Name Type Values (Range) Unit Description
3=test
4=test/blocked
5=off
4.2.5.10 Technical data
Table 582: MREFPTOC Technical data
Characteristic Value
Operation accuracy Depending on the frequency of the current measured: f
n
±2 Hz
±1.5% of the set value or ±0.002 × I
n
Start time
1, 2
I
Fault
= 1.2 × set
Start
value
Minimum Typical Maximum
30 ms 34 ms 38 ms
Reset time <50 ms
Reset ratio Typically 0.96
Retardation time <50 ms
Operate time accuracy ±1.0% of the set value of ±20 ms
Suppression of harmonics -50 dB at f = n × f
n
, where n = 2, 3, 4, 5,…
4.2.6 Harmonics-based earth-fault protection HAEFPTOC (ANSI
51NH)
4.2.6.1 Identification
Description IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
Harmonics-based earth-fault pro-
tection
HAEFPTOC Io>HA 51NH
4.2.6.2 Function block
Figure 300: Function block
4.2.6.3 Functionality
The harmonics-based earth-fault protection function HAEFPTOC is used instead
of a traditional earth-fault protection in networks where a fundamental frequency
component of the earth-fault current is low due to compensation.
1
Current before fault = 0.0 × 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.
1MRS759142 F Protection functions
REX640
Technical Manual
521
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