Relationships Between Setting Parameter Base Current, Ct Rated Primary Current And Minimum Pickup Of A Protection Ied - Hitachi Relion 670 Series Applications Manual

1MRK511407-UUS Rev. N
Protected Object
A
a)
b)
ANSI11000029 V3 EN-US
Figure 17:
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 IBase parameter equal to the rated current of the protected
object. However this is only recommended to do if the rated current of the protected object is within the
Phasor measurement unit RES670
Application manual
B C
1
(+)
INS
(-)
(+)
INS
(-)
Connections for single-phase CT input
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 Figure 17:
CTprim= 1000 A
CTsec= 1A
CTWyePoint=ToObject
For connection (b) shown in Figure 17:
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 DFTReference shall be set accordingly.
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IED
2
(+)
(-)
3
4
SMAI_20_2
BLOCK AI3P
REVROT AI1
^GRP2_A AI2
^GRP2_B AI3
^GRP2_C AI4
^GRP2_N AIN
ANSI11000029-3-en.vsd
GUID-8EB19363-9178-4F04-A6AC-AF0C2F99C5AB v1
Section 4
Analog inputs
55