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  1. Fuse4

    Coordination time interval for electronically-controlled reclosers

    I agree with protoslash, with the time of 150 ms, verify that opening mechanism is equal in both recloser and has the good opening speed conditions to avoid miscordination (low bateries produce slow opening conditions). In primary tests include the time of the relay and the mechanism and is a...
  2. Fuse4

    59N For Medium Voltage

    For earth fault both neutrals of the transformers YNyn should be conected to ground
  3. Fuse4

    Isolated neutral - Ungounded system - Earth fault calculation

    Dear all. I am reviewing this topic since time ago. Here the comments: 1. Obtain the Equivalent Circuit of the Ungrounded System: Is a series VLine, Zfault, C circuit VLine/V3 = Ifault *(Zfault + Xco/3) (Complex quantities) 2. For Bolted Fault (Zf = 0) The total capacitive charging current is...
  4. Fuse4

    ZCT setting in ungrounded systems

    For ungrounded systems with only 1 feeder is true that the ZCT (window transformer) do not see earth fault current because the current of the faulted phase is the sum of the other phases (opossite direction) and always the ZCT see zero amper. (IEEE papaer "Considerations for ground fault...
  5. Fuse4

    Is there any advantage to ungrounded wye wye power systems? Ungrounded Wye delta?

    For ground faults, the delta system has the same behaviour that wye system with isolated neutral (the low voltage side).
  6. Fuse4

    Titles in XY graphics Mathcad Prime

    Dear all I am triying write the title of an graphic and of the X and Y coordinates, if someone can give advice. Thanls.
  7. Fuse4

    Overcurrent Protection Coordination with Delta/wye Bank

    I agree with HamburgerHelper, perhaps, you can use the negative sequence overcurrent to the high transformer side protection. Check appendix II Faults on the secondary of a delta - wye transformer in paper "Negative-Sequence Overcurrent Element. Application and Coordination in Distribution...
  8. Fuse4

    Multiple Ground Faults on Isolated Ground systems of mixed voltages

    Dear Bloozntooz7868 In this Excellent book "Industrial Power System Grounding Design Handbook" by J.R. Dunki-Jacobs • F.J. Shields • Conrad St. Pierre, you can find about your question. Look the cover of the book in http://www.groundingdesignbook.com/ anf Fig. 12.2...
  9. Fuse4

    X/R Calculation or %X

    Jackreacher, was a mistake, thanks. You are with true. Here the values: Define: Vk" = 11 kV < 0° Sk" = SQRT(3)*Vk"*Ik" = 1.73*(11kV<0°)*(13,027kA<-86,24°)= 248,20MVA<-86,24° Zk" = Vk"*Vk"/Sk" = (Rk"+jXk")Ω= 0.488Ω<86.24°=(0.032+j0.486)Ω Rk" = 0.032 Ω Xk" = 0.886 Ω X/R = 15.216 %X =...
  10. Fuse4

    X/R Calculation or %X

    Define: Vk" = 11 kV < 0° Sk" = SQRT(3)*Vk"*Ik" = 1.73*(11kV<0°)*(13,027kA<-86,24°)= 248,20MVA<-86,24° Zk" = Vk"*Vk"/Sk" = (Rk"+jXk")Ω= 0.844Ω<86.24°=(0.055+j0.843)Ω Rk" = 0.055 Ω Xk" = 0.843 Ω X/R = 15.327 %X = (0.843 Ω / 0.844Ω)*100% = 99.882%
  11. Fuse4

    Modern Power System Protection Training Course

    Dear tctctraining You can apply for free webinars about protection systems too. Here some that I know "2014 Protective Relay School webinar series". I will thank if someone know others. http://www.abb.com/industries/ap/db0003db004333/557dde83db2055c7c1257acb00690105.aspx Regards,
  12. Fuse4

    Inrush Transformer

    Sorry Here the atttachment. http://files.engineering.com/getfile.aspx?folder=61a8d628-d36b-4e52-acb3-6e43edd9c759&file=Inrush_Transformer_220_kV.docx
  13. Fuse4

    Inrush Transformer

    Dear all I have a question about inrush power transformer waveform. When we connected to the system the new bank power transformer in 220 kV without loas we have the following record in the relay, we can see the frecuency es different in two times. I will thanks your comments.
  14. Fuse4

    Power Link - Selection and Ordering Data

    Dear Engineers I am looking about the "Selection and ordering data" of the Power Line Carrier Siemens brand equipments (Power Link - Transmission Power, ethernet port, remote management, teleprotection, others). I have two models and I do not know the details. I will thanks your answer...
  15. Fuse4

    open delta transformer

    The resistance depends of the transformers brand. In same time ago I saw a unit with a variable resistor. Here an example: Cahier technique n° 190 Ferroresonance schneider-electric.com...
  16. Fuse4

    High-Frecuency Earth Meter

    Dear jghrist Perhaps a tellurometer is a incorrect word of the equipment. In the Std IEEE 81 - 1983, numeral 12,6 says "High-Frequency Earth Resistance Meter" and suggests the measurement with a high - frequency which operates to 25 kHz. This standard indicates that document "High Frequency...
  17. Fuse4

    High-Frecuency Earth Meter

    Deear lume7006 and dpc Thanks for your answer, I am interested in the resistance to remote earth from each tower without disconect Ground Wires, I don't know if a a high frecuency tellurometer is the best option. thanks newly.
  18. Fuse4

    High-Frecuency Earth Meter

    Dear all For test system ground of the each power transmission towers all electrically interconnected by means of Ground Wires, is necesary use a high frecuency earth meter ?. I will thank your comments and brands of equipment if is possible.
  19. Fuse4

    5 kV Generator Grounding

    Dear all More standards: C62.92.3 Guide for the Application of Neutral Grounding in Electrical Utility Systems, Part III—Generator Auxiliary Systems C62.92.3 Guide for the Application of Neutral Grounding in Electrical Utility Systems Part II—Grounding of Synchronous Generator Systems

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