73Installation
EN
5.7 Operations preliminary to the connection of the PV
generator
WARNING – B In order to safely perform the preliminary operations before the connection to
the PV generator, the connection of the ground protection cable (10)/(28) to the wiring box is
mandatory.
5.7.1 Checking of leakage to ground of the photovoltaic generator
Measure the voltage present between positive and negative pole of each string respect to the ground.
If a voltage is measured between an input pole and ground, it may be that there is a low insulation
resistance of the photovoltaic generator and the installer will have to carry out a check to solve the
problem.
FORBIDDEN – H Do not connect the strings if a leakage to ground has been detected, as the
inverter might not connect to the grid.
NOTE – D Refer to “Verification of ground leakage” paragraph on this manual to know how to
verify the leakage to ground of the photovoltaic generator.
5.7.2 Checking of string voltage
Measure the voltage present between positive and negative pole of each string using suitable equipment
(1500V rated voltmeter).
If the open circuit voltage of the string is near the maximum value accepted by the inverter, consider that
low ambient temperatures cause an increase in the string voltage (different according to the photovoltaic
module used). In this case it is necessary to carry out a check of the sizing of the system and/or a check
on the connections of the modules of the system (e.g.: number of modules in series higher than the design
number).
ATTENTION – A Input voltages higher than the maximum absolute value accepted by the inverter
(see technical data table) may damage the equipment.
5.7.3 Checking the correct polarity of the strings
WARNING – B These activity must be carried out with the appropriate PPE (overall resistant
to electric arc, dielectric helmet with visor, insulating gloves class 0, Protective overglove in
leather EN420 – EN388 , Safety shoes).
WARNING – B The reverse polarity can cause severe damage and electric arc hazards! In case of
reverse input strings do not disconnect them while under load and do not turn the DC disconnect
switches (19) to OFF position. Wait until input current are below 0.5A (when solar irradiance
declines at night) and turn the DC disconnect switches (19) to OFF position, disconnect the DC
input quick fit connectors (18) and correct the wrong polarity of the string.
Before connecting any input strings to the DC input quick fit connectors panel (18) the string polarity of
each string have to be checked using suitable equipment (1500V rated voltmeter).
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