Cabling Of Alarm Functionality - ABB PQFS Installation, Operation And Maintenance Instructions

6.12.2

Cabling of alarm functionality

An alarm represents an error condition that makes the filter trip.
Two types of error conditions exist:
Two ways to cable the alarm functionality exist:
Filter state
Disconnected from the supply
Filter (auxiliaries) connected to
the supply, no error present
Filter (auxiliaries) connected to
the supply, error appears
Filter (auxiliaries) connected to
the supply, error disappears
58 Electrical design and installation ç Manual Power Quality Filter PQFS
· External error condition: These are conditions that are imposed on to the filter
from the outside world. Consider the example of the network voltage that
increases well above the filter safe operation level for a certain time. In that case
the filter will disconnect from the network reporting a network over voltage. When
the network voltage returns to a normal level however, the filter will reconnect to
the network and continue filtering providing that the same problem does not
occur systematically.
· Internal error conditions: These are error conditions that are reported by internal
controls of the filter itself. They may indicate an internal filter problem.
· The PQF-Manager alarm outputs located at the bottom right side (when looking
at the PQF-Manager from the rear) are triggered (return to default position)
whenever:
a permanent internal or external error condition is present. In order to
o
avoid transient switching of the contacts, the error has to be present for
3 minutes before the alarm relays are activated.
no power is supplied to the filter
o
Table 24 further down this section gives an overview of all the error conditions
that lead to the alarm contact being triggered. Two alarm contacts exist, one
being of type 'normally open' (NO) and the other of type 'normally closed' (NC).
The alarm contacts are
free of potential
o
rated for a maximum of 250 Vac/1.5 A or 30 Vdc/5 A. When using a 24
o
Vdc power supply, a minimum current of 25 mA should be drawn by the
circuit connected to the alarm contact.
Table 22 shows the status of the alarm contacts for different operation modes of
the filter.
Table 22: Status of the alarm contacts for different filter operation modes
Figure 51 shows an example of an alarm contact-cabling scheme using the NC
alarm contact. Using this scheme the bulb B will be on when the power supply to
Normally open alarm
contact state
Open
Closed
Opens when error present for
3 minutes
Otherwise, remains closed
When open before, closes
when error disappears
When closed before, remains
closed
Normally closed alarm
contact state
Closed
Open
Closes when error present for
3 minutes
Otherwise, remains open
When closed before, opens
when error disappears
When open before, remains
open