Negative sequence (Symmetrical component)

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To find the negative sequence current (I2) when given phase currents Ia, Ib, and Ic in a balanced load scenario, symmetrical components can be utilized. In an unbalanced distribution system, such as the example provided (Ia= 85 A, Ib= 92 A, Ic= 90 A), the angles are known relative to each other, allowing for the calculation of I2. The discussion emphasizes the importance of understanding the system's imbalance to accurately detect low fault currents. The user seeks to set the I2 pickup for fault detection purposes. Overall, the symmetrical transformation method is key to determining the negative sequence current in this context.
sarayut
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I'd like to know how do i find I2 (Negative sequence current) if I know Ia, Ib and Ic but don't know angle (in normal system_not fault)? My system's 3 phases 3 wires.
 
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You need to specify what you mean by "normal system_not fault"?

Is the load balanced? If so, you know the angles relative to each other. You can then use the symmetrical transformation to find if there is a negative sequence current.

http://en.wikipedia.org/wiki/Symmetrical_components
 
Thank you very much for answer!, "Normal system_not fault" mean imbalance situation in distribution system. For example Ia= 85 A, Ib= 92 A and Ic= 90 A. I'd like to know I2 for set the I2 pick up to detect low fault current.
 

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