As already mentioned, the US follows a Yd1 generator step-up transformer + Dy1 distribution transformer at the consumer end. IEC world follows Yd11 + Dy11 transformers. This is just a practice with no other issues. The voltage vector at the generator and the consumer will be in the same...
If you are loading a ZNyn transformer with a single-phase load, a stabilising tertiary is a must. Please see the attached link for details. ( last sections)
How do Zig-Zag Earthing Transformers work? - Applications - Confluence (atlassian.net)
https://rhconsult.tiny.us/2aew4ypn
The CT ratio depends on the type of WTI you are using. A popular brand has a secondary rating of 2 A. The transformer manufacturer has taken the rated current of the winding as the primary current of CT. It is not necessary, and typically, a higher CT ratio is used. The same CT is used for all...
Yes. You can have two secondary windings with equal percentage impedances. In India, we have several 315 and 400 kV transformers with 400/33-33 kV YNynyn units at Solar firms. Some of them have 5-limbed core construction without a stabilising delta winding,
In 2021, the Central Electricity...
1) Transformer overloading standards have changed significantly during the past 30 years. The relevant standards today are IEC 60076-7 ed2.0-2017 & IEEE C57.91-2011 for oil-filled transformers and IEC 60076-12-2008 & C57.96-2013 for dry-type transformers.
2) Manufacturers design transformers for...
Cucky, as someone who has designed large power transformers according to IEC and IEEE standards for more than half a century, let me confirm that I was making the same cooling circuit regardless of the standard. The temperature rises (oil/winding/ hotspot ) are the same in both standards...
cuky, as per my under standing, the temperature rise difference between IEC and IEEE is only 2C. The reference ambient temperatures are same. IEC 20 C is the yearly average and not stipulated in IEEE.
As per IEC60076-2, the maximum permissible winding hot spot temperature rise is 78 C, over a...
Let me disagree.
IEC specifies
Temperature rises based on max ambient air temp of 40C, monthly average of 30C and annual average of 20C. In case any one or more of the parameters differs from above, temperature rises can be modified as specified in IEC std clause 6.3.2 and table 2.
As per...
Yes, you can use FR-3 at that rating. In India, we have transformers with 315 MVA 420 kV rating and FR-3 filling. But what advantage are you expecting with such oils in such large ratings?
