ABB Relion 670 Series Technical Reference Manual page 251

1MRK505222-UUS C
Technical reference manual
(
b =
- ×
ang V I ZPP
AB AB
EQUATION1789-ANSI V1 EN
where
V
is the voltage vector difference between phases A and B
AB
EQUATION1790-ANSI
V1 EN
I
is the current vector difference between phases A and B
AB
EQUATION1791-ANSI
V1 EN
ZPP is the positive sequence impedance setting for phase-to-phase fault
V is the polarizing voltage
pol
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
( )
)
-
ang V
pol
Section 6
Impedance protection
(Equation 34)
245