Numerical Stabilized Low Impedance Restricted Earth-Fault Protection (Lrefpndf); Numerical Stabilized Low Impedance Restricted Earth-Fault Protection (Lrefpndf) Main Settings; High-Impedance Based Restricted Earth-Fault Protection (Hrefpdif); High-Impedance Based Restricted Earth-Fault Protection (Hrefpdif) Main Settings - ABB RET620 Product Manual

Transformer Protection and Control
RET620
Product version: 2.0
Table 57. 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 58. Numerical stabilized low impedance restricted earth-fault protection (LREFPNDF) main settings
Parameter
Operate value
Restraint mode
Start value 2.H
Minimum operate time
Operation
Table 59. High-impedance based restricted earth-fault protection (HREFPDIF)
Characteristic
Operation accuracy
Start time 1)2)
Reset time
Reset ratio
Retardation time
Operate time accuracy in definite time mode
1) Current before fault = 0.0 × I , f = 50 Hz
n n
2) Includes the delay of the signal output contact
Table 60. High-impedance based restricted earth-fault protection (HREFPDIF) main settings
Parameter
Operate value
Minimum operate time
Operation
38
Operate value
I = 2.0 x set
Fault
Function
LREFPNDF
LREFPNDF
LREFPNDF
LREFPNDF
LREFPNDF
Operate value
I = 2.0 × set
Fault
Operate value
I = 10.0 × set
Fault
Function
HREFPDIF
HREFPDIF
HREFPDIF
Value
Depending on the frequency of the current measured: f
±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
Value
At the frequency f = f
n
±1.5% of the set value or ±0.002 × I
Typical 22 ms (±5 ms)
Typical 15 ms (±5 ms)
< 60 ms
Typical 0.96
< 60 ms
±1.0% of the set value or ±20 ms
Value (Range)
1.0...50.0 %
40...300000 ms
Off
On
1MRS757846 A
±2 Hz
n
n
Maximum
43 ms
Step
1
-
1
1
-
n
Step
0.1
1
-
ABB