Where:
1) shows how to connect the secondary side of a phase-to-phase VT to the VT inputs on the IED
2) is the TRM or AIM where this voltage input is located. The following setting values shall be entered:
VTprim
=13.8 kV
VTsec
=120 V
3)
are three connections, which connects these three voltage inputs to three input channels of the
preprocessing function block 4). 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
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. 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.
1MRK 511 286-UUS A Section 4
Analog inputs
75
Application manual
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