GE L90 Instruction Manual page 798

FAULT LOCATOR
The following settings are entered into the relays by you. These values are calculated in secondary ohms as shown in the
following tables.
Table 10-40: Line impedance settings (all angles are 80.5°)
Value
Local to tap
Remote 1 to tap
Remote 2 to tap
Assume that the following signals are measured by the relays when the fault locator is triggered.
Table 10-41: Relay measurements (physical inputs)
Value Relay 1
F1 10.64 A ∠–87.5°
F2 1.652 A ∠88.9°
F3 1.66 A ∠–31.2°
F5 52.71 V ∠0.8°
F6 58.21 V ∠–121.4°
F7 58.93 V ∠121.9°
These measurements are shown as follows in per-unit values of the CT and VT nominal of the 87L source.
Table 10-42: Relay measurements (per-unit values)
Value Relay 1
IA 2.128 pu ∠–87.5°
IB 0.3304 pu ∠88.9°
IC 0.332 pu ∠–31.2°
VA (VAB) 0.91304 pu ∠0.8°
VB (VBC) 1.0083 pu ∠–121.4°
VC (VCA) 1.0208 pu ∠121.9°
When subjected to the expanded Clarke transform in the previous section, the local currents yield the following values (in
relay per-unit values):
• Relay 1: 1.3839 pu ∠–84.504°
• Relay 2: 5.4844 pu ∠–85.236°
Relay 3: 1.2775 pu ∠–56.917°
•
10
When subjected to the expanded Clarke transform in the previous section, the local voltages yield the following values (in
per-unit values of the nominal primary phase-to-ground voltage):
10-56
Figure 10-17: Relay connections for multi-ended fault locator example
Relay 1
1.0219 sec. ohms (relay 1 to tap in
relay 1 secondary ohms)
1.7520 sec. ohms (relay 2 to tap in
relay 1 secondary ohms)
0.8030 sec. ohms (relay 3 to tap in
relay 1 secondary ohms)
Relay 2
8.592 A ∠–88.5°
1.273 A ∠78.6°
1.614 A ∠–43°
76.943 V ∠24.579°
86.321 V ∠–98.052°
78.795 V ∠137.27°
Relay 2
8.592 pu ∠–88.5°
1.273 pu ∠78.6°
1.614 pu ∠–43°
0.92335 pu ∠24.579° 0.85917 pu ∠10.1°
1.0359 pu ∠–98.052° 0.98909 pu ∠–115.6°
0.94557 pu ∠137.27° 1.0241 pu ∠130.8°
Relay 2
6.0833 sec. ohms (relay 2 to tap in
relay 2 secondary ohms)
3.5483 sec. ohms (relay 1 to tap in
relay 2 secondary ohms)
2.7883 sec. ohms (relay 3 to tap in
relay 2 secondary ohms)
Relay 3
9.652 A ∠–43°
5.201 A ∠–99°
6.269 A ∠139.3°
49.6 V ∠10.1°
57.1 V ∠–115.6°
59.12 V ∠130.8°
Relay 3
1.9304 pu ∠–43°
1.0402 pu ∠–99°
1.2538 pu ∠139.3°
L90 LINE CURRENT DIFFERENTIAL SYSTEM – INSTRUCTION MANUAL
CHAPTER 10: THEORY OF OPERATION
Relay 3
1.0707 sec. ohms (relay 3 to tap in
relay 3 secondary ohms)
1.3626 sec. ohms (relay 1 to tap in
relay 3 secondary ohms)
2.3360 sec. ohms (relay 2 to tap in
relay 3 secondary ohms)