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  1. 144x

    Equilibrium temperature of a metallic bar

    Is there an example or guide or standard that has the formula that you can guide me to?
  2. 144x

    Equilibrium temperature of a metallic bar

    Hi, If a metallic bar is continuously heated by a heater, how the final temperature of the metallic bar can be calculated? I'm looking for some formula's to do manual calculations without resorting to sophisticated softwares. Metallic bar is not enclosed and on one side is in touch with a...
  3. 144x

    Medium Voltage switchgear Cable connection

    Like the attached sketch. Instead of two panels, both incoming and outgoing cables terminate in the same panel. have you seen such a case?
  4. 144x

    Medium Voltage switchgear Cable connection

    Hi, Imagine an MV switchgear is going to bypass an isolated gap in a busbar/conductor, etc. I want to know if anyone has seen an MV cubicle design where both incoming and outgoing cables to both sides of the gap terminate in the same MV cubicle. Is that at all possible? is there any standard...
  5. 144x

    Trip coil supervision relay 7PG17

    how much do you need it to be? what problem has it caused?
  6. 144x

    Current Transformer Turns Ratio and current ratio

    you are comparing CT's made and measured according to two different standards. one BS and the other IEC. X is the old standard. I think you better stick with the new one PX.
  7. 144x

    mv/A/m - Voltage drop

    if you have access to AS/NZS 3008.1.2 read it. if not you can read this https://www.nexans.co.nz/NewZealand/2013/Power%20Cable%20Catalogue%20Full%20version%202012.pdf which basically explains the assumptions in that standard. if not this page also explains how to include the PF in your tabulated...
  8. 144x

    mv/A/m - Voltage drop

    The "I" is different in those formulas
  9. 144x

    3 pole MCCB vs 4 pole MCCB

    Here is a case where using 4 pole breaker may prevent mal-tripping in other feedershttp://files.engineering.com/getfile.aspx?folder=165e8c38-a77b-4e9a-9244-158dcce1e72c&file=LV_switchgear.pdf
  10. 144x

    Circuit breaker close permissive

    I don't think you will find any standard that specifically mentions that signal. these are developed based on years of experience, trial and error and safe operation of the switchgear and is different for each industry. you should have years of experience to understand the need for the signal...
  11. 144x

    Protection of Air Core Dry type Reactors connected to a Transmission Line

    you can find the answer to your questions in the following references: 1- TECHNICAL BROCHURE Title: Protection, Monitoring and Control of Shunt Reactors-CIGRE WG B5.37 2- C37.109-2006 - IEEE Guide for the Protection of Shunt Reactors 3- IEEE Guide for Automatic Reclosing of Circuit Breakers...
  12. 144x

    power transformer sizing

    Thank you prc, if there is any limitation or requirement to be considered on the design of inverter transformers arising from irradiation variable or cyclic heating and cooling shouldn't these be mirrored or considered on the collector transformers as well ?
  13. 144x

    power transformer sizing

    thanks prc, is "IEEE C57.159-2016 – IEEE Guide on Transformers for Application in Distributed Photovoltaic (DPV) Power Generation Systems" is applicable for such large transformers also? I do not have the standard though.
  14. 144x

    power transformer sizing

    Thanks waross, let's assume there is no voltage drop as it is injecting power to the grid.
  15. 144x

    power transformer sizing

    Hi, my question is what happens if a power transformer is loaded most of the time close to half its full capacity and only for a very short period close to its full capacity. this happens in a design where a solar farm is going to be connected to grid (230 kV). should any special design be...
  16. 144x

    choosing the transformer vector group

    thanx for the responses .can you give any references for study? surely a drawing would help to understand the problem
  17. 144x

    choosing the transformer vector group

    let's assume that we can protect each transformer considering all the known rules of protection including zero sequence elimination on the side that is the source of it. unless you mean causing trouble for the part of network that is existing I don't think that protection of the new transformer...
  18. 144x

    choosing the transformer vector group

    you mean all the problems are evident? just kidding .but network owner is reluctant to accept this vector group even though the industrial complex is radial
  19. 144x

    choosing the transformer vector group

    Hi, all the transformers in a subtransmission network are Dyn11, in another part of the network a transformer with the vector group of YNd1 is going to be used for an industrial complex .there is no chance of paralleling of transformers but the primary of them are all connected in a ring of 132...
  20. 144x

    Earth pit

    thanx for the response,but what is going to be checked ,I have seen substations that do not have earth pit,I have seen substations that have their buried mesh coupled to the lightning protection (shield) through disconnecting link in the earth pit.but I do not understand what is the purpose of...

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