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Identificazione: MD-AL-GI-00
Rev. 4.0 del 31.01.18 - Applicazione: GID
Manual of 07/06/2019 Rev. 1.1 “User Manual for 20K-33KTL”
2.2.
Description of functions
The DC voltage generated by the PV modules is filtered through the input board before entering the power
board. The input board also has the function of measuring the insulation impedance and the DC input
voltage/current. The power board converts the DC power into AC power. The current converted into AC is
filtered through the output board and is then fed into the grid. The output board also has the function of
measuring the grid and GFCI voltage/current and of piloting the output insulation relays. The control
provides the auxiliary power supply, controls the operating status of the inverter and shows it on the display.
The display also shows the error codes when the inverter is not functioning properly. At the same time, the
control board can activate the protection relay in order to protect the internal components.
Operating principles
The DC switch disconnects the internal circuits from the DC input for maintenance purposes.
The control board of the strings measures the input current and voltage, analyses the functioning
state of each PV string, and if anomalies are found on the strings, alerts the user to perform the
relating control and maintenance operations.
Electromagnetic filters (EMI) at the input and output filter the electromagnetic emissions of the
inverters to ensure that they meet the electromagnetic compatibility requirements.
The input board measures the insulation impedance, voltage and current of the various strings; it
also manages the algorithm of the maximum power point algorithm (MPPT) to maximum the power
generated by the photovoltaic strings.
The DC-AC conversion circuit converts the DC power into AC power and feeds it into the grid,
complying with requirements of local regulations.
The insulation relay disconnects the inverter from the electrical network when the grid or the
inverter fails.
The communication board allows the inverter to communicate via RS485 and Wi-Fi (optional); the
user can access all operating data via web portal from a PC and via APP.
