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generally faults are of symmentrical and unsymmentrical faults that occur in majorly occurs in transmission lines........ the fault in electrical transmission line which give rise to symmetrical fault current is called symmetric fault. e.g; L-L-L-G fault.
if they are in low values then system is said to be "protected" ....
In order to avoid those NEUTRAL SHOULD GROUND with resistor or reactor etc,,,,,,,,...........
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Why do weprefer to analysis unsymmtrical faults by symmtrical components methods?
Because symmetrical components can represent an asymmetrical fault. That is, a phasor diagram with three different values of fault current and different displacement angles, can be represented by three symmetrical phasor diagrams: one with a positive phase sequence, the second with a negative phase sequence, and the third with each current in phase with each other. This is a very complicated subject and you are advised to seek a book on the subject, or research the topic online.
Use of symmetrical component in fault studies?
Symmetrical components are used to model faults on unbalanced high-voltage transmission/distribution systems, in order to predict the magnitude of fault currents resulting from various types of short-circuit fault, so that appropriate settings can then be applied to protective systems.The basic principle behind the method of symmetrical components is that any unbalanced three-phase phasor diagram can be represented by three balanced phasor diagrams, called 'symmetrical components', termed:positive phase-sequence diagram (displaced by 120o)negative phase-sequence diagram (displaced by 120o)zero phase-sequence diagram (in phase)This enables the electrical system to be represented by three sets of balanced phasor diagrams, rather than by a (terribly complicated!) unbalanced phasor diagram. This, in turn, allows the line fault impedances to be calculated relatively simply -these are represented by Z1, Z2, and Z0 -where Z0 represents an impedance path associated with earth faults.Further explanation of this topic is well beyond the scope of this answer, and an appropriate textbook should be consulted.
What is zero sequence currents?
Zero sequence is part of symmetrical components; it's a way of looking at three phase power that simplifies the math involved. In general zero sequence current is synonymous with ground fault current.
Is a sine wave a symmetrical waveform?
Since a sine wave is described by the trigonometric sin(x) function, which is symmetrical, the sine wave is also symmetrical, unless there is a DC bias, in which case it is not. (It depends on your definition of symmetry)
What is symmetric multiprogramming?
Where it has to do with symmetrical shapes and there equations.
