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Hi argotier, The CT was always installed in the transformer but it's data went lost, i only want to resetting the WTI or replace it if found faulty. After read your last reply, i suddenly understand that the CT ratio is good enough for resetting/replace the WTI. I actually haven't conduct any...

Thank you everyone for your reply. Hi argotier, I only can obtain the following info: Tx HV winding rated current: 525A (obtained from power Tx nameplate) HV WTI(winding temperature indicator) is of very old version type, no info of the CT current input can be obtained. Let said we obtained...

Thanks for reply. Sorry i think my question maybe misleading. I mean, let say the ratio is 500. So anyway that we can say that this CT is probably 1000/2A or probably 750/1.5A or...etc.? The transformer winding rated current is around 500Amp. ( but primary current of this unknown bushing CT...

thread238-415974 Hi, Reference to above thread. If we have an unknown CT (without nameplate data), do we have any method to determine its correct ratio? Let say we injecting 10A primary, and get 0.02A secondary on a bushing CT (installed inside a Transformer for winding temperature used)...

Hi Stevenal, I rethink your question. Ya, You are right, in order to use the method suggested by unclebob, we need to at least short out the HV terminal of A6 and YN, otherwise voltage drop across winding a2 to a1 will affect the ratio result. Am i thinking on the right way?

Hi Stevenal, We not carried out ratio test for this CT this time, only Ct excitation test only, so not able to see the actual result based on the suggestion above. Maybe next time i will come across again this type situation, so i still figuring/studying all the suggestion from yours all above.

Hi David, The said CT saturated around 53V when i carried out the excitation test. Like that, smaller voltage existed at CT primary side, hardly pushed any current through the TX. Thank you so much, you help clear my doubt.

Hi Stevenal, my mistake on the sketch drawing. Actually the YN terminal was connected to ground. I redraw as per attachment.https://files.engineering.com/getfile.aspx?folder=8ed491cd-e472-4182-8722-d637b888bdef&file=bushing_CT_Mag_Curve_1.jpg

Thank you all for spending time to reply this thread. I have a question regarding this bushing CT as following: When we carry out CT excitation test (Finding the magnetizing curve for CT), we inject secondary of CT, and keep CT primary side open. For the Bushing CT in this case, I able to do...

Thank you scottf for your info. Thanks for all who spent time to reply this thread.

Hello all. This is a nameplate of an air core reactor. Do your have idea what is the manufacturer in full name? I tried to google but not able to find any. The name is Equip Ele?????alta Tensa? LTDA, anybody have any idea...

Hello all, I am from IEC world. We have a 275/13.8 kV 3 phase transformer. Vector group is YNd1. There is a 4700/5A bushing CT installed at low voltage b phase. Attached is the detail of this Tx. As the bushing CT primary side is not accessible, I can think of two option (other than the...

Thank you DTR2011 and scottf for your valuable suggestion.

When we carry out polarity test or flick test for Current transformer and inductive voltage transformer, we can use a lantern battery to complete the test. When come to 132kV CVT (outdoor type,Trench TEVF138 ) , the lantern battery yield no result (due to the capacitor divider C1 and C2?)...

Thank you ScottyUK and Krisys. Hi Unclebo: Agreed with you, the doble test (power factor test) will give a awkward result if we not shorting the HV (or LV) bushing terminal together during the test because I had seen it personally when the power factor test was carried out with and without HV...

Thank you prc and Zogzog

Hello guys, thanks for your reply. I attached a document regarding the requirement of linking all the Tx HV bushing terminal, ie. L1 , L2 and L3 together during the insulation resistance test. Dear buzzp: I was using normal insulation resistance tester (kyoritsu 3123A) Dear Waross: I am checking...

Hi btrueblood, thank you very much!

Hello guys, i have a question on insulation resistance (IR) test. When we conducted IR test with 5kV DC on a 132kV GIS busduct which is already degassing and in vacuum stage (means SF6 gas removed, and is under vacuuming close to 1 mbar), the insulation resistance value for the busduct L1 phase...

Hello guys. I have a question and hope somebody can answer me as i tried google on this question, but seems not able to find an answer for it. The question is: When we conduct insulation resistance test on power transformer (let said vector group is Dyn11) high voltage winding against ground...