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Installation and Operating Instructions
V03
5.4.4 Residual current protection
The inverter is equipped with an all-pole sensitive residual current monitoring unit
(RCMU) with an integrated differential current sensor which fulfills the requirements
of DIN VDE 0100-712 (IEC60364-7-712:2002).
Therefore an external residual current device (RCD) is not required. If an external RCD
needs to be installed because of local regulations, a RCD type A or type B can be
installed as an additional safety measure.
The all-pole sensitive residual current monitoring unit (RCMU) detects alternating and
direct differential currents. The integrated differential current sensor detects the
current difference between the neutral conductor and the line conductor. If the
current difference increases suddenly, the inverter disconnects from the grid. The
function of the all-pole sensitive residual current monitoring unit (RCMU) has been
tested in accordance with IEC 62109-2.
Rating of the external residual current device
•
If an external residual current device (RCD)
is required in a TT or TN-S system,
install a residual current device which trips at a residual current of 100
mA or
higher.
•
For each connected inverter, a RCD with 100mA rated residual current has to
be provided. The rated residual current of the RCD must be equal to at least
the sum of the rated residual currents of the connected inverters. That
means that, if, for example, two transformerless inverters are connected, the
rated residual current of the RCD must be at least 200 mA.
