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Varispeed recently partnered with a prominent local cable manufacturer to upgrade an existing, outdated control system.

With a rich history spanning 72 years and a staff compliment of 1500 people, this industry leader has a well-established footprint both locally and in Maputo. 

The Project
“This particular customer had been looking to upgrade their control system on a machine for quite some time. The previous system was a mixture between a hard-wire relay logic and a PLC control,” says Jason van der Merwe, Branch Manager at Varispeed’s KwaZulu Natal branch. 

“It was out of date with limited diagnostic capabilities and did not offer a full rational synchronisation during slowing or stopping”.

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In terms of the application, Jason says that this system was used on a lay-up machine consisting of six rotating payoffs and a rotating carriage. “This machine winds and twists multiple cores together to create specialised multicore cables”. 

The Solution
From the PLC and HMI to the Yaskawa GA700 drive programming, electrical drawings and panel wiring, Varispeed handled the entire scope of this project in-house. “We needed to ensure accurate control of this several ton carriage at a constant speed without the need for a large amount of braking resistors that could result in wasted energy and an inefficient system,” he explains.

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The upgraded system offers a 10” HMI communicating to eight Yaskawa GA700 drives via Modbus, and acts as a communication gateway to a PLC via Ethernet IP. “The payoffs operate as digital frequency slaves to the carriage and run in a closed loop vector control method (CLV). The carriage also runs in CLV mode with encoder feedback. The take-up operates as a constant torque device and runs in open loop vector.”