Siemens SIPROTEC 7SK80 - Directional Ground Overcurrent Protection 67 N

Technical Data
4.4 Directional Ground Overcurrent Protection 67N
SIPROTEC, 7SK80, Manual
E50417-G1140-C344-A4, Release date 08.2010
358
4.4 Directional Ground Overcurrent Protection 67N
Time Overcurrent Elements
Determination of Direction
For Ground Faults
Times
Tolerances
Influencing variables
The same specifications and characteristics apply as for non-directional time overcurrent protection
(see previous Sections).
Moreover, the following data apply to direction determination:
Polarization with zero sequence quantities 3V
0
, 3I
0
Forward range V
ref,rot
± 86°
Rotation of the reference voltage V
ref,rot
-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
, 3I
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
3I
2
≈ 45 mA negative sequence current with I
Nom
= 1 A
3I
2
≈ 225 mA negative sequence current with I
Nom
= 5 A
Pickup times (without inrush restraint, with restraint + 1period)
67N-1, 67-2, 67N-2
- for 2 x setting value
- for 10 x setting value
approx. 45 ms
approx. 40 ms
Dropout times
67N-1, 67N-2 approx. 40 ms
Phase-angle error for ground faults ±3° electrical
Frequency influence approx. 1° in the range of 0.95 < f/f
N
< 1.05