Fronius String Control 250/30 DCD DF - Manual (Page 76)

74
Overcurrent and undervoltage cut-out
General The Fronius String Control 250/30 DCD DF has a cut-out function that interrupts the power
supply in the Fronius Solar Net:
-
in response to overcurrent, e.g. in the event of a short circuit
- in response to undervoltage
Functional princi-
ple The overcurrent and undervoltage cut-out does not depend on the current flow direction.
If the Fronius String Control 250/30 DCD DF measures a current flow of > 3 A or a voltage
of < 7 V while supplying Fronius Solar Net components, the power supply in the Solar Net
is interrupted.
The power supply can be restored automatically or manually.
Safety
Restoring the
power supply au-
tomatically Jumper positions:
A Power supply is restored automati-
cally
(factory default)
M Power supply is restored manually
Jumper (1) must be set to position A in order to restore the power supply automatically.
- After cutting out because of overcurrent or undervoltage, the Fronius String Control
250/30 DCD DF attempts to restore the power supply in the Fronius Solar Net every
5 seconds while the short circuit, for example, is still present.
- The 'PWROK' LED (2) flashes briefly every 5 seconds.
- When the power supply is restored, the 'PWROK' LED lights up green.
If there is no short circuit and the 'PWROK' LED does not light up, the unit has cut out in
response to undervoltage.
In this case, the Fronius DATCOM components must be supplied externally from an exter-
nal power pack.
WARNING! An electric shock can be fatal. Danger from DC voltage in PV mod-
ules.
-
Make sure that both the input side and output side of the device are de-ener-
gised before attaching any connections.
- All connections must be made by qualified electricians.
- Note the safety rules in these operating instructions.
(1)
(2)