4.2.2.3 Example 3One IED used to protect two objects.Transformer andLine protectionTransformerLineSetting of current input:Set parameterCT_WyePoint withTransformer asreference object.Correct setting is"ToObject"ReverseForwardDefinition of direction fordirectionalline functionsSetting of current input:Set parameterCT_WyePoint withTransformer asreference object.Correct setting is"ToObject"en05000461_ansi.vsdANSI05000461 V1 ENFigure 9: Example how to set CT_WyePoint parameters in the IEDIn this example, one IED includes both transformer and line protections and the lineprotection uses the same CT as the transformer protection does. For both current inputchannels, the CT direction is set with the transformer as reference object. This means thatthe direction Forward for the line protection is towards the transformer. To look towardsthe line, the direction of the directional functions of the line protection must be set toReverse. The direction Forward/Reverse is related to the reference object that is thetransformer in this case.When a function is set to Reverse and shall protect an object in reverse direction, it shallbe noted that some directional functions are not symmetrical regarding the reach inforward and reverse direction. It is in first hand the reach of the directional criteria that candiffer. Normally it is not any limitation but it is advisable to have it in mind and check ifit is acceptable for the application in question.If the IED has sufficient number of analog current inputs, an alternative solution is shownin Figure 10. The same currents are fed to two separate groups of inputs and the line andtransformer protection functions are configured to the different inputs. The CT directionSection 4 1MRK 506 369-UUS -Analog inputs70 Line distance protection REL670 2.2 ANSIApplication manual
