Sensitive Earth-Fault Protection 50Sef; Identification; Function Block; Functionality - ABB RELION 620 Series Technical Manual

Section 4
Protection functions
4.1.6
4.1.6.1
4.1.6.2
4.1.6.3
232
Characteristic
Reset time
Reset ratio
Retardation time
Trip time accuracy in definite time mode
Trip time accuracy in inverse time mode
Suppression of harmonics
Measurement mode = default (depends on stage), current before fault = 0.0 × I
1)
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 Pickup value = 2.5 × I

Sensitive earth-fault protection 50SEF

Identification

Function description
Non-directional sensitive earth-fault
protection

Function block

GUID-A8245C60-3A48-4723-9C22-C5E177A4AC30 V2 EN
Figure 105: Function block

Functionality

A small percentage of the ground faults have very large impedance. It is possible to detect
these faults by using a very sensitive earth-fault protection. It is applicable for networks
where normal unbalance current level is low enough to allow for sensitive setting of
50SEF.
Value
<40 ms
Typically 0.96
<30 ms
±1.0% of the set value or ±20 ms
±5.0% of the theoretical value or ±20 ms
RMS: No suppression
DFT: -50 dB at f = n × f
Peak-to-Peak: No suppression
, Pickup value multiples in range of 1.5...20
n
IEC 61850 IEC 60617
identification identification
EFLPTOC Io>
1MAC504801-IB E
3)
, where n = 2, 3, 4, 5,...
n
, f = 60 Hz, ground-fault
n n
ANSI/IEEE C37.2
device number
50SEF
620 series ANSI
Technical Manual