Working Principles

Figure 2-7 Schematic diagram (The components in dotted boxes are optional. Either a PoE module or a switch can be configured.)

The SACU communicates with devices in a PV array over RS485, MBUS, or Ethernet.

When the SACU communicates with the inverter over MBUS, log in to the embedded WebUI of the SmartLogger3000, choose Monitoring > MBUS > Network Settings, and set Networking to Enable (default value). When the SACU communicates with the inverters over RS485, set Networking to Disable. For details, see the SmartLogger3000 User Manual.

• RS485 communication mode
  Figure 2-8 RS485 communication mode
  
  • All SACU models support the RS485 communication mode.
  • The SmartLogger connects to the transformer station, power meter, inverter, PID module, MBUS CCO module, and other devices that support RS485 communication over COM ports.
    • The SmartModule is installed before delivery only for the SmartACU2000D-D-03.
    • The figure displays only major components and cables, and is for reference only.
• MBUS communication mode
  Figure 2-9 MBUS communication mode
  
  • If a double-winding transformer is used, use the SACU that supports the access of one MBUS route.
  • If a double-split transformer is used, use the SACU that supports the access of two MBUS routes.
  • The SmartLogger has embedded MBUS. It connects to the inverters that support MBUS communication over the three-phase AC power cable.
  • In the SACU that supports the access of two MBUS routes, the MBUS CCO module connects to the inverters that support MBUS communication over the three-phase AC power cable.
    • The MBUS CCO is installed before delivery only for the SmartACU2000D-D-03.
    • The figure displays only major components and cables, and is for reference only.
• Ethernet communication mode
  • All SACU models support the Ethernet communication mode. The cabinet reserves a position for installing an Ethernet switch.
  • The SmartLogger has one 10/100/1000 Mbit/s Ethernet electrical port (WAN), and the SmartLogger connecting to an Ethernet switch has five 10/100/1000 Mbit/s Ethernet electrical ports.

The SACU communicates with the plant monitoring system over a fiber ring network or 4G LTE network.

• Over a fiber ring network
  • All SACU models support a fiber ring network.
  • The SmartLogger connects to the plant monitoring system by optical fibers through an ATB.
• Over a 4G LTE network
  • All SACU models support the 4G LTE communication mode. The cabinet reserves positions for installing the PoE module and PoE SPD.
  • The SmartLogger connects to the plant monitoring system by 4G LTE through CPE.

The PID module factory-installed in the SACU can change the voltage between the neutral point on the AC side and the ground to change the voltage between the positive or negative electrode of PV modules and the ground, so as to prevent PID effect on PV modules.

• If a double-winding transformer is used, use the SACU with one PID module.
• If a double-split transformer is used, use the SACU with two PID modules.