Negative sequence current calculations 1

[PrebenJakobsen]

Hi
Does anyone know where to find a simple spreadsheet that can calculate negative sequence current from a set of 3phase currents?

I am preparing a test of a Siprotec 7UM62 with a Omicron CMC256 and Siemens doesent specify how to test the function.

If I e.g. injects 1.2pu on two phases and 0.8pu on the 3rd I want to calculate I2. With that value I can find the expected tripping time on the curves or by the formulas.

Best Regards
Preben Jakobsen

 

[sibeen]

Add the three vectors and divide by 3.

 

[GTstartup]

Or swap two test leads and It's all negative sequence

 

[electricpete]

Sum divided by 3 would be zero sequence.
lmgtfy...

http://en.wikipedia.org/wiki/Symmetrical_components

=====================================
(2B)+(2B)' ?

 

[sibeen]

Pete, I don't know why, but I somehow read it as zero sequence. *does face palm*

*cough* Rotate phase 2 (W, S, V or whatever you call it where you are) by 240 degrees, rotate phase 3 (B, T, W or whatever you call it where you are) by 120 degrees, add the vectors and divide by 3.
*cough*

 

[stevenal]

Why not inject single phase? Iphase=3I+=3I-=3I0, leaving the complex arithmetic out of your spreadsheet.

 

[PrebenJakobsen]

Thanks for the posts.

My relay has an instant trip function but also a time dependant function which i would like to test at different points.

I have found a page

http://www.relaytech.com/symcomp_calculator.htm

which can do the calculations, but a spreadsheet for quick calculations on site would be nice.

Best Regards
Preben Jakobsen

 

[ProtectionEngineer]

Try to use this ABC012.exe

 

[DTR2011]

the omicron has a "fault calculator" that can be used in ramping, sequencer and Quick CMC test modules. It does the math for you.
Use the help function to look up how to access it.

 

[7anoter4]

I did once my self a VB program, but now I'll try to send an Excell file onle in order to verify how it will look.

 

[JG2828]

I like this one from Beckwith. See the third tab.
Very powerful.. Just enter the magnitude and degrees you are looking for, click convert and it will tell you to input into the test set.

FYI if everything says #NAME and it doesn't work, see the instructions on the first tab to enable the "Analysis ToolPak"

 

[JG2828]

Sorry, its from Basler, not Beckwith.