P
AGE
5
OF
15
DGF7 Display
reference
manual, rev. 1, feb 22, 2022
Ground
Fault
Systems
B.V.
2 seconds later. Note however, that if at the time of reset a different trip was already lurking, the old trip
registration will clear giving way to the new one, and the trip relay will remain activated without glitches.
Resetting a trip will be refused if the cause of the trip has not cleared yet. In that case the display will
show a 1,5 seconds message ‘---‘, then return to the trip code. Of course one should first clear the fault
in the field that caused the current increase in the first place before resetting, or else the DGF7-3 will
reset its relay and trip out immediately again.
Resetting of the trip relay is meaningless if dipswitches 7 and 8 on the DGF7-3 base unit are set for
Pulsed Relay Operating Mode. However, the registration of the trip behaves as described above in
conjunction with the ‘RESET’ pushbutton.
2.1.4
Trip code display during power down situations
When the DGF7-3 base unit loses control voltage, it sends out trip status information on its datalink
before shutting down. The DGF7 Display receives this information, stores it in memory and then shuts
down itself, which shows by the LCD panel blanking.
Thanks to a built-in backup power source the trip information can be retrieved for at least ten hours after
loss of control voltage. Pressing the ‘SHOW TRIP’ button will bring forward the trip code display as it was
described above, revealing whether or not the system was tripped at the loss of control voltage, and if
so, what was the cause of the trip-out. The information remains visible until the pushbutton is released or
backup power is exhausted.
This feature is useful when pulse tripping a breaker that also supplies control voltage to the G/F
protection system. Especially when several systems control one single breaker (with their relay contacts
in parallel), which prevents the user from having to figure out which of them caused a given trip without
having live systems anymore.
For as long as control voltage remains absent, no other functionality than the one described here is
available.
The memorised trip information will reset automatically when control voltage is restored. If the DGF7-3 is
still in a tripped state, the Display will first show
tr:xx
, than
---
and finally
0,000
or the actual G/F
current value. The previous trip value is lost.
2.1.5
Reset function
The DGF7 Display can be used to reset the DGF7-3 after a trip occurred. A reset will only be granted if
the cause of the trip is not present anymore.
To reset the DGF7-3:
Press the ‘SHOW TRIP’ button to read the trip cause.
Press the ‘RESET’ button to reset the indicated trip, the LCD shows a moving dot, followed by
tr:--
,
then goes back to normal current read-out.
If the cause of the trip is cleared but another one is lurking, then pressing the ‘RESET’ button will reset
the trip indication on the LCD and the new trip code is shown. The relay of the DGF7-3 however will
remain in the trip state, without glitches.
2.1.6
Relay test
Keeping the ‘SHOW TRIP’ button pressed and then pressing the ‘RESET’ button invokes a test, which
switches an AC voltage onto the CS sensor input of the DGF7-3 base unit’s built-in processor. The voltage
is scaled to simulate a residual current of 1,5 – 3 times the G/F Trip Level setpoint. The base unit will trip
on G/F after the delay defined on its dipswitches (plus 0,4 s).
The trip code
tr:00
is called forward by pressing the ‘SHOW TRIP’ button. The ‘RESET’ button can then
be pushed to reset the trip. You cannot reset without first pressing the ‘SHOW TRIP’ button.
