voltage added by a phase-shifted portion of zero-sequence current (see equation
) at
the location of the protection. The factor k = setting K
mag
. This type of polarization is
intended for use in applications where the zero sequence voltage can be too small to be
used as the polarizing quantity, and there is no zero sequence polarizing current
(transformer neutral current) available. The zero sequence voltage is “boosted” by a
portion of the measured line zero sequence current to form the polarizing quantity. This
method requires that a significant difference must exist in the magnitudes of the zero
sequence currents for close-up forward and reverse faults, that is, it is a requirement
that |V0| >> |k · I0| for reverse faults, otherwise there is a risk that reverse faults can be
seen as forward.
AngleRCA
0
0
V
k I e
-
+ × ×
EQUATION1638-ANSI V2 EN-US
(Equation 192)
The negative-sequence voltage polarization with negative-sequence current
compensation (-U2Comp) compares correspondingly I
2
with (see equation
similarly it must be ensured that |V
2
| >> |k · I
2
| for reverse faults.
AngleRCA
2
2
V
k I e
-
+ × ×
EQUATION1639-ANSI V2 EN-US
(Equation 193)
8.7
Mho impedance supervision logic ZSMGAPC
SEMOD153841-1 v3
8.7.1
Identification
GUID-030C086A-8301-481E-BA0A-6550A9C1482E v2
Function description
IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
Mho Impedance supervision logic
ZSMGAPC
-
-
8.7.2
Application
SEMOD154555-4 v3
The Mho impedance supervision logic (ZSMGAPC) includes features for fault
inception detection and high SIR detection. It also includes the functionality for loss of
potential logic as well as for the pilot channel blocking scheme.
One part of ZSMGAPC function identifies a loss of phase potential that is the result of
a long term (steady state) condition such as a blown fuse or an open voltage
1MRK 504 163-UUS A
Section 8
Impedance protection
Transformer protection RET670 2.2 ANSI
315
Application manual
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