Siemens 7SC80 Manual page 262

Functions
2.13 Ground Fault Protection 64, 67N(s), 50N(s), 51N(s)
Displacement Voltage Element V
The displacement voltage 64-1 VGND (address 3108 or 3109) or 64-1 VGND (address 3110) is used to pick
up ground fault detection. At the same time, pickup of the voltage element is a condition for initiation of
direction determination (when setting the direction characteristic to cos φ / sin φ). If the direction char-
acteristic is set toV0/I0 φ mea., the displacement voltage element is not relying on the current elements at
all. Depending on the configuration at address 213 VT Connect. 3ph, only the applicable limit value at
address 3108 or 3109 64-1 VGND or 3110 64-1 VGND is accessible.
If two phase-to-phase voltages and the displacement voltage V
displacement voltage is used directly for ground fault recognition. The threshold for V
(7SJ64) or 3109 (7SJ62) 64-1 VGND, where a more sensitive setting can be made than with a calculated
displacement voltage.
The upper setting threshold for 7SJ64 is higher than for 7SJ62 (see Technical Data).
Please note that when the V
2.1.3.2 Setting
3109 64-1 VGND in primary values, the following conversion formula applies:
[formel-uenprim-uensek-120503-kn, 1, en_US]
If three phase-to-ground voltages are connected to the device, the displacement voltage 3 · V
from the momentary values of phase-to-ground voltages, and address 3110 is where the threshold is to be
set. For the display of parameter 3110 in primary values, the following applies:
[formel-3u0prim-3u0sek-120503-kn, 1, en_US]
If the secondary values of (for example) parameters 3109 and 3110 are set equally, then their primary values
differ by adjustment value Vph/Vdelta.
Example:
Parameter 202
Parameter 203
Parameter 206
Parameter 213
Parameter 3108
The following applies when switching to primary values:
[beispiel-uen-83kv-130503-kn, 1, en_US]
With the following configuration
Parameter 213
Parameter 3110
the following applies when switching to primary values:
[beispiel-3u0-48kv-130503-kn, 1, en_US]
262
o
voltage is connected, the factor (normally = 1.73; see also Section
0
Notes) specified with parameter 206 Vph/Vdelta is used. For display of parameter 3108 or
Vnom PRIMARY
Vnom SECONDARY
Vph/Vdelta
VT Connect. 3ph
64-1 VGND
VT Connect. 3ph
64-1 VGND
are supplied to the device, the measured
0
= 12 kV
= 100 V
= 1.73
= Vab, Vbc,
VGnd
= 40 V
= Van, Vbn, Vcn
= 40 V
E50417-G1140-C486-A8, Edition 07.2017
is set at address 3108
0
is calculated
0
SIPROTEC Compact, 7SC80, Manual