The actually defined CDC for directional protection activation information (ACD) contains no information about loops.
For voltage measuring functions (especially distance protection) it is helpful to report the (directional) loop activation information as well. This is not possible using CDC ACD.
Activation of L1L2 and L2L3 but not of L3L1 can not be reported by means of the CDC ACD. In this case the data phsA, phsB and phsC would be TRUE. It would not be possible to distinguish this situation from activation of L1L2 and L2L3 and L3L1.
One way to report loops could be the modeling of 6 messages with the CDC SPS. This number increases if the directional information is desired also.
It looks reasonable to combine directional loop information belonging together in one CDC in the same way like the directional protection activation information (CDC ACD).
For a proposal of CDC see the attachment.
29 May 07
In Force (green)
The directional decision is based on the angle between the current in an individual phase and a polarizing quantity. The existing CDC allows the identification of the current direction on a per phase basis for any type of phase or phase to ground fault.
--> not change required
19 Apr 07
In principle I can support this proposal, assuming other protection experts can confimr such a requirement. It woujld then as well have an impact on 7-4, since new data objects for the protection LNs need to be defined.