P
AGE
4
OF
15
DGF7 Display
reference
manual, rev. 1, feb 22, 2022
Ground
Fault
Systems
B.V.
2.
F
UNCTIONALITY
2.1
Pushbuttons
The DGF7 Display has two pushbuttons, marked ‘SHOW TRIP’ and ‘RESET’.
With these two buttons a variety of reading and setting options can be performed.
2.1.1
G/F current display
When left untouched (except while in parameter set-up mode, see
), the DGF7 Display will
always return to showing the current flowing to ground, commonly referred to as ‘G/F current’. The user
has two options for showing this current:
Relative format: as a percentage of the G/F Trip Level. The G/F Trip Level is set by means of
dipswitches 1, 2 and 3 on the DGF7-3 base unit. It is the intention that the user checks the ‘%’ box
on the DGF7 Display’s front panel with a marker.
Absolute format, i.e. in engineering units: A or kA. In this mode the DGF7 Display uses the P4
parameter (see
), specifying the CS configuration, to calculate absolute from relative
current. It is the intention that the user checks the ‘A’ or ‘kA’ box on the DGF7 Display’s front panel
with a marker, as is appropriate for the selected configuration. Absolute format is the factory default
setting.
Normally the system shows the G/F current’s actual value, refreshing it every 0,5 seconds. When the
DGF7-3 base unit is in a tripped state, with the fault current removed, the value flashes and refers to the
situation just prior to trip. If the fault current is still active, the actual value will be displayed.
When the G/F current exceeds the system’s measuring range, the display shows
Out
, meaning ‘Out of
range’. Depending on various internal variables, the maximum value that can be represented (whether in
relative or absolute format) before resorting to the ‘Out of range’ indication varies from around 400 to
800 % of the G/F Trip Level.
2.1.2
G/F Trip Level display
The DGF7 Display is able to show the G/F Trip Level Setting (by holding the ‘SHOW TRIP’ button longer
than 2 seconds). All supported configurations are shown in
. For the configurations the user needs
to set internal parameter P4 as is detailed in
2.1.3
Trip code display
Pushing the ‘SHOW TRIP’ button when the G/F current is shown, calls forward the trip code display. If no
trip condition is present, the display shows as
tr:--
. Further operator action lacking, the display will
return to G/F current after 2 seconds. If, on the other hand, a trip condition is present, the format
becomes
tr:xx
in which
xx
is the trip code, indicating the cause of the trip. The
xx
codes are explained
on the front panel of the DGF7 Display. A complete list with more extensive explanations is available in
. Further operator action lacking, the display will return to G/F current after 10 seconds.
Pushing the ‘SHOW TRIP’ button again while the
tr:xx
trip code is on the display makes the display return
to G/F current instantaneously.
Pressing the ‘RESET’ button while the
tr:xx
trip code is on the display, is interpreted as a request to
reset the trip. Both the trip relay and the trip registration will be reset IF possible. During reset action the
display will show a moving dot, then show the
tr:--
format of the trip code and return to G/F current
