ABB REG670 - Page 73

Transformer and
Line protection
Transformer
Line
Setting of current input:
Set parameter
CTStarPoint with
Transformer as
reference object.
Correct setting is
"ToObject"
ReverseForward
Definition of direction
for directional
line functions
Setting of current input:
Set parameter
CTStarPoint with
Transformer as
reference object.
Correct setting is
"ToObject"
IED
IEC05000461 V2 EN
Figure 14: Example how to set CTStarPoint parameters in the IED
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
15. 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.
1MRK 502 071-UEN - Section 4
Analog inputs
Generator protection REG670 2.2 IEC and Injection equipment REX060, REX061, REX062 67
Application manual