Positive, Negative and Zero Sequence Current

Thread Starter


Joined Jan 4, 2009

Can someone help me understand positive, negative and zero sequence current? Can these be observed in real life or are they just mathematical means of observing current in a 3 phase system?
At a basic level I understand that the positive sequence is when the currents are moving clockwise direction with reference to one of the phases.
Negative sequence moving anti clockwise with reference to a phase.
Zero sequence all three phases are in phase.

What do these mean in practical terms? How can current waveforms which inherently move in positive phase sequence due to their generation at the source suddenly be in phase or negative phase?

In particular trying to understand regarding fault currents and how this poses an additional wide area of fault types regarding +,- and 0 sequence impedance which makes no sense to me.

Any help will be much appreciated.