Lecture-13 Parallel-Circuit Three Phase Lines. If two three phase circuits that are identical in construction and operating in parallel are so close together that coupling exists between them , the GMD method can be used to calculate the inductive and capacitive reactance of their equivalent circuit. Parallel circuit is shown for three phase lines on the same power.Although the line will probably be transposed, we obtained practical values for inductive and capacitive reactance if transposition is assumed. Conductors a and a’ are in parallel to compose phase a. Phase b and c are similar. We assume that a and a’ take the position of band b’ and then of c and c’ as theose conductor are rotated similarly in the transposition cycle. To calculate Deq the GMD method requires that we use Dpab , Dpbc , and Dpca the superscript indicates that these quantities are for parallel lines and where Dpab means the GMD between the conductors of phase a and those of phase b. For inductance calculation ds is replaced by Dps , is the geometric mean of the GMR values of the two conductors occupying first the position of a and a’ then the positions of b and b’ , and finally the position of c and c’. Because of the similarity between inductance and capacitance calculation , we can assume that the Dpsc foe capacitance and Dsp for inductance except that r is used instead of Ds of the individual conductor.
Lecture-13 Parallel-Circuit Three Phase Lines. If two three phase circuits that are identical in construction and operating in parallel are so close together that coupling exists between them , the GMD method can be used to calculate the inductive and capacitive reactance of their equivalent circuit. Parallel circuit is shown for three phase lines on the same power.Although the line will probably be transposed, we obtained practical values for inductive and capacitive reactance if transposition is assumed. Conductors a and a’ are in parallel to compose phase a. Phase b and c are similar. We assume that a and a’ take the position of band b’ and then of c and c’ as theose conductor are rotated similarly in the transposition cycle. To calculate Deq the GMD method requires that we use Dpab , Dpbc , and Dpca the superscript indicates that these quantities are for parallel lines and where Dpab means the GMD between the conductors of phase a and those of phase b. For inductance calculation ds is replaced by Dps , is the geometric mean of the GMR values of the two conductors occupying first the position of a and a’ then the positions of b and b’ , and finally the position of c and c’. Because of the similarity between inductance and capacitance calculation , we can assume that the Dpsc foe capacitance and Dsp for inductance except that r is used instead of Ds of the individual conductor.