When a binary input is used to set the IED in test mode and a parameter,that requires restart of the application, is changed, the IED will re-entertest mode and all functions will be blocked, also functions that wereunblocked before the change. During the re-entering to test mode, allfunctions will be temporarily unblocked for a short time, which might leadto unwanted operations. This is only valid if the IED is set in TEST modeby a binary input, not by local HMI.The TESTMODE function block might be used to automatically block functions when atest handle is inserted in a test switch. A contact in the test switch (RTXP24 contact 29-30)or an FT switch finger can supply a binary input which in turn is configured to theTESTMODE function block.Each of the functions includes the blocking from the TESTMODE function block.The functions can also be blocked from sending events over IEC 61850 station bus toprevent filling station and SCADA databases with test events, for example during acommissioning or maintenance test.17.5 Change lock function CHNGLCK17.5.1 IdentificationFunction description IEC 61850identificationIEC 60617identificationANSI/IEEE C37.2device numberChange lock function CHNGLCK - -17.5.2 FunctionalityChange lock function CHNGLCK is used to block further changes to the IEDconfiguration and settings once the commissioning is complete. The purpose is to blockinadvertent IED configuration changes beyond a certain point in time.The change lock function activation is normally connected to a binary input.When CHNGLCK has a logical one on its input, then all attempts to modify the IEDconfiguration and setting will be denied and the message "Error: Changes blocked" willbe displayed on the local HMI; in PCM600 the message will be "Operation denied byactive ChangeLock". The CHNGLCK function should be configured so that it iscontrolled by a signal from a binary input card. This guarantees that by setting that signalto a logical zero, CHNGLCK is deactivated. If any logic is included in the signal path tothe CHNGLCK input, that logic must be designed so that it cannot permanently issue aSection 17 1MRK 502 048-UUS ABasic IED functions682Technical manual
