Single-Ended Fault Locator - GE L90 Instruction Manual

FAULT LOCATOR
Value Relay 1
LOC-REM2 0.0011344 pu
REM1-REM2 0.66289 pu
Applying the results of this table to the equations in the previous section, the algorithm arrives at the following:
• Relay 1 determines remote 1 to tap
• Relay 2 determines local to tap
• Relay 3 determines remote 2 to tap
As a result, the relays use the following data for further calculations.
Table 10-47: Input data for main fault location
Value
Fault segment
L
Z
V
TAP
V
1
I
TAP
I
FLT
The data presented are effectively identical. The difference in current magnitudes results from different per-unit bases at
the three relays (1200 A, 1000 A, and 1600 A). The difference in impedances results from different CT and VT ratios at the
three relays.
The tap voltage is the actual voltage at the tap (0.26558 × 500 kV /
(0.30072 pu = 86.81 kV).
The tap current is the total feed from the tap towards the fault and is 2.9991 × 1200 A = 3.599 pu × 1000 A = 2.2494 pu ×
1600 A = 3.599 kA. The fault current is 7.4992 pu × 1200 A = 8.999 pu × 1000 A = 5.6244 pu × 1600 A = 8.999 kA.
The data results in the following fault locations:
• Relay 1 fault location = 0.4173 pu or 0.4173 × 120 km = 50.0704 km from its remote terminal 1 (relay 2)
• Relay 2 fault location = 0.4172 pu or 0.4172 × 120 km = 50.07 km from local terminal (relay 2)
• Relay 3 fault location = 0.4173 pu or 0.4173 × 120 km = 50.0704 km from its remote terminal 2 (relay 2)
The actual fault location in this example was 50.00 km from relay 2, as shown in the figure.

10.6.3 Single-ended fault locator

When the multi-ended fault locator cannot be executed due to communication channel problems or invalid signals from
remote terminals, then the single-ended method is used to report fault location.
10
10-58
Relay 2
0.66286 pu
0.001137 pu
Relay 1 Relay 2
2 1
120 km 120 km
0.1517 pu ∠80.5° 0.1264 pu ∠80.5°
0.26558 pu ∠2.3467° 0.26559 pu ∠2.3468°
0.30072 pu ∠–12.468° 0.30072 pu ∠–12.468°
2.9991 pu ∠–69.256° 3.599 pu ∠–69.256°
7.4992 pu ∠–78.915° 8.999 pu ∠–78.915°
Figure 10-18: Actual fault location
Relay 3
0.66289 pu
0.66337 pu
Relay 3
3
120 km
0.2023 pu ∠80.5°
0.26558 pu ∠2.3467°
0.30072 pu ∠–12.468°
2.2494 pu ∠–69.256°
5.6244 pu ∠–78.915°
= 76.67 kV). The V
L90 LINE CURRENT DIFFERENTIAL SYSTEM – INSTRUCTION MANUAL
CHAPTER 10: THEORY OF OPERATION
voltage is the voltage at relay 2
1