GE L90 Instruction Manual page 502

9.4 FAULT LOCATOR
Figure 9–12: RELAY CONNECTIONS FOR MULTI-ENDED FAULT LOCATOR EXAMPLE
The following settings are entered into the relays. These values are calculated in secondary ohms as shown in the following
tables.
Table 9–4: LINE IMPEDANCE SETTINGS (ALL ANGLES ARE 80.5°)
VALUE RELAY 1
Local to tap 1.0219 sec. ohms (relay 1 to tap
in relay 1 secondary ohms)
Remote 1 to tap 1.7520 sec. ohms (relay 2 to tap
in relay 1 secondary ohms)
Remote 2 to tap 0.8030 sec. ohms (relay 3 to tap
in relay 1 secondary ohms)
Assume the following signals are measured by the relays when the fault locator was triggered.
Table 9–5: RELAY MEASUREMENTS (PHYSICAL INPUTS)
VALUE RELAY 1
10.64 A ∠–87.5°
F1
1.652 A ∠88.9°
F2
1.66 A ∠–31.2°
F3
52.71 V ∠0.8°
F5
58.21 V ∠–121.4°
F6
58.93 V ∠121.9°
F7
These measurement are shown below in per-unit values of the CT and VT nominal of the 87L source.
Table 9–6: RELAY MEASUREMENTS (PER-UNIT VALUES)
VALUE RELAY 1
2.128 pu ∠–87.5°
IA
0.3304 pu ∠88.9°
IB
0.332 pu ∠–31.2°
IC
0.91304 pu ∠0.8°
VA (VAB)
1.0083 pu ∠–121.4°
VB (VBC)
1.0208 pu ∠121.9°
VC (VCA)
When subjected to the expanded Clarke transform in the previous sub-section, the local currents yield the following values
9
(in relay per-unit values):
• Relay 1: 1.3839 pu
• Relay 2: 5.4844 pu
• Relay 3: 1.2775 pu
When subjected to the expanded Clarke transform in the previous sub-section, the local voltages yield the following values
(in per-unit values of the nominal primary phase-to-ground voltage):
9-28
channel 1
Relay 1
70 km
channel 2
channel 1
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 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°
1.0359 pu ∠–98.052°
0.94557 pu ∠137.27°
∠–
84.504°
∠–
85.236°
∠–
56.917°
L90 Line Current Differential System
channel 1
120 km
Relay 3
channel 2
831811A1.CDR
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°
0.85917 pu ∠10.1°
0.98909 pu ∠–115.6°
1.0241 pu ∠130.8°
9 THEORY OF OPERATION
Relay 2
channel 2
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)
GE Multilin