Should we activate zero sequence current elimination in differential relays for a YnD11 power transformer with a zig-zag grounding transformer on the delta side and grounded on the star side ?
Hello,
I've been working on symetrical components of transformers. I found a paper in which there is a table shows the impedance values of a 275/132/33 kV autotransformer. Is this a correct representation of impedance values ? Since the unit is in PU, isn't it supposed to be the same impedance...
Recently, I got fault records from a relay to analyze it. But I don't understand the phasor diagram of the fault. The angle between Ib and Ic is 178. The angle between Vb and Vc is 118. Now is this a L-L or L-L-G fault ? I'm also putting the picture here.
There are cases in which star-delta step down transformer, with delta side grounded through zig zag grounding transformer, connected to the cable distribution network. When there is a phase to ground fault on a cable feeder , compensation occurs between the capacitive current of cables and...
I know star-star and star-delta transformers are used in utility systems as a step down transformer due to their low costs. But which one is best for a 420/33 kV transformer? What would be the advantages/ disadvantages of each?
