0A 0 T,0 N
V 3I (Z 3R )= × +
EQUATION2024-ANSI V1 EN-US (Equation 441)
OB 0 T ,0 N lineAB,0
V 3I (Z 3R Z )= × + +
EQUATION2025-ANSI V1 EN-US (Equation 442)
The residual power, measured by the sensitive ground fault protections in A and B will
be:
EQUATION2026-ANSI V1 EN-US (Equation 443)
EQUATION2027-ANSI V1 EN-US (Equation 444)
The residual power is a complex quantity. The protection will have a maximum
sensitivity in the characteristic angle RCA. The apparent residual power component in
the characteristic angle, measured by the protection, can be written:
0A,prot 0A 0 A
S 3V 3I cos= × × j
EQUATION2028-ANSI V1 EN-US (Equation 445)
0B,prot 0B 0 B
S 3V 3I cos= × × j
EQUATION2029-ANSI V1 EN-US (Equation 446)
The angles φ
A
and φ
B
are the phase angles between the residual current and the
residual voltage in the station compensated with the characteristic angle RCA.
The protection will use the power components in the characteristic angle direction for
measurement, and as base for the inverse time delay
.
The inverse time delay is defined as:
0 0
inv
0 0
TDSN (3I 3V cos (reference))
t
3I 3V cos (measured)
f
f
× × ×
=
×
EQUATION2069 V1 EN-US (Equation 447)
The function can be set Enabled/Disabled with the setting of Operation.
1MRK 504 163-UUS A Section 9
Current protection
Transformer protection RET670 2.2 ANSI 561
Application manual
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