ABB RED650 Applications Manual page 54

Section 4
Analog inputs
L1
CT 800/1
Star Connected
Protected Object
IEC11000026 V4 EN-US
Figure 11: Star connected three-phase CT set with its star point away from the protected object
48
L2 L3
IN
IL3
IL2
IL1
In the example, everything is done in a similar way as in the above described
example (Figure 10). The only difference is the setting of the parameter
CTStarPoint of the used current inputs on the TRM (item 2 in Figure
• 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 11.
IED
2
1
3
Line differential protection RED650 2.2 IEC
1MRK 505 393-UEN B
4
SMAI2
BLOCK AI3P
REVROT AI1
5
^GRP2L1 AI2
^GRP2L2 AI3
^GRP2L3 AI4
^GRP2N AI N
IEC11000026-4-en.vsdx
11 and 10):
Application manual