ABB RER670 - Relationships between Setting Parameter Base Current, CT Rated Primary Current and Minimum Pickup of a Protection IED

Protected Object
L1 L2
IED
INP
INS
INS
2
IEC16000139-1-en.vsdx
4
3
CT 600/1A
a)
b)
(+)
(+)
(-)
(-)
(+)
(-)
1
SMAI2
BLOCK
^GRP2L1
^GRP2L2
^GRP2L1L2
^GRP2N
AI2P
AI1
AI2
AI3
AI4
AIN
5
IEC16000139 V1 EN-US
Figure 15: Connections for single-phase CT input
Where:
1) shows how to connect single-phase CT input in the IED.
2) is TRM where these current inputs are located. It shall be noted that for all these
current inputs the following setting values shall be entered.
For connection (a) shown in Fgure 15:
CTprim = 600 A
CTsec = 1A
CTStarPoint = ToObject
For connection (b) shown in Figure
15:
CTprim = 600 A
CTsec = 1A
CTStarPoint = FromObject
3) shows the connection made in SMT tool, which connect this CT input to the fourth input
channel of the preprocessing function block 4).
4) is a Preprocessing block that has the task to digitally filter the connected analog inputs
and calculate values. The calculated values are then available for all built-in protection
and control functions within the IED, which are connected to this preprocessing
function block.
4.2.3 Relationships between setting parameter Base Current, CT
rated primary current and minimum pickup of a protection
IED
GUID-8EB19363-9178-4F04-A6AC-AF0C2F99C5AB v1
Note that for all line protection applications the parameter Base Current (i.e. IBase
setting in the IED) used by the relevant protection function, shall always be set
equal to the lar
gest rated CT primary current among all CT
s involved in the
protection scheme. The rated CT primary current value is set as parameter CTPrim
under the IED TRM settings.
Section 4 1MRK 506 375-UEN A
Analog inputs
54 Railway application RER670 2.2 IEC
Application manual