ABB REX 521 Technical Reference Manual, Standard Configurations

1MRS751802-MUM
REX 521
89
Protection Relay
Technical Reference Manual, Standard Configurations
7.1.2. Io>, Io>> and Io>>>
The non-directional earth fault protection function blocks are designed for non-
directional earth fault protection whenever the DT characteristic or, as concerns I
0
>,
the IDMT (Inverse Definite Minimum Time) characteristic is appropriate.
Suppression of harmonics is possible.
Fig. 7.1.2.-1 Function block symbols of Io>, Io>> and Io>>>
Non-directional earth fault protection, low-set stage, Io>
Start current
Operate time in DT mode
Time multiplier in IDMT mode
IEEE time dial in IDMT mode
Operation mode
Measuring mode
Drop-off time of the operate time counter
1.0…500.0% of In
0.05…300.00 s
0.05…1.00
0.5...15.0
Not in use
Definite time
Extremely inverse
Very inverse
Normal inverse
Long time inverse
RI-type inverse
RD-type inverse
IEEE Ext. inv.
IEEE Very inv.
IEEE Inverse
IEEE S.T. inv.
IEEE S.T.E. inv
IEEE L.T.E. inv
IEEE L.T.V. inv
IEEE L.T. inv.
Peak-to-peak
Fundamental frequency
0...1000 ms
Note! The values below apply when f/fn = 0.95...1.05
Operation accuracy
Start time
Reset time
Reset ratio, typically
Retardation time
Operate time accuracy in DT mode
Accuracy class index E in IDMT mode
±2.5% of set value + 0.0005 x In
Injected currents > 2.0 x start current:
internal time < 32 ms
total time < 40 ms
40...1000 ms (depends on the minimum pulse width set
for the trip output)
0.95
< 45 ms
±2% of set value or ±20 ms
Class index E = 5.0 or ±20 ms
Io>
CBFP
B
S1
B
S2
G
ROUP
R
ESET
START
TRIP
CBFP
Io>>
CBFP
BS1
BS2
GROUP
RESET
START
TRIP
CBFP
Io>>>
CBFP
BS1
BS2
GROUP
RESET
START
TRIP
CBFP

ABB REX 521 Specifications

General

Brand	ABB
Model	REX 521
Category	Other
Language	English