On our Transformer LV side I have SC currents of up to 50kA. The transformers are typically 1MVA 3.3kv to .42kv. They were manufactured in the 1950 to early 1960 and have a %Z of 1.92.
The secondary tie CB are normally operated open. When close, the SC level goes up to approx. 100kA.
My...
davidbeach,
You replied to another thread with the same question but that thread was deleted and as such I was not able to read it. If you read the reply, please repeat your reply here if it is not too inconvenient for you.
Please attachment with all three SLD...
The final file - parallel transformer and motorshttp://files.engineering.com/getfile.aspx?folder=5c4a021e-e4df-4c1b-a6bc-88097d5e3e12&file=3-Bus_Network-Trxf&Mtr..jpg
Please see the other OL diagram attachhttp://files.engineering.com/getfile.aspx?folder=45be87aa-dc53-4480-a8c6-b8e7d59654de&file=2-Bus_Network-Single_Trxf..jpg
From the attach JPEG file with single transformer my understanding as it relates to calculating the relay 50/51 elements are as follows:
1) Determine max transformer FLA, NATURAL COOLING (55deg.C)1mva/ (1.73x3.3kv)=175A.
2) Select phase OC relay(51) pickup in the range 150-300% of transformer...
Hi All,
I just want to clearup an issue I have being pondering for a little while.
Lets say you have a relay with the Instantaneous set at, say, 12000A for a CB rated at 1600A. Is it a situation where the Inst. picks up 12KA or higher, or is it at some value below 12KA?
Thanks
Thanks guys for the help. A special thanks to Kiribanda for his/her suggestion that a closed switch was SC an impedance. Further checks revealed that was infact the case.
Hi All,
Being using ETAP 6.0 for a few years now and I just modeled a refinery with approx. 11 substation and a power generating plant. The problem i am having is whenever I try to run a SC or LF, it gives me this calculation error: "Calculation aborted due to superfluous branch connection". I...
