Example On How To Connect A Neutral Point Vt To The Ied - Hitachi Relion 670 Series Applications Manual

1MRK511407-UUS Rev. N
Where:
1)
2)
3)
4)
5)
4.2.4.7

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

Figure 24
presents secondary voltage proportional to V
Phasor measurement unit RES670
Application manual
shows how to connect the secondary side of open delta VT to one VT input in the IED.
+3Vo 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 parameters
DFTReference shall be set accordingly.
gives an example on how to connect a neutral point VT to the IED. This type of VT connection
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to the IED.
0
Analog inputs
(Equation 8)
(Equation 9)
(Equation 10)
GUID-E0EE34BE-A9B0-4F4F-9C06-BBBE87AD0017 v1
Section 4
65