ABB REC650 Applications Manual page 59

1MRK 511 286-UUS A
Application manual
Z
0, net
= ×
3 I
0 T
+
Z Z
0, net 0 T ×
2 Z
1, net
GUID-CC2E2412-4939-4285-A491-FCCC0AE0F939-ANSI V1 EN
The residual current from the transformer during a single phase-ground-fault and
with minimum short circuit power is:
Z
0, net
= ×
3 I
0 T
+
Z Z
0, net 0 T ×
2 Z
1, net
GUID-991D27BC-4413-4A9B-BF49-F25986545C73-ANSI V1 EN
The residual current from the transformer during a phase-to-phase to ground-fault
and with maximum short circuit power is:
Z
0, net
= ×
3 I
0 T
+
Z Z
0, net 0 T + ×
Z
1, net
GUID-CA17A1A5-E141-4F0B-B7C0-74683F9F9AD1-ANSI V1 EN
The residual current from the transformer during a phase-to-phase to ground-fault
and with minimum short circuit power is:
Z
0, net
= ×
3 I
0 T
+
Z Z
0, net 0 T + ×
Z
1, net
GUID-933BE756-31CD-45BA-B3EB-5DC00CA25DC0-ANSI V1 EN
To assure that the protection detects all ground-faults on the 145 kV busbar the
protection should be set as follows:
Pickup1 ≤ 0.75 · 2.2 = 1.65 kA = 687 % IBase
85%
ANSI11000128 V1 EN
Figure 11: Fault calculation for 145 kV residual overcurrent protection
selectivity
REC650 setting examples
×
3 V j 15
= ×
×
Z Z
+
j 15 j 42 2 3.5
0, net 0 T
+
+
Z Z
0, net 0 T
×
3 V j 20
= ×
×
Z Z
+
j 20 j 42 2 10
0, net 0 T
+
+
Z Z
0, net 0 T
×
3 V j 15
= ×
×
Z Z
+
j 15 j 42
0, net 0 T
2
+
Z Z
0, net 0 T
×
3 V j 20
= ×
×
Z Z +
j 20 j 42
0, net 0 T
2
+
Z Z
0, net 0 T
51N_67N
145 kV
3
Section 3
×
3 145
=
3.7 kA
×
j 15 j 42
× +
j
+
j 15 j 42
(Equation 14)
×
3 145
=
2.4 kA
×
j 20 j 42
× +
j
+
j 20 j 42
(Equation 15)
×
3 145
=
2.6 kA
×
j 15 j 42
+ ×
j 3.5 2
+
j 15 j 42
(Equation 16)
×
3 145
=
2.2 kA
×
j 20 j 42
+ ×
j 10 2
+
j 20 j 42
(Equation 17)
REC650
1
Ph-Ph
1
Y
3
Y
1
ANSI11000128-1-en.vsd
22 kV
Y
53