The electrical control of this machine adopts the ABB ACS800 series full – variable – frequency system. This machine is equipped with two sets of mechanisms: the support mechanism and the opening – closing mechanism. Each set of mechanism consists of a frequency converter controlling a motor to form a closed – loop direct control system. The luffing and trolley mechanisms share one frequency converter for switching drive, while the gantry mechanism and the feeder are respectively driven by one frequency converter, and the open – loop scalar control mode is selected.
The overall control system of the machine uses the Siemens S7 – 300 series PLC with a modular structure. The PLC control cabinet communicates with the remote stations via the remote PROFIBUS communication method. It communicates with the central control room through the Ethernet port on the CPU and an external Ethernet switch. In the central control room, the overall operation status of the ship unloader and the status of components can be monitored and controlled.
This machine is equipped with a CMMS system, which can dynamically display the position status of the trolley and hoisting mechanism, equipment fault alarms, the status of various limit switches, and the on – off status of each circuit breaker and contactor in real – time. Three cameras collect video signals through a video capture card into the industrial computer. Users can monitor the signals from the CMMS and cameras on the monitors in the electrical room and the driver’s cab respectively through a frequency divider.
The communication between this machine and the central control room below the machine is achieved through the BreezeNET DS.11 series products of Alvarion Company to realize point – to – multi – point wireless networking.