ABB Relion 670 Series Applications Manual page 77

1MRK 511 401-UUS F
Protected Object
A
a)
b)
ANSI11000029 V3 EN-US
Figure 18: Connections for single-phase CT input
Where:
1)
2)
3)
4)
4.2.3 Relationships between setting parameter Base Current, CT rated
primary current and minimum pickup of a protection IED
Note that for all line protection applications (e.g. distance protection or line differential
protection) the parameter Base Current (i.e. IBase setting in the IED) used by the relevant
protection function, shall always be set equal to the largest rated CT primary current among all
CTs involved in the protection scheme. The rated CT primary current value is set as parameter
CTPrim under the IED TRM settings.
For all other protection applications (e.g. generator, shunt reactor, shunt capacitor and
transformer protection) it is typically desirable to set
Bay control REC670
Application manual
B C
1
(+)
INS
(-)
(+)
INS
(-)
shows how to connect single-phase CT input in the IED.
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 18:
CTprim = 1000 A
CTsec = 1A
CTWyePoint = ToObject
For connection (b) shown in Figure 18:
CTprim = 1000 A
CTsec = 1A
CTWyePoint = FromObject
shows the connection made in SMT tool, which connect this CT input to the fourth input channel of
the preprocessing function block 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.
If frequency tracking and compensation is required (this feature is typically required only for IEDs
installed in the power plants) then the setting parameters
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IED
2
(+)
(-)
3
IBase parameter equal to the rated current
4
SMAI_20_2
BLOCK AI3P
REVROT AI1
^GRP2_A AI2
^GRP2_B AI3
^GRP2_C AI4
^GRP2_N AIN
ANSI11000029-3-en.vsd
DFTReference shall be set accordingly.
GUID-8EB19363-9178-4F04-A6AC-AF0C2F99C5AB v1
Section 4
Analog inputs
71