ABB RELION 650 Series Applications Manual page 164

Section 8
Current protection
=
3I
0
2 Z
EQUATION1948 V1 EN-US
Where
U
phase
Z
1
Z
0
R
f
The residual voltages in stations A and B can be written:
=
U
0 A
EQUATION1949 V1 EN-US
=
U
OB
EQUATION1950 V1 EN-US
The residual power, measured by the sensitive earth fault protections in A and B will be:
=
S 3U
0 A
EQUATION1951 V1 EN-US
=
S 3U
0 B
EQUATION1952 V1 EN-US
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:
S
0 A ,prot
EQUATION1953 V1 EN-US
S
0 B,prot
EQUATION1954 V1 EN-US
The angles φ
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:
158
3U
phase
× + + ×
Z 3 R
1 0 f
is the phase voltage in the fault point before the fault
is the total positive sequence impedance to the fault point. Z
is the total zero sequence impedance to the fault point. Z
is the fault resistance.
( )
× +
3I Z 3R
0 T ,0 N
× + +
3I (Z 3R Z
0 T ,0 N lineAB,0
×
3I
0 A 0
×
3I
0 B 0
j
= × ×
3U 3I cos
0 A 0 A
j
= × ×
3U 3I cos
0 B 0 B
and φ are the phase angles between the residual current and the residual
A B
)
= Z +Z +Z +Z
1 sc T,1 lineAB,1 lineBC,1
= Z +3R +Z +Z
0 T,0 N lineAB,0 lineBC,0
Application manual
1MRK 505 363-UEN A
(Equation 107)
(Equation 108)
(Equation 109)
(Equation 110)
(Equation 111)
(Equation 112)
(Equation 113)