9328900990 Rev L BE1-951 Protection and Control 4-17
If the target is enabled for an element, the target reporting function will record a target for all phases that
are above pickup when the protective function trip output is TRUE and the fault recording function trip
logic expression is TRUE. See Section 6, Reporting and Alarm Functions, Fault Reporting, for more
details on the target reporting function. The time overcurrent elements have adaptable targets. If one is
set for directional control, it will report a 67T target (67TA, B, C, N, or G). If one is set for non-directional
control, it will report a 51 target.
BESTlogic Settings for Time Overcurrent
BESTlogic settings are made from the BESTlogic Function Element screen in BESTCOMS.
Figure 4-15
illustrates the BESTCOMS screen used to select BESTlogic settings for the Time Overcurrent function
(the 151N logic is shown). To open the screen, select Overcurrent Protection from the S
creens pull-down
menu and select either the 51 or 151 tab. Then select the BESTlogic button at the bottom of the screen
that corresponds with the element to be modified. Alternately, settings may be made using the SL-51 and
SL-151 ASCII commands.
Figure 4-15. BESTlogic Function Element Screen, Neutral (151N)
At the top center of the BESTlogic Function Element screen is a pull-down menu labeled Logic. This
menu allows viewing of the BESTlogic settings for each preprogrammed logic scheme. A custom logic
scheme must
be created and selected in the Logic pull-down menu at the top of the screen before
BESTlogic settings can be changed. See Section 7, BESTlogic Programmable Logic.
Enable the Time Overcurrent function by selecting its mode of operation from the Mode pull-down menu.
To connect the functions inputs, select the button for the corresponding input in the BESTlogic Function
Element screen. The BESTlogic Expression Builder screen will open. Select the expression type to be
used. Then, select the BESTlogic variable, or series of variables to be connected to the input. Select
Save when finished to return to the BESTlogic Function Element screen. For more details on the
BESTlogic Expression Builder, see Section 7, BESTlogic Programmable Logic. Select Done when the
settings have been completely edited.
The BESTlogic settings for Time Overcurrent are provided in
Table 4-6. These settings enable an
element by attaching it to the CT input circuits and provide blocking control as determined by the logic
expression assigned to the block input.
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