ABB Relion 670 series, Applications Manual

Page: 73 / 760

4.2.2.5 Example on how to connect a star connected three-phase CT set to the
IED
SEMOD55055-352 v9
Figure 13 gives an example about the wiring of a star connected three-phase CT set to the IED.
It gives also an overview of the actions which are needed to make this measurement available
to the built-in protection and control functions within the IED as well.
For correct terminal designations, see the connection diagrams valid for the
delivered IED.
L1
IL
1
IL
2
IL
3
L2 L3
Protected Object
CT 600/5
Star Connected
IL1
IL2
IL3
IED
IEC13000002-4-en.vsdx
1
2
3
4
SMAI2
BLOCK
REVROT
^GRP2L1
^GRP2L2
^GRP2L3
^GRP2N AI3P
AI1
AI2
AI3
AI4
AI N
5
IN
IEC13000002 V4 EN-US
Figure 13: Star connected three-phase CT set with star point towards the protected object
Where:
1) The drawing shows how to connect three individual phase currents from a star connected three-
phase CT set to the three CT inputs of the IED.
2) The current inputs are located in the TRM. It shall be noted that for all these current inputs the
following setting values shall be entered for the example shown in Figure 13 .
'
• CTprim=600A
• CTsec=5A
• CTStarPoint=ToObject
Inside the IED only the ratio of the first two parameters is used. The third parameter
(CTStarPoint=ToObject) as set in this example causes no change on the measured currents. In other
words, currents are already measured towards the protected object.
Table continues on next page
1MRK 505 343-UEN B Section 4
Analog inputs
67
Application manual