ABB Relion 670 Series Applications Manual page 66

Section 4
Analog inputs
ANSI05000461 V1 EN-US
Figure 9:
In this example, one IED includes both transformer and line protections and the line protection
uses the same CT as the transformer protection does. For both current input channels, the CT
direction is set with the transformer as reference object. This means that the direction
for the line protection is towards the transformer. To look towards the line, the direction of the
directional functions of the line protection must be set to
is related to the reference object that is the transformer in this case.
When a function is set to
that some directional functions are not symmetrical regarding the reach in forward and reverse
direction. It is in first hand the reach of the directional criteria that can differ. Normally it is not any
limitation but it is advisable to have it in mind and check if it is acceptable for the application in
question.
If the IED has sufficient number of analog current inputs, an alternative solution is shown in Figure
10. The same currents are fed to two separate groups of inputs and the line and transformer
protection functions are configured to the different inputs. The CT direction for the current
channels to the line protection is set with the line as reference object and the directional functions
of the line protection shall be set to
60
Transformer
Setting of current input:
Set parameter
CT_WyePoint with
Transformer as
reference object.
Correct setting is
"ToObject"
Example how to set CT_WyePoint parameters in the IED
Reverse and shall protect an object in reverse direction, it shall be noted
Forward to protect the line.
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Transformer and
Line protection
Setting of current input:
Set parameter
CT_WyePoint with
Transformer as
reference object.
Correct setting is
"ToObject"
Reverse . The direction Forward / Reverse
1MRK 511 401-UUS F
Line
Forward Reverse
Definition of direction for
directional
line functions
en05000461_ansi.vsd
Forward
Bay control REC670
Application manual