Varispeed recently partnered with a prominent local cable manufacturer to upgrade an existing, outdated control system.
“This customer had been looking to upgrade the control system on a particular machine for quite some time,” explains Jason van der Merwe, branch manager at Varispeed’s KwaZulu-Natal branch. “The previous system was a mixture of hardwired relay logic and PLC control. It was out of date with limited diagnostic capabilities and did not offer full synchronisation during slowing or stopping.”
In terms of the application, van der Merwe says that this system was used on a lay-up machine consisting of six rotating payoffs and a carriage. The machine winds and twists multiple cores together to create specialised multicore cables.
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,” adds van der Merwe.
The upgraded system offers an 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.”