ABB REB670 Series, Руководство по применению

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4.2.4.5 Example on how to connect an open delta VT to the IED for high
impedance earthed or unearthed networks
SEMOD55055-163 v9
Figure 30 gives an example about the wiring of an open delta VT to the IED for high impedance
earthed or unearthed power systems. It shall be noted that this type of VT connection
presents a secondary voltage proportional to 3U0 to the IED.
In case of a solid earth fault close to the VT location the primary value of 3Uo will be equal to:
3 0 3 3
Ph Ph Ph N
U U U
- -
= × = ×
EQUATION1921 V3 EN-US
(Equation 3)
The primary rated voltage of an open Delta VT is always equal to U
Ph-E
. Three series connected
VT secondary windings gives a secondary voltage equal to three times the individual VT
secondary winding rating. Thus the secondary windings of open delta VTs quite often have a
secondary rated voltage equal to one third of the rated phase-to-phase VT secondary voltage
(110/3V in this particular example).
Figure 30 gives overview of required actions by the user in order to make this measurement
available to the built-in protection and control functions within the IED as well.
L1
IED
L2
L3
6.6
3
110
3
kV
V
+3Uo
6.6
3
110
3
kV
V
6.6
3
110
3
kV
V
1
2
4
3
# Not Used
5
IEC06000601-4-en.vsdx
# Not Used
# Not Used
SMAI2
BLOCK
REVROT
^GRP2L1
^GRP2L2
^GRP2L3
^GRP2N AI3P
AI1
AI2
AI3
AI4
AI N
IEC06000601 V4 EN-US
Figure 30: Open delta connected VT in high impedance earthed power system
1MRK 505 370-UEN D Section 4
Analog inputs
Busbar protection REB670 79
Application manual