Installation manual

Physical Characteristics
153396 Revision D 1–7
This manual is for use by qualified installers only
Power Electronics
The Xantrex GT250 power electronics section contains the converter control unit
(CCU2) and the power electronics matrix. Also found within the power electronics
section are the Hall-effect current transducers, and an internal air circulation fan.
Converter Control Unit (CCU2)
The CCU2 is a Digital Signal Processor (DSP) based control board that performs
numerous control and diagnostic functions associated with Xantrex GT250
operation. Its most significant tasks are control of Xantrex GT250
electromechanical components and power electronics converters,
communication with the Universal Front Panel Control Unit, and system sensors.
The CCU2 also contains the necessary DC power supplies to support its
operation.
Power Electronics Matrix
The power electronics converter matrix consists of switching transistors (IGBTs),
transistor gate drive electronics, laminated DC bus structure, DC capacitors and
an aluminium extrusion heatsink with cooling fans. The fans are located behind
the matrix assembly, and force air down through the heatsink.
The PV array is tied logically to the matrix DC bus within the DC interface section.
The embedded CCU2 control unit manages the transfer of power between the
DC bus and the utility grid.
DC Interface
The DC interface serves as the connection interface between the PV array and
the Xantrex GT250 (see Figure 1-2 on page 1–4 to locate the DC interface). This
section houses the DC disconnect switch and DC contactor. Additionally, the PV
ground fault detection circuitry, DC surge arrestor, solid state relays, and 48 Vdc
power supply are also housed in this section.
WARNING: Shock Hazard
Schneider Electric recommends the installation of PV array disconnect(s) to
ensure personal safety during Xantrex GT250 maintenance. Without PV array
disconnect(s), once the DC disconnect switch (S1) is open, there will be DC
voltage on the DC terminals TB3, TB4 AND TB5 (PV GND). This voltage may be
as high as the open-circuit voltage of the PV array and is limited to 600Vdc per
NEC 690. Use extreme care to avoid these terminals if no PV array disconnect is
installed.