Networked drives keep factories humming

Variable frequency drives (VFDs) have long been the workhorses of the factory floor, controlling the flow of power that moves the machines and the products they make through a manufacturing process.

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But VFDs are no longer being used only in stand-alone silos. Along with most other components in the production process, drives are being connected using communications networks that enable the workforce running a factory to actively monitor the health and productivity of equipment.

“Networking drives allows factories to achieve better quality, control and more cost-effective production,” says Christopher Rhodes, product marketing engineer for Mitsubishi Electric. “Communications from the drives can be transferred in real time, so you can stay on top of any changes in equipment operations.

“Networked drives also enable control of more complex systems, such as multi-pump control or load-sharing,” he adds. “In addition, there are significant cost savings since multiple VFDs can share a PLC or HMI and there’s no need to hardwire a controller’s I/O to each drive. That makes networking a much cleaner and more cost-effective solution.”

Rhodes says there have been major advances in drive technology in the last 10 years, pointing to built-in PLCs, positioning and PID programming functions “These technology improvements mean fewer separate components are needed, so it’s become less costly to build automated systems. Drives can even function as smart slaves in a complete, integrated system.”

While Mitsubishi’s drives and other automation components can be connected to any supplier’s communication network, Rhodes says the company’s engineers recommend the use of CC-Link IE Field since it sets up networking through parameter setting. As a result, there’s no need to write PLC code to handle network communication.

CC-Link uses Ethernet and either standard Cat5e or Cat6 cables, which reduces wiring mistakes. Cat6 cables can future proof a network, according to Rhodes, since they enable 1Gbps data transmission rates. To prevent noise on the Ethernet cables, follow best practices and keep the power supply, motor cables, and control and data cables separated from each other when laid in parallel to each other.

Data transmission and collection, of course, is the whole point of networked drives. Robust networking allows data to be collected from the drives and pushed up to a database or PC for further analysis. The same data can be used for troubleshooting and the predictive maintenance that allows workers to correct problems before they can cause downtime. Networking also allows engineers to remotely monitor the operating status of each drive and read/write parameters to further reduce risks to production schedules.

“By networking VFDs, far more data is available than just start commands, status feedback and general alarms,” he says. “Information, such as a component’s lifetime, motor frequency feedback, specific alarms and whether the VFD is in ‘hand’ or ‘auto’ modes can be monitored and displayed.

“Getting ahead of equipment conditions by using monitoring data to anticipate and prevent problems is crucial to getting more production out of a factory’s assets,” says Rhodes. “It’s a basic requirement today if your manufacturing goals are to improve or maintain product quality, be more efficient and reduce costs.”

Large companies have always been leaders in adopting improved technologies and methods, and that’s still the case with networking drives. But Rhodes encourages small- and mid-sized companies to sit down with suppliers and learn what’s possible.

“The technology issues are easily solved, but the important thing is the data, what it can tell you about your operating equipment, how well it’s functioning and where there are weaknesses. It’s what you can’t see that can hurt you.”

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