ABB Relion 670 Series Applications Manual page 83

1MRK 511 358-UUS A
A B
CT 800/1
Wye Connected
Protected Object
ANSI06000644 V2 EN-US
Figure 27: Wye connected three-phase CT set with its star point away from the protected object and the
residual/neutral current connected to the IED
Where:
1)
2)
3)
4)
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Application manual
C
IN
IC
IB
IA
The drawing shows how to connect three individual phase currents from a wye connected three-phase
CT set to the three CT inputs of the IED.
shows how to connect residual/neutral current from the three-phase CT set to the fourth inputs in the
IED. It shall be noted that if this connection is not made, the IED will still calculate this current internally
by vectorial summation of the three individual phase currents.
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.
IED
3
1
1
2 AI 01 (I)
3
AI 02 (I)
4
5
AI 03 (I)
6
7
AI 04 (I)
8
9
AI 05 (I)
2 10
11
AI 06 (I)
12
6
4
SMAI2
BLOCK
^GRP2_A
^GRP2_B
^GRP2_C
^GRP2N
TYPE
5
ANSI06000644-2-en.vsd
Section 4
Analog inputs
AI3P
AI1
AI2
AI3
AI4
AIN
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