ABB RED650, Applications Manual

Page: 58 / 454

Where:
1) shows how to connect three individual phase currents from a delta connected three-phase
CT set to three CT inputs of the IED.
2) 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
prim
=600A
CT
sec
=5A
• CTStarPoint=ToObject
•
ConnectionType=Ph-Ph
3) 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.
4) 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 DFTReference
shall be set accordingly.
Another alternative is to have the delta connected CT set as shown in figure 14 :
Section 4
1MRK 505 393-UEN B
Analog inputs
52 Line differential protection RED650 2.2 IEC
Application manual