Example How To Connect The Open Delta Vt To The Ied For Low Impedance Earthed Or Solidly Earthed Power Systems - ABB Relion REC670 Applications Manual

Section 4
Analog inputs
Where:
1)
2)
3)
4)
5)
4.2.4.6 Example how to connect the open delta VT to the IED for low impedance
earthed or solidly earthed power systems
Figure 23
impedance earthed or solidly earthed power systems. It shall be noted that this type of VT
connection presents secondary voltage proportional to 3U
In case of a solid earth fault close to the VT location the primary value of 3Uo will be equal to:
72
shows how to connect the secondary side of the open delta VT to one VT input on the IED.
+3U0 shall be connected to the IED
is the TRM 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 that in this example the first three input channel of the preprocessing block is not
connected in SMT tool or ACT tool.
shows the connection made in Signal Matrix Tool (SMT), Application configuration tool (ACT),
which connect this voltage input to the fourth input channel of the preprocessing function block
5).
is a Preprocessing block that has the task to digitally filter the connected analog input 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 in the configuration tool. 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 about the connection of an open delta VT to the IED for low
kV
1MRK 511 358-UEN A
DFTReference shall be set
to the IED.
0
Application manual
(Equation 4)
(Equation 5)
(Equation 6)
SEMOD55055-199 v6