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Hello I'm a little confused by your writing. If you have setup the system to have a fault between b-c, then your parameters are: I[a] = 0 I[b] = - I[c] V[b] - V[c] = I[b]Z[f] If you take a fault between a-b, then your system parameters change: I[a] = - I[b] I[c] = 0 V[a] - V[b] = I[a]Z[f]...

Thank you all for the inputs. They've been a great help [smile] Short circuits, protection, arc flash assessment. That's what I know best :D

Hello I've learnt about PLC programming and want to learn about SCADA systems. I know a google search can yield a lot of results, however since most of my google results either lean towards: "Learn by making your own" or "buy our SCADA solutions" I haven't really learnt anything from that. My...

Hello I did a project on this back in 2017, although I fear I only passed this because our teacher and examinator forgot we were doing work on Ynd transformers over Dyn. The best I can give you is one reference, I would link you one that deals with this specifically, the problem is it's in...

Hello Desrod2 I only barely passed programming although this is mostly due to my illness becoming even worse during that time. I have considered learning PLC programming although I'm very confused with how to go about it. I'm also looking at other countries than just Canada (Ireland, Scotland...

Electrical Transmission and Distribution reference book has all the two-circuit transformer, two-circuit autotransformer, three-circuit transformer and three-circuit autotransformer; positive and zero sequence equivalent circuit. There's also derivation of some of them, but not all. Be warned...

In Denmark; Residential and some industrial installations use TT. TN is found industrial applications, it was more or less exclusively used in the place I was an intern at. IT is found in hospitals and ships, and other places where a 1st fault will not result in a fault clearing, until...

Hi moltenmetal Thank you very much for the response, I've broadened my horizon to look at other countries as well.

Hey all I apologize ahead of time if this is the wrong place to post this, I wasn't sure. Basically my situation is this: I live in Denmark and the industry is "screaming" for engineers, which is true if you have +5 years worth of experience, which I don't (got my degree in January 2019). I...

Two other good references, although they're based solely on differential protection and distance protection are the Gerhard Ziegler books: - Numerical Differential Protection - Numerical Distance Protection The differential book is as the title states, solely focused on differential protection...

What type of installation is it (can we get a circuit diagram)? If your installation is near the transformer on the secondary side then L-G should be the same as L-L-G, this is of course under the pretence that all the impedances are equal. However! Since both L-G and L-L-G are dependent on...

Thank you all for your inputs, they've been very helpful.

I'm going to a job interview next week and I have 3 questions. I know that differential protection of transmission lines (Mostly done as aerial lines in my country and still being expanded on) has (probably) been a common practice for the past few years due to it's fast sensing and reliability...

Hello I have a question regarding current transformer saturation during fault conditions as listed in the subject title. Some background: We have a 3-phase induction motor drawing 500A during full load. I've chosen some current transformers: 500:5, 5P5, 30VA. (Transformers will not saturate...

Thank you all for your inputs, they've been very helpful.

As magoo2 already pointed out. If you want help on the proofs you can try looking at the book symmetrical components (1933 by Westinghouse engineers C.F. Wagner and R.D. Evans), you can find it on scribd.

Hello I've recently been reading about current transformers and their application in differential protection. From what I can understand if you're protecting a star connection, you have to connect the current transformers in delta and vice versa. What I don't understand is why this is the...

The best I could find was a standard IEEE-575. (Although only valid for 5kV to 500kV cables). Researchgate has an article that wrote down some of the equations in the standard. Link That's about all I can help you with. If you need something more specific, let me know, although I'm probably...

I'm currently writing a thesis on the application of symmetrical components for line and motor protection. The only time I've ever seen If=E/ZE, was as an equation in a instructional manual for an installation tester. In that one ZE is the measured loop through a conductor and the PE...