Example How To Connect The Open Delta Vt To The Ied For Low Impedance Earthed Or Solidly Earthed Power Systems - ABB Relion 650 Series Applications Manual

Section 4
Analog inputs
Where:
1)
2)
3)
4)
4.2.1.15 Example how to connect the open delta VT to the IED for low impedance
earthed or solidly earthed power systems
Figure 36
earthed or solidly earthed 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:
U
=
3 Uo
EQUATION1926 V1 EN-US
68
shows how to connect the secondary side of open delta VT to one VT input in the IED.
+3Uo shall be connected to the IED
is TRM or AIM where this voltage input is located. It shall be noted that for this voltage input the
following setting values shall be entered:
= × =
VTprim 3 6.6 11.43
EQUATION1923 V1 EN-US
110
= × =
VT sec 3 110 V
3
EQUATION1924 V1 EN-US
Inside the IED, only the ratio of these two parameters is used. It shall be noted that the ratio of the
entered values exactly corresponds to ratio of one individual open delta VT.
6.6
×
3 6.6
3
=
110
110
3
EQUATION1925 V1 EN-US
shows the connection, which connect this voltage input to the input channel of the preprocessing
function block 5).
Preprocessing block has a task to digitally filter the connected analog inputs and calculate:
• fundamental frequency phasors for all four input channels
• harmonic content for all four input channels
• positive, negative and zero sequence quantities by using the fundamental frequency phasors
for the first three input channels (channel one taken as reference for sequence quantities)
These calculated values are then available for all built-in protection and control functions within the
IED, which are connected to this preprocessing function block. For this application most of the
preprocessing settings can be left to the default values.
If frequency tracking and compensation is required (this feature is typically required only for IEDs
installed in the generating stations) then the setting parameters
accordingly.
gives an example how to connect the open delta VT to the IED for low impedance
- =
Ph Ph U
-
Ph E
3
© Copyright 2011 ABB Power Grids. All rights reserved
kV
1MRK 504 124-UEN B
(Equation 28)
(Equation 29)
(Equation 30)
DFTReference shall be set
SEMOD55055-199 v4
(Equation 31)
Transformer protection RET650
Application manual