Example How To Connect Delta Connected Three-Phase Ct Set To The Ied - ABB RELION 670 Series Applications Manual

Section 4
Analog inputs
3)
4)
5)
6)
4.2.2.6

Example how to connect delta connected three-phase CT set to the IED

Figure 18
gives an overview of the required actions by the user in order to make this measurement
available to the built-in protection and control functions in the IED as well.
76
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.
• CTprim=800A
• CTsec=1A
• CTStarPoint=FromObject
• ConnectionType=Ph-N
Inside the IED only the ratio of the first two parameters is used. The third parameter as set in this
example will have no influence on the measured currents (that is, currents are already measured
towards the protected object).
are three connections made in the Signal Matrix tool (SMT), Application configuration tool (ACT),
which connects these three current inputs to the first three input channels on the preprocessing
function block 6). Depending on the type of functions, which need this current information, more
than one preprocessing block might be connected in parallel to these three CT inputs.
is a connection made in the Signal Matrix tool (SMT), Application configuration tool (ACT), which
connects the residual/neutral current input to the fourth input channel of the preprocessing
function block 6). Note that this connection in SMT shall not be done if the residual/neutral current
is not connected to the IED. In that case the pre-processing block will calculate it by vectorial
summation of the three individual phase currents.
is a Preprocessing block that has the 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 how to connect a delta connected three-phase CT set to the IED. It
For correct terminal designations, see the connection diagrams valid for the
delivered IED.
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