scheider electric MiCOM P746, Technical Manual

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Programmable Logic P746/EN PL//G31
MiCOM P746 (PL) 7-
5
PL
1.4 Warnings
Before the scheme is sent to the relay checks are done. Various warning messages may be
displayed as a result of these checks.
The Editor first reads in the model number of the connected relay, and then compares it with
the stored model number. A "wildcard" comparison is employed. If a model mismatch occurs
then a warning will be generated before sending commences. Both the stored model number
and that read-in from the relay are displayed along with the warning; the onus is on you to
decide if the settings to be sent are compatible with the connected relay. Wrongly ignoring
the warning could lead to undesired behaviour in the relay.
If there are any potential problems of an obvious nature then a list will be generated. The
types of potential problems that the program attempts to detect are:
•
One or more gates, LED signals, contact signals, and/or timers have their outputs linked
directly back to their inputs. An erroneous link of this sort could lock up the relay, or
cause other more subtle problems to arise.
•
Inputs to Trigger (ITT) exceed the number of inputs. A programmable gate has its ITT
value set to greater than the number of actual inputs; the gate can never activate. Note
that there is no lower ITT value check. A 0-value does not generate a warning.
•
Too many gates. There is a theoretical upper limit of 256 gates in a scheme, but the
practical limit is determined by the complexity of the logic. In practice the scheme would
have to be very complex, and this error is unlikely to occur.
•
Too many links. There is no fixed upper limit to the number of links in a scheme.
However, as with the maximum number of gates, the practical limit is determined by the
complexity of the logic. In practice the scheme would have to be very complex, and this
error is unlikely to occur.