Siemens siprotec SJ62 User Manual page 215

2 Functions
Displacement
Voltage V
0
213
the maximum expected operational phase-to-ground voltage, but less than the
minimum expected operational phase-to-phase voltage. For V
mately 75 V is a typical setting. These settings have no significance in a grounded
system.
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 directional determination. Depending on the
setting at address 213 VT Connect. 3ph, only the applicable threshold address
3108 64-1 VGND, 3109 64-1 VGND or 3110 64-1 VGND is accessible:
That is, if two phase-to-phase voltages and the displacement voltage V
to the device, the measured displacement voltage is used directly for ground fault rec-
ognition. The threshold for V
where a more sensitive setting can be made than with a calculated displacement volt-
age. The upper setting threshold for 7SJ64 is higher than for 7SJ62/63 (see Technical
Data). Please note that with phase-to-phase voltage V
1.73; see also Section 2.1.3.2) specified with parameter 206 Vph / Vdelta is used.
For display of parameter 3108 64-1 VGND or 3109 64-1 VGND in primary values,
the following conversion formula applies:
If three phase-to-ground voltages are connected to the device, the displacement
voltage 3 · V is calculated from the momentary values of phase-to-ground voltages,
0
and address 3110 is where the threshold is to be set. For the display of the parame-
ters 3110 in primary values, the following applies:
If secondary values of (for example) parameter 3109 and 3110 are set the same, their
primary values differ by the adaptation factor Vph / Vdelta.
Example:
Parameter 202 Vnom PRIMARY
Parameter 203 Vnom SECONDARY
Parameter 206 Vph / Vdelta
Parameter 213 VT Connect. 3ph
Parameter 3109 64-1 VGND
is set at address 3108 (7SJ62/63) or 3109 (7SJ64),
0
= 12 kV
= 100 V
= 1.73
= Vab, Vbc, VGnd
= 40 V
= 100 V, approxi-
Nom
are supplied
0
, the factor (in normal case =
0
SIPROTEC 4, 7SJ62/63/64 Handbuch
C53000-G1140-C147-A, Edition 07.2015