Example On How To Connect A Neutral Point Vt To The Ied - ABB REG670 Applications Manual

Section 4
Analog inputs
4.2.4.7
90
Where:
1) shows how to connect the secondary side of open delta VT to one VT input in the IED.
2) 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
EQUATION1928 V1 EN
115
= ×
VT sec 3
EQUATION1929 V1 EN
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
3) shows that in this example the first three input channel of the preprocessing block is not
connected in SMT tool.
4) 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).
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 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
shall be set accordingly.

Example on how to connect a neutral point VT to the IED

Figure 30 gives an example on how to connect a neutral point VT to the IED. This type
of VT connection presents secondary voltage proportional to U
Generator protection REG670 2.2 IEC and Injection equipment REX060, REX061, REX062
+3Uo shall be connected to the IED.
=
138 kV
3
=
115 V
3
1MRK 502 071-UEN -
(Equation 8)
(Equation 9)
(Equation 10)
DFTReference
to the IED.
0
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