Deana Fu is senior product manager at Mitsubishi Electric Automation.
What’s the most innovative or efficient motor/drive application you’ve ever seen or been involved with?
Deana Fu, senior product manager, Mitsubishi Electric Automation: We recently worked on a stacker crane for an automated storage and retrieval system (AS/RS). It swiftly transfers packages of fiber cement boards from an immense racking system to workers at a ground level. The boards are more than 12 ft long and weigh 12,000 lb/package. In fact, the specifications for this crane were so demanding, the safety, mechanical and structural analysis was in design for almost two years. The size, shape and weight of the load necessitated two vertical axes and two horizontal axes. We had to have multiple drives per axis working in coordinated motion to make it work. We developed firmware to add horizontal sway control to make sure the load stayed level and dual laser position control of the vertical axis to provide precise positioning measurement in a matter of milliseconds.
The racking system for the AS/RS had to be built around the crane. The crane couldn’t be attached to the top of the building because it could potentially take down the entire building. Multiple points of redundancy needed to be accommodated to meet safety.
Typically, the crane would be controlled by the warehouse control system, but, in this case, the crane was designed as a standalone system. Where most applications would put all the intelligence in the PLC, in this situation all the intelligence was built into the drive to ensure a true representation of where the crane is at all times.
The drive communicated to the main PLC over an Ethernet-based safety network. This was an important part of the design because there were two sources of feedback for the crane: the dual-laser distance sensor and the motor. Both had to be taken into consideration. It made sense to do it in the drive because it simplified the design, which resulted in less programming, better accuracy and improved performance.
This is a great example of how drives are no longer isolated motor controls. Being an integral part of a complete automation system makes drives capable of executing complex control and algorithms. It not only needs to handle heavy loads, but also needs to retain accuracy, share information with an external system and ensure safety of the application.
How have motors and drives benefitted from remote monitoring and connectivity?
Deana Fu, senior product manager, Mitsubishi Electric Automation: Remote monitoring allows for efficiency improvements that were previously not taken advantage of. For example, variable-frequency drives (VFDs) with remote monitoring allow operators to perform actions on the VFD at a distance, such as viewing and setting VFD parameter lists, debugging programs and checking diagnostics, right from the office PC or mobile device.
A plant may deploy hundreds if not thousands of drives, and remote monitoring allows an operations manager to efficiently monitor the status from a single dashboard, staying aware of complications or productivity decreases, collecting data for error analysis and taking immediate action before an issue escalates.
Thanks to this level of visibility, issues are often investigated and root causes are often spotted and addressed early on. There is less potential for unnecessary strain on the motor and reduced risk of operating under overloaded conditions for a long time; and drives operate more efficiently overall. As a result, drives and motors now enjoy a longer useful life before needing to be replaced.
A good example of benefits of network connectivity is found in mining applications. A tunnel boring machine, or mole, undergoes extreme variations in stress across its entire cutter head, as it encounters materials of differing hardness throughout its operation.
If one section of the cutter head hits a hard part of earth and the other section doesn’t, it can create a stress imbalance that can result in motors overheating or being damaged. By using multiple networked VFDs to control the motors of the tunnel boring machine, stress imbalances can quickly be resolved and prevent damage to a motor.
Each VFD stays aware of the stress and workload of the other VFDs and can speed up or down on the fly to alleviate potential malfunction. By slowing down, for instance, when another VFD is working extra hard, the networked VFDs conserve energy and reduce undue wear on machine parts until they move into an area with harder materials and need to speed up.
Lastly, manufacturers are now getting creative at identifying what other useful and actionable information can be harvested from the drives.
Also read: Ease of use dominates motor and drive trends
When will motors and drives become IT-friendly enough that engineers are no longer required for installation and operation?
Deana Fu, senior product manager, Mitsubishi Electric Automation: With added smart features, safety contingencies and more complex networking capabilities, it is difficult to imagine a world where engineers are no longer required for installation and operation. In fact, technicians and engineers may need to develop new skill sets to support some of these advanced features.
Many VFDs can be networked via Ethernet to other automation equipment, factory information management systems or even other VFDs. The advanced capabilities of networked VFDs allow multiple drives to communicate with each other and stay in sync as needed.
Engineers not only need to know how to install and operate the drives in a stand-alone environment, but now they also need to become knowledgeable in the intricacies of network settings, ensuring that the drives are sending and receiving data to the right devices. It goes without saying that manufacturers have the responsibility to ensure that user interfaces are simplified and as intuitive and easy-to-use as possible, allowing most operations to be configurable in a no-code environment, so that system startups can be executed quickly and without delay.
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