Thanks for great answer. This might be slightly off topic but how does relay sense the zero sequence current for an external fault ? Does relay always calculate the symmetrical components?
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...
Hello, sorry for late reply. I'm sharing the oscillographic records here. This is a cable + OHL line. The line is three terminal line but protected from only two terminals with cable differential relay. Because there is no generation on the third terminal. So the current flows to the third...
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'm not sure what kind of specific information you request but It will be a step-down transformer connected to distribution network. HV and LV sides will be both grounded. Zigzag Grounding transformer will be used for the delta connection.
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?
