ABB Relion 670 Series Applications Manual page 75

1MRK 511 401-UEN Rev. K
CTprim =600A
•
• CTsec =5A
CTStarPoint =FromObject
•
The ratio of the first two parameters is only used inside the IED. The third parameter as set in
this example will negate the measured currents in order to ensure that the currents are
measured towards the protected object within the IED.
A third alternative is to have the residual/neutral current from the three-phase CT set
connected to the IED as shown in Figure 14.
L1
CT 800/1
Star Connected
Protected Object
IEC06000644 V4 EN-US
Figure 15: Star 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)
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Bay control REC670
Application manual
L2 L3
IN
IL3
IL2
IL1
Shows how to connect three individual phase currents from a star 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 input 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
•
The ratio of the first two parameters is only used inside the IED. The third parameter as set in this
example will have no influence on measured currents (that is, currents are already measured
towards the protected object).
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IED
3
1
4
2
Section 4
Analog inputs
6
SMAI2
BLOCK AI3P
REVROT AI1
^GRP2L1 AI2
^GRP2L2 AI3
^GRP2L3 AI4
^GRP2N AIN
5
IEC06000644-4-en.vsdx
69