Example On How To Connect A Phase-To-Phase Connected Vt To The Ied - ABB REC670 Applications Manual

Section 4
Analog inputs
4.2.4.4
82
Where:
1) shows how to connect three secondary phase-to-ground voltages to three VT inputs on the
IED
2) is the TRM where these three voltage inputs are located. For these three voltage inputs, the
following setting values shall be entered:
VTprim = 132 kV
VTsec = 110 V
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 VT.
66
66
=
110
110
EQUATION1903 V1 EN-US
3) are three connections made in Signal Matrix Tool (SMT), which connect these three voltage
inputs to first three input channels of the preprocessing function block 5). Depending on the
type of functions which need this voltage information, more then one preprocessing block
might be connected in parallel to these three VT inputs.
4) shows that in this example the fourth (that is, residual) input channel of the preprocessing
block is not connected in SMT tool. Thus the preprocessing block will automatically calculate
3Vo inside by vectorial sum from the three phase to ground voltages connected to the first
three input channels of the same preprocessing block. Alternatively, the fourth input channel
can be connected to open delta VT input, as shown in Figure 23.
5) is a Preprocessing block that has the task to digitally filter the connected analog inputs and
calculate:
• fundamental frequency phasors for all input channels
• harmonic content for all 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.
However the following settings shall be set as shown here:
VBase=66 kV (that is, rated Ph-Ph voltage)
If frequency tracking and compensation is required (this feature is typically required only for
IEDs installed in the generating stations) then the setting parameters
set accordingly.

Example on how to connect a phase-to-phase connected VT to the IED

Figure 22 gives an example how to connect a phase-to-phase connected VT to the IED.
It gives an overview of the required actions by the user in order to make this
measurement available to the built-in protection and control functions within the IED.
It shall be noted that this VT connection is only used on lower voltage levels (that is,
rated primary voltage below 40 kV).
3
3
1MRK 511 401-UUS A
(Equation 2)
DFTReference shall be
SEMOD55055-134 v7
Bay control REC670 2.2 ANSI
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