ABB ret650, Applications Manual

Page: 52 / 392

L1
IL
1
IL
2
IL
3
L2 L3
Protected Object
CT 800/1
Star Connected
IL1
IL2
IL3
IED
IEC11000026-4-en.vsdx
4
1
2
3
SMAI2
BLOCK
REVROT
^GRP2L1
^GRP2L2
^GRP2L3
^GRP2N AI3P
AI1
AI2
AI3
AI4
AI N
5
IN
IEC11000026 V4 EN-US
Figure 12: Star connected three-phase CT set with its star point away from the protected object
In the example, everything is done in a similar way as in the above described
example (Figure
11 ). The only difference is the setting of the parameter
CTStarPoint of the used current inputs on the TRM (item 2 in Figure 12 and 11 ):
• 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
12 .
Section 4
1MRK 504 169-UEN A
Analog inputs
46 Transformer protection RET650 2.2 IEC
Application manual