Generator Negative Sequence Protection

[WattsNew]

Does any one know how to calculate generator I2^2 t curve for coordination purposes?

I know that K varies between 2 - 40 and I2 is percent of stator FLA. What percent of FLA is used to draw the curve?

Hope the question makes sense.

Thanks in advance

 

[alehman]

Typically the manufacturer specifies the value for K. (30 is common for cylendrical rotor machines). The curve is drawn for t = K/I2^2. I2 is per unit of nameplate current. I don't know if that answers your question or not.

 

[busbar]

The ability of a generator to accommodate unbalanced currents is specified by ANSI C50.12 and ANSI C50.13 in terms of negative-sequence current (I2). IEEE C37.102 specifies the continuous I2 capability of a generator and the short time capability of a generator, specified in terms I2[sup]2[/sup]t and defined in a dual-slope relationship plotted against generator MVA.

 

[jbartos]

Suggestion: Visit

http://pm.geindustrial.com/FAQ/Documents/SGC/GER-3181.pdf

http://www.abbus.com/abbrelays/pdf/100/41_178s.pdf

for
etc. for more info
I2^2xt may be given or measured.