ABB RET670 Applications Manual page 49

1MRK504116-UUS C
A B
CT 800/1
Star Connected
Protected Object
ANSI11000026 V4 EN
Figure 9: Wye connected three-phase CT set with its star point away from the protected object
Application manual
C
IC
IB
IA
In the example in figure 9
described example (figure
CTStarPoint of the used current inputs on the TRM (item 2 in the figure):
• CTprim=600A
• CTsec=5A
• CTWyePoint=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.
IED
2
3
1
case everything is done in a similar way as in the above
8). The only difference is the setting of the parameter
Section 3
IED application
4
SMAI_20_2
BLOCK AI3P
REVROT AI1
5
^GRP2L1 AI2
^GRP2L2 AI3
^GRP2L3 AI4
^GRP2N AIN
ANSI11000026-4-en.vsd
43