Table 35. Directional earth-fault protection (DEFxPDEF)
Characteristic
Value
Operation accuracy
Depending on the frequency of the current measured: f
n
±2 Hz
DEFLPDEF
Current:
±1.5% of the set value or ±0.002 x I
n
Voltage
±1.5% of the set value or ±0.002 x U
n
Phase angle:
±2°
DEFHPDEF
Current:
±1.5% of the set value or ±0.002 x I
n
(at currents in the range of 0.1…10 x I
n
)
±5.0% of the set value
(at currents in the range of 10…40 x I
n
)
Voltage:
±1.5% of the set value or ±0.002 x U
n
Phase angle:
±2°
Start time
1)2)
Minimum
Typical
Maximum
DEFHPDEF
I
Fault
= 2 x set
Start value
42 ms
44 ms
46 ms
DEFLPDEF
I
Fault
= 2 x set
Start value
61 ms
64 ms
66 ms
Reset time
< 40 ms
Reset ratio
Typical 0.96
Retardation time
< 30 ms
Operate time accuracy in definite time mode
±1.0% of the set value or ±20 ms
Operate time accuracy in inverse time mode
±5.0% of the theoretical value or ±20 ms
3)
Suppression of harmonics
RMS: No suppression
DFT: -50 dB at f = n x f
n
, where n = 2, 3, 4, 5,…
Peak-to-Peak: No suppression
1)
Set
Operate delay time = 0.06 s,Operate curve type = IEC definite time, Measurement mode = default (depends on stage), current before fault = 0.0 x I
n
, f
n
= 50 Hz, earth-fault current
with nominal frequency injected from random phase angle, results based on statistical distribution of 1000 measurements
2)
Includes the delay of the signal output contact
3)
Maximum
Start value = 2.5 x I
n
,
Start value multiples in range of 1.5 to 20
Transformer Protection and Control
1MRS757846 A
RET620
Product version: 2.0
30
ABB
