Question

which wire contain only positive current and why​

Answer 1

$\huge\sf{\underline{\underline{➪Aɴsᴡᴇʀ \: :-}}}$

For a balanced system in the positive phase sequence, Ib = a2Ia; Ic = aIa. where a is the 120 degree operator (1<120)

I0 = 1/3(Ia + Ib + Ic) = 1/3(Ia + a2Ia + aIa) = 1/3Ia (1+ a + a2) = 0 . Since 1 + a + a2 = 0

I2 = 1/3(Ia + a2Ib + aIc) = 1/3(Ia + a4Ia + a2Ia) = 1/3Ia (1+ a + a2) = 0 .

Since

1 + a + a2 = 0 and a4 = a, & a3 = 1

I1 = 1/3(Ia + aIb + a2Ic) = 1/3(Ia + a3Ia + a3Ia) = 1/3Ia (1+ 1 + 1) = Ia .

Since a3 = 1

Thus, the only non-zero component of a balanced sets of currents or voltages in the positive phase sequence (i.e balanced 3-phase system) is the positive sequence component.

❥︎ɪᴛᴢDᴀᴋsʜ☃️☃️