IG-150-EN version 04; 03/10/16
77
General instructions
ekor.rps
Protection functions. Description and settings
4.8. Current unbalance protection
4.8.1. General description
It contains the timed and instantaneous unbalance
protection functions.
The protection works exactly in the same way as the phase
overcurrent protection, taking as measurement input 3
times the modulus of negative sequence current.
3•
I
2
=
Ia + a
2
•
Ib
+
a
•
Ic
Where a = 1|120°
It must be taken into account that the phase
sequence A-B-C or C-B-A is programmable, so that
the I
2
depends on that setting.
4.8.2. Setting ranges of the timed characteristic (6 tables)
Setting
Min
Max
Step
Notes
Enable
YES/NO/pickup/YES+drop
Pickup.[A]
0.02
40.00
0.01
With standard ratings
0.1
200.0
0.01
With specified ratings
Curve type
Definite time
Normal inverse curve, very inverse curve,
extremely inv. curve
User curve
Time index
0.05
0.5
1.09
30.0
0.01
0.1
For IEC curves
For ANSI curves
Definite time [s]
0
600.0
0.01
These settings can be found in the console on the screen “Overcurrent protection (1)”. TIME SETTING UNBALANCE box
Table 4.13.
Setting ranges of the timed characteristic
The remarks about curves are the same as the ones quoted
for phases.
4.8.3. Setting ranges of the instantaneous characteristic (6 tables)
Setting
Min
Max
Step
Notes
Enable
YES/NO/pickup/YES+drop
Unbalance instantaneous trip [A]
0.02
40.00
0.01
With standard ratings
0.1
200.0
0.01
With specified ratings
Additional time [s]
0
60.00
0.01
These settings can be found in the console on the screen “Overcurrent protection (1)”. TIME SETTING UNBALANCE box
Table 4.14.
Setting ranges of the instantaneous characteristic
The remarks about curves are the same as the ones quoted
for phases
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