62 Electrical design and installation
Manual Power Quality Filter PQFS
Note: Contacts drawn in non-alarm position
24 Vdc
external
supply
NO Alarm
contact of
master 1
NO Alarm
contact of
master 2
External
digital
input
+
-
Figure 45: Cabling of the alarm status of a multi-unit filter consisting of masters only, using the
NO alarm contact on each filter.
In the
above, the external input will be low if:
−
Both master units are in alarm OR
−
The external 24 V power supply fails OR
−
Both filter units are disconnected from the supply.
6.12.2.2
Digital outputs
A second method to implement the alarm functionality is to use the PQF-Manager’s
programmable digital output contacts. Use this approach when the condition for alarm
is uniquely defined, e.g. an alarm has to be given only when the filter trips due to an
unacceptably high network voltage or when the filter trips due to a well-defined internal
error. This type of alarm has to be cabled on the 8 pin terminal block situated at the top
right corner when looking at the PQF-Manager from the rear (Cf.
).
The digital output contacts have a common point (cabled on contacts 1 and 2) and are
of the NO-type (normally open). The contact ratings are:
−
Maximum continuous ac rating: 440 Vac/1.5 A.
−
Maximum continuous dc rating: 110 Vdc/0.3A.
−
The common is rated at 9 A/terminal, giving a total of 18 A.
−
When using a power supply of 24Vdc, a minimum current of 10 mA should be
drawn by the circuit connected to the digital output contact.
shows the status of a digital output contact configured as alarm contact for
different operation modes of the filter.
Table 25: Status of a digital output contact configured as alarm 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 error present
Open
