ABB Relion 670 Series Applications Manual page 85

1MRK 511 358-UUS A
A B
Protected Object
ANSI11000027 V2 EN-US
Figure 28: Delta DAB connected three-phase CT set
Where:
1)
2)
3)
4)
Application manual
C
IA-IB
IB-IC
IC-IA
shows how to connect three individual phase currents from a delta connected three-phase CT set to
three CT inputs of the IED.
is the TRM where these current inputs are located. It shall be noted that for all these current inputs the
following setting values shall be entered.
CT
=600A
prim
CT
=5A
sec
• CTWyePoint = ToObject
ConnectionType = Ph-Ph
•
are three connections made in Signal Matrix Tool (SMT), Application configuration tool (ACT), which
connect these three current inputs to first three input channels of the preprocessing function block 4).
Depending on the type of functions which need this current information, more then one preprocessing
block might be connected in parallel to these three CT inputs.
is a Preprocessing block that has the task to digitally filter the connected analog inputs and calculate:
• fundamental frequency phasors for all three input channels
• harmonic content for all three 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.
If frequency tracking and compensation is required (this feature is typically required only for IEDs
installed in the generating stations) then the setting parameters
IED
1
3
Analog inputs
2
4
SMAI_20
ANSI11000027-2-en.vsd
DFTReference shall be set accordingly.
Section 4
79