ABB Relion 670 Series Applications Manual page 466

Section 17
Logic
IEC09000310 V2 EN-US
Figure 237: Example designation, serial execution number and cycle time for logic
The execution of different function blocks within the same cycle is determined by the order of
their serial execution numbers. Always remember this when connecting two or more logical
function blocks in series.
17.7 Fixed signal function block FXDSIGN
17.7.1 Application
The Fixed signals function (FXDSIGN) has nine pre-set (fixed) signals that can be used in the
configuration of an IED, either for forcing the unused inputs in other function blocks to a
certain level/value, or for creating certain logic. Boolean, integer, floating point, string types of
signals are available.
One FXDSIGN function block is included in all IEDs.
Example for use of GRP_OFF signal in FXDSIGN
The Restricted earth fault function (REFPDIF) can be used both for auto-transformers and
normal transformers.
When used for auto-transformers, information from both windings parts, together with the
neutral point current, needs to be available to the function. This means that three inputs are
needed.
IEC09000619 V3 EN-US
Figure 238: REFPDIF function inputs for autotransformer application
460
function that also propagates timestamp and quality of input signals
Always be careful when connecting function blocks with a fast cycle time to
function blocks with a slow cycle time.
Remember to design the logic circuits carefully and always check the execution
sequence for different functions. In other cases, additional time delays must be
introduced into the logic schemes to prevent errors, for example, race between
functions.
REFPDIF
I3PW1CT1
I3PW2CT1
I3P
IEC09000619_3_en.vsd
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