ABB Relion 670 Series Applications Manual page 88

Section 4
Analog inputs
Where:
1)
2)
3)
4)
5)
4.2.4.7 Example on how to connect a neutral point VT to the IED
Figure 25
connection presents secondary voltage proportional to U
In case of a solid earth fault in high impedance earthed or unearthed systems the primary
value of Uo voltage will be equal to:
82
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 where this voltage input is located. It shall be noted that for this voltage
input the following setting values shall be entered:
138
= × =
VTprim 3 138 kV
3
EQUATION1928 V1 EN-US
115
= × =
VT sec 3 115 V
3
EQUATION1929 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.
138
138
3
=
115
115
3
EQUATION1930 V1 EN-US
shows that in this example the first three input channel of the preprocessing
block is not connected in SMT tool.
shows the connection made in Signal Matrix Tool (SMT), which connect this
voltage input to the fourth input channel of the preprocessing function block 4).
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 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
DFTReference shall be set accordingly.
parameters
gives an example on how to connect a neutral point VT to the IED. This type of VT
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1MRK 511 401-UEN Rev. K
(Equation 8)
(Equation 9)
(Equation 10)
GUID-E0EE34BE-A9B0-4F4F-9C06-BBBE87AD0017 v1
to the IED.
0
Bay control REC670
Application manual