It is possible to power-cycle the IED in this state without losing the forcingstates and values. This means that once a signal is forced, and the IEDremains in IED test mode, the input or output will appear “frozen” at thevalue selected by the user, even if the IED is switched off and back onagain.Freezing a signal value without changing it• Set the status of a signal to Forced, in the forcing menu that corresponds to the I/Ocard in question. See example of LHMI menu in figure 22IEC15000020 V1 ENFigure 22: Example of LHMI menu using BIM3The signal “freezes” and will not change value even if, for example, a binary input signalvoltage changes level, or if a binary output is activated as the result of a protection functionblock activating.10.8.3.2 Forcing by using PCM600In PCM600 the concept is a bit different compared to LHMI. The forcing is accomplishedby entering a forcing session. Within such a session, multiple signals on multiple I/Oboards may be edited and changed at the same time and has no effect on the IED. Once theuser is satisfied with the forcing setup, then all the changes can be effectuatedsimultaneously towards the IED, potentially changing inputs and outputs on multiple I/Oboards at the same time. It is also possible to abort this operation (described in step 6below) and to undo all forcing.Section 10 1MRK 504 165-UUS -Testing IED operation100 Transformer protection RET670 2.2 ANSICommissioning manual
