Physical Characteristics
152607 1–7
Main Inverter Enclosure
The PV225S Main Inverter Enclosure is NEMA-3R rated and contains the po wer
distribution panel, the converter control unit (CCU2), and the powe r electronics
matrices. Also found within the Main Inverter Enclo sure are some of the system
protection devices (such as the sense and control po wer fuses).

Power Distribution Panel

This panel contains many of the El ectromechanical, protective, and control po wer
components necessary to support the opera tion of the PV225S.

Converter Control Unit (CCU2)

The CCU2 is a Digital Signal Processor (DSP) based contro l board that performs
numerous control and diagnostic functions associated with PV225S operation. Its
most significant tasks are control of PV225S el ectromechanical components and
power electronics converters, signal co nditioning for high voltage signal inputs
and communication with the Universal Front Panel Contr ol Unit, and system
sensors. The CCU2 also contains the necessary DC po wer supplies to support its
operation.

Power Electronics Matrices

The power electronics converters are loc ated at the top of the PV225S main
inverter enclosure. Both the left and right matrices a re comprised of six switching
transistors (IGBTs), transistor gate drive electronics, a laminated power bus, DC
capacitor bank, and an aluminum extrusion heatsink with a cooling fan. The fans
are located above each matrix heatsink.
The PV array is tied logically to the m atrices DC bus within the DC interface
enclosure. The embedded CCU2 control unit manages the transf er of power
between the DC bus and the utility grid by sending digit ized gating signals to the
IGBTs for producing a high-fidelity, sinusoidal output.
Inductor Enclosure
The Inductor Enclosure is NEMA-3R rated. It contains the ne cessary filter
components to ensure the PV225S line current meets IEEE- 519 (1992, Standard
Practices and Requirements for Harmonic Control in Electrical Power Systems)
and UL 1741 (2001, Static Inverters and Converters for use in Indepe ndent Power
Systems) harmonic distortion requirem ents. Mounted on both the right and left
side of the lower enclosure are inductor fans to allow cooling of the line filter
components within. This enclosure also serves as the mounting base for the
PV225S Main Enclosure.