ABB Relion REC670 Applications Manual page 67

1MRK 511 358-UEN A
In the example in
example
used current inputs on the TRM (item 2 in the figure):
CTprim =600A
•
CTsec =5A
•
CTStarPoint =FromObject
•
Inside the IED only the ratio of the first two parameters is used. 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 the figure below.
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)
Table continues on next page
Application manual
figure 14 case everything is done in a similar way as in the above described
(figure 13). The only difference is the setting of the parameter
L2 L3
IN
IL3
IL2
IL1
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.
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.
IED
3
1
4
2
Section 4
Analog inputs
CTStarPoint of the
6
SMAI2
BLOCK AI3P
REVROT AI1
^GRP2L1 AI2
^GRP2L2 AI3
^GRP2L3 AI4
^GRP2N AIN
5
IEC06000644-4-en.vsdx
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