Protection Engineering Basics and Schemes Protection Engineering | Page 34
Now back to Eq ( 1 );
I b1 = I 1
and
I b2 = I 2
I r1 = I 1
and
I r2 = I 2
= I 0 + I 1 + I 2 + I 0 + a 2 I 1 + aI 2 + I 0 + aI 1 + a 2 I 2 = 3I 0 + I 1 ( 1 + a 2 + a ) + I 2 ( 1 + a + a 2 ) = 3I 0 = I n = I e = 0 − − − − − When system balance This zero sequence current is replicated by CBCT and below conditions tells the story
If I e = 0 Then there is no operation , let suppose we have EFI , then EFI will not show any indication
If I e ≠ 0 Then EFI operated , and there will be fault indication
1.1.12 Multicore and Multi Ratio CT : CT is divided in two types in terms of secondary winding .