ABB Relion 670 series - Page 251

( )
( )
AB AB pol
ang V I ZPP ang V b = - × -
EQUATION1789-ANSI V1 EN (Equation 34)
where
AB
V
EQUATION1790-ANSI
V1 EN
is the voltage vector difference between phases A and B
AB
I
EQUATION1791-ANSI
V1 EN
is the current vector difference between phases A and B
ZPP is the positive sequence impedance setting for phase-to-phase fault
V
pol
is the polarizing voltage
The polarized voltage consists of 100% memorized positive sequence voltage (VAB
for phase A to B fault). The memorized voltage will prevent collapse of the mho circle
for close in faults.
Operation occurs if 90≤β≤270
1MRK505222-UUS C Section 6
Impedance protection
245
Technical reference manual