Protection concept
The following parameters are monitored
continuously and in parallel by the micro-
controller and displayed on the screen:
· DC overvoltage (Fault 3)
· Frequency error (Fault 4)
· Overheating (Fault 5)
· Grid undervoltage, 1-phase (Fault 6)
· Grid overvoltage, 1-phase (Fault 7)
· Grid undervoltage, 3-phase (Fault 8)
· AFI error (Fault 9)
· Insulation error (Fault 10)
· DC feed (Fault 11)
· Isolated operation (Fault 12)
· Grid overvoltage, 3-phase (Fault 13)
· Surge error (Fault 14)
· Grid voltage 10-minute average value
> 10 % U
NOM
(Fault 15)
98
In the event of a fault, the conversion is
blocked immediately and the grid relay is
isolated. An alarm relay with floating
output is activated (not for Fault 6).
In addition, the following protective
devices are provided on both grid and
PV generator side:
· Grid-side
varistors
Protect the power semiconductors from
high-energy, time-limited voltage spikes
on the grid and provide for a reduction
of energy in the throttle in the event of
grid disconnection.
· Generator-side
varistors
Thermally monitored varistors provide
protection against atmospheric overvol-
tages (e.g. due to remote strikes during
storms).
