    Reading lamp

    I believe eng-tips do not have an illumination engineering forum, so I am posting this query here. What is the best lamp (eg LED) for the reading desk? What is the optimum lumen for comfortable reading?
  4. prc

    Books on Instrument Transformers

    I have compiled Instrument Transformer books published so far. May be of interest to some of you.https://files.engineering.com/getfile.aspx?folder=89382716-425a-46ba-b1fb-ac37d68d3a9a&file=2021-02-_Books_on_Instrument_Transformers.pdf
  5. prc

    Two Inventions of 1885 that changed the World

    https://www.linkedin.com/pulse/two-inventions-1885-changed-world-p-ramachandran
  6. prc

    Time delay from fault to breaker opening

    I have a query on protection. Request guidance from learned protection Gurus. Let us take a 400 or 220kV transformer. Imagine a flash over from the bottom tail of bushing to tank. The system fault current will go into the arc in oil. In such a case, how much time will it take for the incoming...
  7. prc

    Auto-Transformer with two line supply- voltage in open phase

    Let us consider a case of a 220/132/11kV auto-transformer with and without stabilizing delta tertiary winding. Secondary is not connected to grid. Transformer is 3phase 3 limbed core type with solidly grounded HV neutral. In case HV primary is fed with rated voltage, but with one line open (...
  8. prc

    Fault current flow in Generator winding

    Normally LV side of large Generator Transformers(GSU) are connected in delta and HV side in YN. It is claimed by some experts that this is done to avoid flow of zero sequence currents through generator stator windings during an LG fault on HV side lines of GSU. Why Generator windings cannot...
  9. prc

    Tap-Changers in Generator Transformers

    In my country Generator transformers are provided with DETC (de-energized Tap-changers). In case of transformers for thermal sets (50-800 MW) tap-changers with +- 10 % tap range(9 tap) were used to be there. Later this range was reduced to 5 tap with +- 5 % range as these tap-changers are never...
  10. prc

    Grounding point for CT secondary star neutral

    When star neutral point of CT secondary is formed in substations where this is to be grounded -at CT secondary box near to instrument transformer in the yard or at the panel in control room?
  11. prc

    Transformer Fire Protection

    Is it mandatory to provide fire protection for power transformers? What is the rule or limits of transformer ratings in various parts of the world? There are various types of fire protection available-Mulsifyre ( spraying with water actuated by thermal fire detecting sensors) Nitrogen...
  12. prc

    Standards Relevant to Transformers

    For many decades, I was maintaining a list of standards relevant to Transformers -for application, specification, manufacturing,testing and maintaining transformers. Attached please see the updated list. May be useful to some of...
  13. prc

    Solar Power Farms

    Last month in India a 2000 MW solar power farm was commissioned, said to be the largest in the world. This is in Karnataka state where Bangalore is located. Farm covers an area of 13,000 acres and the entire land was leased out from farmers. Farmers claim they get more income from lease rather...
  14. prc

    History of a great Power Transformer Factory

    GE's Transformer factory at Pittsfield had a great legacy. See the attached links. http://ethw.org/Archives:Transformers_at_Pittsfield,_part_1 http://ethw.org/Archives:Transformers_at_Pittsfield,_part_2 http://ethw.org/Archives:Transformers_at_Pittsfield,_part_3
  15. prc

    Neutral grounding of Large Motors

    Neutral of large Ac generators are grounded through Neutral grounding resistors to limit the zero sequence currents. How the neutral of motors is grounded? Same way or through inductors? If later is the case, reason for the same.
  16. prc

    Grounding of stabilizing Tertiary winding.

    Normally one corner of delta connected stabilizing tertiary winding is grounded in service or neutral grounding achieved through grounding transformers or star connected electromagnetic PTs connected to tertiary terminals. Latest IEC 60076-3 Insulation levels of Transformers proposes as below...
  17. prc

    Rated voltage of lightning Arresters

    When LAs are used on the delta tertiary of transformers 110% rated voltage arresters are used, being ungrounded system.So in a 33 kV tertiary, 45 kV LAs are used to get 36 kV continuous power frequency voltage withstand performance. If a delta/star transformer is fed from a star/star (132/33...
  18. prc

    Power Transfer in Transformer

    I have a query -How the power is transferred from the primary winding to secondary winding in a transformer? General answer is through electromagnetic field, electric to magnetic and then to electric. But how? Can we explain this clearly so even a layman can grasp.
  19. prc

    Hot oil filteration in transformers

    In some utilities, as annual routine, they conduct hot oil circulation in transformers in service ( may be for 3-4 days). Taking oil from bottom of transformer tank, circulate through a filter machine(with a shrouded electrical heater to raise oil temperature to 70C + vacuum chamber to remove...
  20. prc

    Neutral earthing in solar Transformers

    Three winding transformers are usually used for collecting the power from solar power inverters, popular connection being Delta/Star-star. The neutral of secondary stars is never earthed, many times it is not even brought out. In one case, it was inadvertently kept earthed and inverters started...

Part and Inventory Search

Back
Top