Control of innovative, electric rope balancer!

ZASCHE handling turned to Delta Industrial Automation to draw upon their expertise in motor control solutions.

Handling systems are an essential tool across a range of industries, from manufacturing and metalworking to automotive and railway. Personnel must frequently lift and maneuver heavy or awkward loads, then place them with utmost accuracy and care. ZASCHE handling has been focused on this challenge since the 1990s, helping its customers fulfill ergonomic requirements for their staff, such as the EU’s Machinery Directive 2006/42/EC . For many years, the industry has relied upon pneumatic rope balancers to handle and position loads with precision. However, the compressed air required is not always available and, in some cases, is even prohibited.

To meet this market need, ZASCHE handling developed a fully electric rope balancer. With customer expectations aligned to the performance of pneumatic solutions, this electric implementation had high expectations to fulfill. Not only should its performance be comparable with existing products, it would need to be quieter, consume less energy, and have an even simpler maintenance regime.

Such devices can lift loads of up to 100 kg and offer a stroke of 2000 mm. Additionally, single-hand control is expected for fatigue-free operation, while motion must be both smooth and responsive. Perhaps the most challenging aspect of such equipment is limiting motion as the device moves from heavily loaded to unloaded. With many facilities integrating Industry 4.0 technologies, easy integration with CANopen networks was an additional requirement. Features such as Safe Torque Off (STO) and no-drop when the brake was released were further critical aspects of the design for ensuring operator safety.

ZASCHE handling turned to Delta Industrial Automation to draw upon their expertise in motor control solutions. A three-phase induction motor requiring field-oriented control (FOC) had been selected to power the rope balancer that would be powered from a single-phase, 230 V supply. An encoder integrated into the gearbox, providing 1024 pulses per revolution (ppr), formed an essential element of the balancer’s precise control implementation. The need for vibration-less motion from the motor drive proved challenging at the highest and lowest speeds due to operators expecting the same responsiveness at high loads as they do at low loads.

After careful review of the requirements, Delta proposed the MH300 Series of high-performance, heavy-duty micro drives. The vector control implementation matched the selected motor optimally. Furthermore, thanks to its 40% size reduction over previous generations of the drive, it was an excellent fit for the rope balancer and contributed to its low overall weight. The integrated PLC provided the flexibility required to optimize the motor control precisely to the needs of the application. The USB port built into the drive ensured the customized firmware of the PLC could be updated with ease, enabling rapid iteration and testing of software improvements to the design’s closed-loop controller. This 230 V, single-phase micro drive also delivered the requested built-in support for CANopen and a Class A (C2) EMC filter.

Rope balancers are subject to wildly changing loads, so drive solutions must be heavy-duty. The MH300 Series provides a 150% overload capability over 60 seconds and 200% over 3 seconds. To support the compact design requirements, the integrated STO, compliant with EN 61508 SIL2, replaced the multiple contactors typically needed for emergency stop implementations. Coupled with a Safety Relay, the safe release of the rope balancer’s brake could be guaranteed. Safe hold in the event of power loss was also implemented.

Precise control is at the core of such applications, requiring the micro drive to accurately monitor the motor’s rotor position. Thanks to the modular approach used, the MH300 Series could be interfaced with the selected encoder using one of the available PG Cards that are easily inserted in the available Options Slot. Combined with the ability to program upper and lower control limits into the MH300, this also helped reduce overall design complexity.

Innovative products, such as the Z-BE electric rope balancer from ZASCHE handling, are challenging to develop, especially when expectations are already set so high by existing solutions. However, thanks to the close cooperation with Delta Industrial Automation, operators and facilities managers now have access to an intuitive-to-use, safe, accurate, low-maintenance, and, above all, electrically efficient alternative to pneumatic rope lifters. “The selection of the MH300, with its simple configuration, integrated CANopen, and modular approach, has enabled us to deliver our product with the safe control and precision our customers expect,” said Günther Rieck, Electrical Engineer at Zasche. 

Dr. Jörg Eidam, CTO at Zasche added, “We also value the technical insights and support provided by Delta at every stage of development.” 

Holger Friedrich, Sales Manager at Delta also highlighted that: “The compact and rugged MH300 Series was designed with exactly such applications in mind. It has been a pleasure to support ZASCHE handling in bringing their application successfully to market.”

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