6.1.3.13 Trip arrangement with one-phase versionWhen one-phase version of the IED is used it is typically required to have three IEDs (thatis, one per phase). Thus, when busbar protection in one IED operates the trip commandswill be given to all bays but internal circuit breaker failure function will be started in thesame phase only. In order to secure internal breaker failure picking-up in all three phasesit is advisable to do the following. Connect Zone A trip signal from one IED to the externaltrip input of the Zone A in the other two IEDs. Thus all three IEDs will then issue trip inZone A and pick-up internally circuit breaker failure protection in all three phases.Note that:• similar arrangements shall be done for Zone B• this have to be done between all three IEDs (that is, three times)Such a scheme can be arranged in one of the following ways:• by wiring between three IEDs• by using GOOSE messages when IEC 61850-8-1 is used• by using LDCM communication module.Note that in this case the external trip signal from other two IEDs shall be arranged viapulse timer in configuration in order to avoid locking of the trip signal between three IED.Such arrangement via GOOSE is given in figure 52:Section 6 1MRK 505 337-UUS -Differential protection126Application manual
