ABB RELION REX640 Technical Manual page 823

1MRS759142 F
occurs on the wye-connected side of the power transformer, negative sequence
current quantities appear on the delta-connected side of the power transformer.
The most common application for the negative sequence overcurrent protection is
probably rotating machines, where negative sequence current quantities indicate
unbalanced loading conditions (unsymmetrical voltages). Unbalanced loading
normally causes extensive heating of the machine and can result in severe damages
even over a relatively short time period.
Multiple time curves and time multiplier settings are also available for coordinating
with other devices in the system.
4.4.1.7 Signals
NSPTOC Input signals
Table 735: NSPTOC Input signals
Name
I3P
BLOCK
ENA_MULT
NSPTOC Output signals
Table 736: NSPTOC Output signals
Name
OPERATE
START
4.4.1.8 NSPTOC Settings
Table 737: NSPTOC Group settings (Basic)
Parameter Values (Range)
Start value 0.01...5.00
Start value Mult 0.8...10.0
Time multiplier 0.025...15.000
Operate delay time 40...200000
Operating curve
1=ANSI Ext. inv.
type
2=ANSI Very inv.
3=ANSI Norm. inv.
4=ANSI Mod. inv.
5=ANSI Def. Time
6=L.T.E. inv.
REX640
Technical Manual
Type
SIGNAL
BOOLEAN
BOOLEAN
Type
BOOLEAN
BOOLEAN
Unit Step
xIn 0.01
0.1
0.005
ms 10
Protection functions
Default Description
- Three-phase currents
0=False Block signal for acti-
vating the blocking
mode
0=False Enable signal for cur-
rent multiplier
Description
Operate
Start
Default
0.30
1.0
1.000
40
15=IEC Def. Time
Description
Start value
Multiplier for scal-
ing the start value
Time multiplier
in IEC/ANSI IDMT
curves
Operate delay time
Selection of time
delay curve type
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