Siemens 7SJ85 - Page 553

Logic for Direction Determination and Pulse Counting
[LoIntdir1, 2, en_US]
Figure 6-116 Logic Diagram of Direction Determination and Pulse Counting
(1) The input signal 3 is from Figure 6-117.
Measurement Values for Direction Determination
The function Directional intermittent ground-fault protection uses the zero-sequence active energy to
determine the direction of the ground-current pulse.
The zero-sequence active energy is calculated from v0(t) and 3i0(t). The zero-sequence voltage v0(t) can
either be measured via the voltage input VN or can be calculated from the sum of 3 phase-to-ground voltages.
The measured value depends on the parameter Connection type of the measuring point V-3ph.
The intermittent ground-fault current 3i0(t) can either be measured via the ground-current input IN or via the
sensitive ground-current input I
NS
. It can also be calculated from the sum of the 3 phase currents. The current
value and its setting range depend on the parameter Connection type of the measuring point I-3ph.
Table 6-12
Threshold Setting Range with Different Connection Types
Connection Type of
the Measuring Point
I-3ph
Current Threshold 3I0/IN CT Terminal Type Threshold Setting
Range
(Secondary)
20
3-phase
Calculated 3I0
21
4 x Protection 0.030 A to 35.000 A
3 x Protection, 1 x sensitive 0.030 A to 35.000 A
4 x Measurement 0.001 A to 1.600 A
3-phase + IN
3-phase + IN-separate
Measured IN
22
4 x Protection 0.030 A to 35.000 A
4 x Measurement 0.001 A to 1.600 A
Measured IN and calculated
3I0 when IN > 1.6 A
3 x Protection, 1 x sensitive 0.001 A to 35.000 A
20
These values apply for a secondary rated current of 1 A. The values need to be multiplied by 5 when the secondary rated current is 5 A.
21
If the connection type is without IN, such as 3-phase, the current threshold value is a calculated 3I0 value.
22
If the connection type is with IN, such as 3-phase + IN, the current threshold value is a measured IN value.
Protection and Automation Functions
6.14 Directional Intermittent Ground-Fault Protection
SIPROTEC 5, Overcurrent Protection, Manual 553
C53000-G5040-C017-8, Edition 07.2017