GE L90 Instruction Manual page 526

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
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 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
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 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