Example On How To Connect An Open Delta Vt To The Ied For High Impedance Earthed Or Unearthed Netwoeks - ABB Relion REC670 Applications Manual

1MRK 511 358-UEN A
4.2.4.5 Example on how to connect an open delta VT to the IED for high
impedance earthed or unearthed netwoeks
Figure 22
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 U
EQUATION1921 V3 EN-US
The primary rated voltage of an open Delta VT is always equal to U
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 22
available to the built-in protection and control functions within the IED as well.
6.6
6.6 kV
3
110 V
3
6.6 kV
3
110 V
3
IEC06000601 V4 EN-US
Figure 22: Open delta connected VT in high impedance earthed power system
Application manual
gives an example about the wiring of an open delta VT to the IED for high impedance
× = ×
3 U 3 U
- -
Ph Ph Ph N
gives overview of required actions by the user in order to make this measurement
L1
L2
L3
kV
3
110 V
3
IED
2
1
+3Uo
. Three series connected
Ph-E
3
SMAI2
BLOCK
REVROT
^GRP2L1
# Not Used
^GRP2L2
# Not Used
^GRP2L3
# Not Used
^GRP2N
4
IEC06000601-4-en.vsdx
Section 4
Analog inputs
SEMOD55055-163 v8
(Equation 3)
5
AI3P
AI1
AI2
AI3
AI4
AIN
71