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Anyone has any hint for me? I looked at the standard IEEE C57.12.91, but could not find a specific example for a Zig-Zag transformer.

I'm trying to calculate the X0/R0 ratio of a Zig Zag transformer. I got the following information: -Winding connection: Zig Zag -Short time neutral current: 3500 A 5 sec. -Continuous neutral current : 250 A -Voltage : 26.4 kV -Zero sequence impedance: 7.5 ohms/ph -No load losses: 1951 W -Load...

Thanks everyone for your answers. I seems that 2500 kVA threshold comes from the McGraw-Edison Distribution System Overcurrent Protection Workshop. However, I could not find the original document.

The IEEE 141-1993 states that in general, the transformer inrush current is approximately 8 to 12 times the transformer full-load current for a maximum period of 0.1 s. However, in the IEEE 242-2001 only mention 12 times the transformer FLC. I see frequently engineer using 8 times FLC as inrush...

Thank you very much everyone. I now understand better why the IEC 60287 and Neher-Mcgrath methods use the soil temperature at cable depth and not the ambient temperature.

Hi, This question has already been posted in two other threads, but the answers provided were not really helpful. In Neher-Mcgrath and IEC 60287, it is stated that the ambient temperature is the soil temperature at cable laying depth. As I understand it, those methods consider an isothermal...