Example How To Connect The Open Delta Vt To The Ied For High Impedance Earthed Or Unearthed - ABB Relion 650 Series Applications Manual

1MRK 504 124-UEN B
4.2.1.14 Example how to connect the open delta VT to the IED for high impedance
earthed or unearthed
Figure 35
earthed or unearthed power systems. It shall be noted that this type of VT connection
presents secondary voltage proportional to 3Uo 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 Uo
EQUATION1921 V1 EN-US
The primary rated voltage of such VT is always equal to U
connected VT secondary windings will give the secondary voltage equal to three times the
individual VT secondary winding rating. Thus the secondary windings of such open delta VTs
quite often has a secondary rated voltage equal to one third of the rated phase-to-phase VT
secondary voltage (that is, 110/3V in this particular example). Figure
of required actions by the user in order to make this measurement available to the built-in
protection and control functions within the IED.
6.6
6.6 kV
3
110 V
3
6.6 kV
3
110 V
3
IEC11000033 V1 EN-US
Figure 35: Open delta connected VT in high impedance earthed power system
Transformer protection RET650
Application manual
gives an example how to connect the open delta VT to the IED for high impedance
× = ×
3 U 3 U
- -
Ph Ph Ph E
For correct connections, see the connection diagrams valid for the delivered
IED.
L1
L2
L3
kV
3
110 V
3
© Copyright 2011 ABB Power Grids. All rights reserved
IED
2
1
+3Uo
. Therefore, three series
Ph-E
35 as well gives overview
SMAI_20
3
Section 4
Analog inputs
SEMOD55055-163 v4
(Equation 27)
4
IEC11000033-1-en.vsd
67