According to SEW-Eurodrive Strategic Marketing and Product Manager, Darren Klonowski, decentralised architectures bring drive control and execution closer to the application, delivering increased flexibility and productivity to the factory floor. Here, frequency inverters are field-mounted alongside the geared motors, and controlled by a decentralised PLC or gateway acting as an interface to a fieldbus-connected supervisory PLC.
"Decentralised drive systems deliver drive and control components closer to the machine, greatly reducing the 'real-estate' requirement in the central control cabinet," he said. "Moreover, they permit a dramatic reduction in installation, material and maintenance costs associated with wiring inverters back to the central control cabinet. Individual cable runs are shortened in a decentralised control system, as high-voltage field wiring is daisy-chained between devices while sensor and actuator connections are localised to the local I/O blocks. Traditional control cabling is eliminated because the communication between machine-based PLC or gateway and the supervisory PLC is achieved through a single fieldbus connection."
SEW-Eurodrive's flexible decentralised solutions incorporate the company's proven PLC/gateway-MOVI-PLC-its MOVITRAC LTE version B frequency inverter and geared motor range. The MOVI-PLC/gateway supports a wide array of external fieldbus communication protocols, allowing it to be incorporated into a broad range of vendor-specific system architectures. The MOVITRAC LTE version B offers similar versatility, permitting easy mechanical and electrical installation. The IP55 enclosure-with an integrated mains isolator-enables field-mounting of these frequency inverters in close proximity to the load-driving motor.
Klonowski explained that one of the key differentiators of SEW-Eurodrive's decentralised drive solution-set is the provision of a CAN-based system bus gateway. "The gateway we use to communicate to the fieldbus is extremely straightforward to configure-significantly more easily than most other industry offerings," he said. "Furthermore, SEW's CAN-based system bus is faster than the industry-standard RS485."
SEW-Eurodrive's modular decentralised solutions are built on the company's long-standing expertise in distributed control technology. OEM's and end-users can now benefit from cost reductions resulting from recent technological developments in frequency inverter design and advancements in add-on components.
"Cost savings can be further realised through a reduction in size of the main control cabinet, which no longer has to house the frequency inverters-now field-mounted close to the gearmotors," said Klonowski. "This set-up also simplifies fault-finding and troubleshooting activities. Typically, for conveyor and pump applications-where it is necessary to control the speed and stop/start the unit-decentralised drive solutions will provide significant ongoing cost savings, when compared with conventional centralised control systems."
