Directional Overcurrent Protection
Time Overcurrent Elements
The same specifications and characteristics apply as for non-directional time overcurrent protection (see
previous Sections).
Determination of Direction
Moreover, the following data apply to direction determination:
For Phase Faults
Polarization With cross-polarized voltages;
with voltage memory 2 s
Forward Range V
ref,rot
± 86°
Rotation of the reference voltage V
ref,rot
–180° to +180°
Increments 1°
Dropout difference 3°
Directional sensitivity Unlimited for single and two phase faults
For three phase faults, dynamically unlimited, steady-
state
approx. 7V phase-to-phase
For Ground Faults
Polarization
with zero sequence quantities 3V
0
, 3Ι
0
Forward Range V
ref,rot
± 86°
Rotation of the reference voltage V
ref,ot
–180° to +180°
Increments 1°
Dropout difference 3°
Directional Sensitivity V
N
≈ 2.5 V displacement voltage, measured
3V
0
≈ 5 V displacement voltage, calculated
Polarization
with negative sequence quantities 3V
2
, 3Ι
2
Forward Range V
ref,rot
± 86°
Rotation of the reference voltage V
ref,rot
–180° to +180°
Increments 1°
Dropout difference 3°
Directional Sensitivity 3V
2
≈ 5 V negative sequence voltage
3Ι
2
≈ 45 mA negative sequence current with Ι
Nom
= 1 A
3Ι
2
≈ 225 mA negative sequence current with Ι
Nom
=
5 A
Times
Pickup times (without inrush restraint, with restraint + 1 period)
50-1, 50-2, 50-3, 50N-1, 50N-2, 50N-3
- for 2 x setting value
- for 10 x setting value
approx. 45 ms
approx. 40 ms
4.4
Technical Data
4.4 Directional Overcurrent Protection
376 SIPROTEC 4, 7SJ80, Manual
E50417-G1140-C343-A8, Edition 12.2017
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