Numerically Stabilized Low-Impedance Restricted Earth-Fault Protection Lrefpndf (Ansi 87Nli) - ABB RELION REX640 Technical Manual

Protection functions
Name Type
IL1-bias:1 FLOAT32
IL2-bias:1 FLOAT32
IL3-bias:1 FLOAT32
4.3.3.12 Technical data
Table 677: TR3PTDF Technical data
Characteristic
Operation accuracy
Start time
Reset time
Reset ratio
Suppression of harmonics
4.3.4 Numerically stabilized low-impedance restricted earth-
fault protection LREFPNDF (ANSI 87NLI)
4.3.4.1 Identification
Function description
Numerically stabilized low-impe-
dance restricted earth-fault protec-
tion
4.3.4.2 Function block
Figure 421: Function block
1
Current before fault = 0.0 × I
2
Measured with static power output (SPO)
748
Values (Range)
0.00...80.00
0.00...80.00
0.00...80.00
1, 2
Low stage
High stage
, f = 50 Hz. Injected differential current = 2.0 × set operation value.
n n
Unit
Value
Depending on the frequency of the measured current:
f ±2 Hz
n
±3.0% of the set value or ±0.002 × I
Minimum Typical
30 ms 35 ms
17 ms 18 ms
Typically 40 ms
Typically 0.96
DFT: -50 dB at f = n × f , where n = 2, 3, 4, 5, ...
n
IEC 61850 IEC 60617
identification identification
LREFPNDF dIoLo>
1MRS759142 F
Description
Measured bias current
amplitude phase IL1
Measured bias current
amplitude phase IL2
Measured bias current
amplitude phase IL3
n
Maximum
40 ms
20 ms
ANSI/IEEE C37.2
device number
87NLI
REX640
Technical Manual