Recent content by elenapredescu

Thank you. I know that the standards are copyrighted but I have only ANSI C57.93-1995 and the table 5, that you mentioned, is missing. Maybe you reffer to C57.93-2007. This is the reason for asking you to give me only the table 5. Are you so kind to help me giving only table 5?

Sorry for writing three times but my intenet is not working properly.

Are you so kind to give me the table 5? Thank you.

Are you so kind to give me the table 5? I'll appreciate your kindness. Thank you.

Are you so kind to give me table 5? I'll apreciate your answer. Thanks.

I need informtion regarding the time and sequency for power transformer, 150 MVA 220 kV, energizing. I read about keeping the transformer about 72 hours no load before energizing. Is there some standards about this subject?

I suggest to use the rated power of 44/55 MVA, ONAN/ONAF. For ONAN the rated power is up to 80%.

Is anyone who can indicate me the level of induce voltage for power transformer which have to be tested according to GOST. Is it possible accoring to GOST that the level of induced voltage, on LV side, to be bigger than 2xUn? What is the number of GOST which give this indication.

Thanks! I already put ZnO elements on the tapped windings. I tried to get another solution that I didn't know.

Thank you all who have helped me.

Thank you! The transformer is 50 MVA; 132 kV star connection; off load tap changer is provided on the neutral +/-10%. During the impulse test on HV (BIL 550 kV) on the tapped windings apear more than 950 kV. The transformer is already manufactured and I ask for a solution without any changes...

No, I didn't talk about the OLTC protection. The tapped windings need, maybe, some arresters to protect against overvoltage but the transformer is already manufactured and it is not enought place inside of the tank. Thank you for your support.

For power transformer with no load tap changer +/- 10% of HV voltage, liniar; the value of overvoltage which apear on tapped winding is too high. What kind a protection for tapped windings it is necessary to use?

Hi, thank you for helping me. The tertiary windings, in this project, is required only for suppression of harmonics. The two terminals are brought out. The single protection that I used is CT for 50N (technical spec ask for).I hope I'll solve the problem after I'll disscus with the customer in...

Thank you. The project is for Kosovo.