Hitachi Relion 670 Series Applications Manual page 50

Section 4
Analog inputs
ANSI05000461 V1 EN-US
Figure 8:
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 Forward 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 Reverse. The direction Forward/Reverse is related to the reference object that
is the transformer in this case.
When a function is set to Reverse and shall protect an object in reverse direction, it shall be noted 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 9. 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
Forward to protect the line.
44
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
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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"
1MRK511407-UUS Rev. N
Line
Forward Reverse
Definition of direction for
directional
line functions
en05000461_ansi.vsd
Phasor measurement unit RES670
Application manual