Correct Method for calculatiing Protection Relay settings

[DLoog]

What is the correct method for calculating protection relay setting for Overcurrent & Earth Fault relay.
This relay will protect a 11kV feeder, supplying
a 11kV/433V,2.0MVA transformer.

 

[wbd]

That's a pretty broad question. What you need to do is do a short circuit study. Then you can look at the fault currents and see where the relay has to be set so that the cable and transformer damage curves aren't exceeded. You also have to look at coordination with other protective devices such as fuses, circuit breakers, etc.

 

[SphincterBoy]

The best ways I've found (over the years) are to:

1. Attend classes offered by: Schweitzer Engineering Labs
and/or Cooper Power Systems. You will have to attend
these (week long) classes at their facilities.
This is the best way. Hotel, meals, and travel
expenses are extra.

2. Purchase one of several books, mostly written by
Blackburn, most notebly: "Applied Protective Relaying"
which can be obtained from: ABB Power T&D
1021 Main Campus Drive
Raleigh, NC 27606
voice: (919)856-3806
1992 cost: $85.00

Blackburn wrote a more recent book (prior to his demise
in 1997) which I think is the best. It has many
examples, and is much simpler than the former.
You can purhase this book from Amazon. I think the book
is entitled "Principles of Protective Relaying".
Cost: $90.00

3. Download the .PDF files of the GE manual "The Art
and Science of Protective Relaying" by Mason. One of
the other threads in this forum had the download link.

As a prequisite, you should thoroughly understand Symmetrical Components as well as basic power system fault analysis.