Example On How To Connect An Open Delta Vt To The Ied For High Impedance Grounded Or Ungrounded Networks - Hitachi Relion 670 Series Applications Manual

1MRK511407-UUS Rev. N
3)
4)
5)
4.2.4.5 Example on how to connect an open delta VT to the IED for high impedance
grounded or ungrounded networks
Figure 22
grounded or ungrounded power systems. It shall be noted that this type of VT connection presents a
secondary voltage proportional to 3V0 to the IED.
In case of a solid ground fault close to the VT location the primary value of 3Vo will be equal to:
=
3 Vo 3
EQUATION1922-ANSI V1 EN-US
The primary rated voltage of an open Delta VT is always equal to V
secondary windings gives a secondary voltage equal to three times the individual VT secondary winding
rating. Thus the secondary windings of open delta VTs quite often have a secondary rated voltage equal
to one third of the rated phase-to-phase VT secondary voltage (110/3V in this particular example).
Figure 22
the built-in protection and control functions within the IED as well.
Phasor measurement unit RES670
Application manual
are three connections made in the Signal Matrix tool (SMT), Application configuration tool (ACT), which
connects 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 than one preprocessing block
might be connected in parallel to these three VT inputs
shows that in this example the fourth (that is, residual) input channel of the preprocessing block is not connected
in SMT. Note. If the parameters V
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. However the following settings shall be set as shown
here:
ConnectionType=Ph-Ph
VBase=13.8 kV
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 about the wiring of an open delta VT to the IED for high impedance
× = ×
V 3 V
- -
Ph Ph Ph Gnd
gives overview of required actions by the user in order to make this measurement available to
© 2017 - 2023 Hitachi Energy. All rights reserved
, V , V , V should be used the open delta must be connected here.
A B C N
. Three series connected VT
Ph-Gnd
Section 4
Analog inputs
SEMOD55055-163 v9
(Equation 3)
61