ABB RET615 Product Manual page 43

ABB
Transformer Protection and Control
RET615
Product version: 4.0
Table 44. Numerical stabilized low impedance restricted earth-fault protection (LREFPNDF)
Characteristic
Operation accuracy
1)2)
Start time
Reset time
Reset ratio
Retardation time
Operate time accuracy in definite time mode
Suppression of harmonics
1) Current before fault = 0.0, f = 50 Hz, results based on statistical distribution of 1000 measurements
n
2) Includes the delay of the signal output contact
Table 45. Stabilized restricted earth-fault protection (LREFPNDF) main settings
Parameter
Operate value
Restraint mode
Start value 2.H
Minimum operate time
Operation
Operate
I = 2.0 x set
Fault
value
Function
LREFPNDF
LREFPNDF
LREFPNDF
LREFPNDF
LREFPNDF
Value
Depending on the frequency of the current measured: f
±2 Hz
±2.5% of the set value or ±0.002 x I
Minimum Typical
38 ms 40 ms
< 40 ms
Typical 0.96
< 35 ms
±1.0% of the set value or ±20 ms
DFT: -50 dB at f = n x f , where n = 2, 3, 4, 5, ...
n
Value (Range)
5...50 %
None
2nd harmonic
10...50 %
40...300000 ms
Off
On
1MRS756891 F
n
n
Maximum
43 ms
Step
1
-
1
1
-
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