Negative sequence component rotation

Thread Starter

skyline977

Joined Jan 14, 2021
29
Hi,
I am reading some books trying to understand how physically they rotate in the same direction as the positive sequence components but in the reverse sequence. How can that even be. If a machine rotor under normal load conditions is rotating CCW with ABC sequence. How can the machine continue to rotate in CCW direction but with ACB sequence.

The book:


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My confusion is from the below page. How the phase sequence is reversed? As I understood from page#58 above as highlighted in red "The connections from a, b, c to a, c, b or vice versa can generally be made by completely interchanging phases b and c for both the equipment and the connections." Does this mean that they interchange the phases! it cannot be this. So, how phase sequence is reversed?
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Protective Relaying: Principles and Applications, Fourth Edition
By J. Lewis Blackburn
2014 by Taylor & Francis Group, LLC
International Standard Book Number-13: 978-1-4398-8812-4 (eBook - PDF)
 

Wolframore

Joined Jan 21, 2019
2,273
Phasors always rotate counterclockwise, this is due to multiplying by the imaginary i or j. i^2= -1. The naming conventions and the actual physical rotation doesn’t matter.
 

nsaspook

Joined Aug 27, 2009
8,376
https://na.eventscloud.com/file_uploads/9dbffc7085014d767e0e56b30eaaf405_RJA-PHASOR_DIAGRAMS_II.pdf
Phasor and Phase Rotation “Phasor” and “phase rotation” are two entirely different terms, although they almost look alike. AC phasors are always rotating counterclockwise at the system frequency. In contrast, phase rotation or phase sequence refers to the order in which the phasors occur as they rotate counterclockwise. The standard sequence today is a, b, c; A, B, C; 1, 2, 3; or in some areas R, S, T.
 
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