Manual Power Quality Filter PQFM
Electrical design and installation 79
shows a cabling scheme using a 24 Vdc supply in conjunction with the NO alarm
contact. The scheme assumes that an external digital input monitors the alarm contact
of the filter. In this case the voltage applied to the digital input will be low when:
−
The filter is disconnected from the supply OR.
−
The filter trips due to an error OR.
−
The external 24 Vdc power supply fails.
The voltage applied to the external digital input is high when:
−
The filter is connected to the supply and is not in error AND
−
The external 24 Vdc power supply is in working order.
15
(a)
16
(a)
17
Alarm
outputs
NO
NC
24 Vdc
external
supply
Remark:
(a)
Right hand terminal block when looking from rear, counting from top to
bottom
External
digital
input
+
-
+
-
PQF-Manager
Figure 62: Alarm cabling example using NO alarm contact and external digital input
When the filter system consists of multiple master-units and an alarm contact is needed
to signal when the complete system is off, then the NO alarm contacts of all the master
units have to be cabled in parallel. An example is given in
for 2 master filters.
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 63: 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
