ABB Relion 670 Series Applications Manual page 72

Section 4
Analog inputs
A B
CT 800/1
Wye Connected
Protected Object
ANSI11000026 V5 EN-US
Figure 14: Wye connected three-phase CT set with its wye point away from the protected object
In the example, everything is done in a similar way as in the above described example (Figure 13).
The only difference is the setting of the parameter
TRM (item 2 in Figure
CTprim =600A
•
• CTsec =5A
CTWyePoint =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.
66
C
1
IC
IB
IA
14 and 13):
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IED
2
3
CTStarPoint of the used current inputs on the
1MRK 511 401-UUS F
4
SMAI_20_2
BLOCK AI3P
REVROT AI1
5
^GRP2_A AI2
^GRP2_B AI3
^GRP2_C AI4
^GRP2N AIN
ANSI11000026-5-en-.vsd
Bay control REC670
Application manual