ABB PQFM, Instruction Manual

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82 Electrical design and installation  Manual Power Quality Filter PQFM
A second use of the digital outputs is to monitor the status of individual master units in
a multi-filter system. This can be done by assigning the function ‘Unit missing’ (‘Unit
miss.) to a digital output. In that case the digital output of the master controlling the
complete system will activate the digital output considered when one of the units in a
filter system is not operational due to error.
In order to obtain full redundancy with filters consisting of more than one master unit,
the digital outputs of all the units in a multi-master arrangement have to set up and
cabled in the same way. The cabling scheme is given in
Figure 63 .
Once the cabling has been finished, the power to the filter may then be restored.
6.12.3 Cabling of warning functionality
A warning condition is a condition that can be set up by the user in such a way that if the
condition is met, a digital output contact of the PQF-Manager user interface (Cf
. Figure
57 ) is closed. As an example consider a case where the user has set up an upper warning
level for the network voltage. If the level measured by the filter becomes higher than the
predefined warning level and this condition remains valid for a preset time, the
associated digital output will be closed. By monitoring the digital output, the customer
will then know when the network voltage becomes too high and subsequently he can
take appropriate action.
Note that the warning functionality is not associated with a filter trip. It only has a
monitoring function.
Table 31 describes the behavior of the digital output contact
configured as warning contact for different filter operating modes.
Table 31: State of a digital output contact configured as warning contact for different filter
operation modes
Filter state Normally open digital contact state
Disconnected from the supply Open
Filter (auxiliaries) connected to the
supply, no warning present
Open
Filter (auxiliaries) connected to the
supply, predefined warning present
Closes when warning present for pre-defined time.
Otherwise, contact remains open.
Filter (auxiliaries) connected to the
supply, predefined warning disappears
When closed before and warning disappears for at
least the predefined time, contact opens.
When closed before and warning disappears for a
time smaller than predefined time, contact
remains closed.
Otherwise, contact remains open.
Table 32 gives a list of the warning conditions that can be assigned to a digital output.