GE MiCOM P40 Agile Technical Manual

Also see for MiCOM P40 Agile: Technical manual Technical manual Technical manual Technical manual Technical manual

Contents

Application Notes P44x/EN AP/Hb6MiCOM P40 Agile P442, P444 (AP) 5-1335.6.2 Functional AssignmentEven though settings are made on the relay to control the mode of the intertrip signals, it isnecessary to assign interMiCOM input and output signals in the relay ProgrammableScheme Logic (PSL) if InterMiCOM is to be successfully implemented. Two icons areprovided on the PSL editor of MiCOM S1 Agile for “Integral tripping In” and “Integral trippingout” which can be used to assign the 8 intertripping commands.It should be noted that when an InterMiCOM signal is sent from the local relay, only theremote end relay will react to this command. The local end relay will only react toInterMiCOM commands initiated at the remote end.5.6.3 InterMiCOM SettingsThe settings necessary for the implementation of InterMiCOM are contained within twocolumns of the relay menu structure. The first column entitled “INTERMICOM COMMS”contains all the information to configure the communication channel and also contains thechannel statistics and diagnostic facilities. The second column entitled “INTERMICOMCONF” selects the format of each signal and its fallback operation mode. The followingtables show the relay menus including the available setting ranges and factory defaults.Once the relay operation has been confirmed using the loopback test facilities, it will benecessary to ensure that the communications between the two relays in the scheme arereliable. To facilitate this, a list of channel statistics and diagnostics are available in theInterMiCOM COMMS column:5.6.3.1 Setting GuidelinesThe settings required for the InterMiCOM signalling are largely dependant upon whether adirect or indirect (modem/multiplexed) connection between the scheme ends is used.Direct connections will either be short metallic or dedicated fiber optic (using CILI204) basedand hence can be set to have the highest signalling speed of 19200 b/s. Due to this highsignalling rate, the difference in operating speed between the direct, permissive and blockingtype signals is so small that the most secure signalling (direct intertrip) can be selectedwithout any significant loss of speed. In turn, since the direct intertrip signalling requires thefull checking of the message frame structure and CRC checks, it would seem prudent thatthe “IM# Fallback Mode” be set to “Default” with a minimal intentional delay by setting “IM#FrameSyncTim” to 10 msecs. In other words, whenever two consecutive messages have aninvalid structure, the relay will immediately revert to the default value until a new validmessage is received.For indirect connections, the settings that should be applied will become more applicationand communication media dependent. As for the direct connections, it may be appealing toconsider only the fastest baud rate but this will usually increase the cost of the necessarymodem/multiplexer.In addition, devices operating at these high baud rates may suffer from “data jams” duringperiods of interference and in the event of communication interruptions, may require longerre-synchronization periods.Both of these factors will reduce the effective communication speed thereby leading to arecommended baud rate setting of 9600 b/s. It should be noted that as the baud ratedecreases, the communications become more robust with fewer interruptions, but thatoverall signalling times will increase.Since it is likely that slower baud rates will be selected, the choice of signalling modebecomes significant. However, once the signalling mode has been chosen it is necessary toconsider what should happen during periods of noise when message structure and contentcan be lost.If “Blocking” mode is selected, only a small amount of the total message is actually used toprovide the signal, which means that in a noisy environment there is still a good likelihood ofreceiving a valid message. In this case, it is recommended that the “IM# Fallback Mode” isset to “Default” with a reasonably long “IM# FrameSyncTim”.If “Direct Intertrip” mode is selected, the whole message structure must be valid and checkedto provide the signal, which means that in a very noisy environment the chances of receiving