Case Studies, Maintenance, Maintenance Products, Plant & Equipment

Drive train efficiency yields solid gains

The implementation of efficient drive systems will become a priority for the quarry industry in the future. A new generation of drive technology, combined with a ?total systems? approach to optimising efficiency, promises to yield huge savings for all motor-driven industrial activities, including conveyors and crushers.

SEW-Eurodrive?s industrial gears national product manager Ian Tribe has said efficiencies in a drive system are subject to a ?multiplying effect?. That is, the efficiencies of each element in the complete drive train ? from motor and electronics to gear unit, belt or chain ? multiply to determine the total power transmitted. Thus, poorly designed drive equipment or an excessive number of components in the drive train severely compound overall losses.

This fact is especially relevant to quarries which still utilise legacy V-belts or chains and sprockets. ?In the past, there were not many gear ratios available and the systems were designed to provide a flexible means of speed adjustment,? Tribe explained. ?But they certainly weren?t efficient.?

Today, customers have access to more gear ratios and efficient, flexible drive systems can be achieved with a single customised gear unit. Through this ?close-coupling?, the number of drive elements and overall transmission losses are lower and the system has no exposed moving parts and requires no guards, making it safer to maintain.

For SEW-Eurodrive, numerous technological innovations are behind the preference for its gear units over other speed reduction forms. Modularity allows a large number of possible gear ratios. Quality and careful gear design are critical, with inefficient gear configurations such as single-stage worm gears avoided.

The focus on total drive train efficiency necessarily extends to motors. SEW-Eurodrive continues to expand its DR motor series by releasing the DRC motor range, with its efficiency surpassing the highest efficiency IE4 class.

However, as Tribe has pointed out, the benefits of high efficiency drive equipment can be seriously undermined if it is not matched to the application requirements. He said motor efficiency is best when operating between three-quarters and full load. The mistake some users make is to select oversized equipment for extreme demands, meaning the motor runs at half-load or less.

?The ?guess a size and double it? approach means the customer will pay more through the life of the equipment,? Tribe explained.

The alternative is accurate selection and sizing of equipment. SEW-Eurodrive engineering staff perform calculations to ensure each drive element is finely tuned to meet the load requirements, with the motor running at close to full power. Increasingly, SEW-Eurodrive customers are seeking a customised drive package, in which all drive elements, including motor, brake and gear unit, are mounted to the same base.

Finally, efficiency gains and greater control over speed adjustment can be achieved through use of drive electronics. Tribe said inverter technology is becoming more affordable, as evidenced by the popularity of SEW-Eurodrive?s MOVITRAC LTP B series. He added this inverter series is particularly suited to the industry, being available in a robust IP55 enclosure for the complete power range.

?With the inverter, you?re getting better motor control, enabling electronic adjustment of the process speed. The power factor is always close to unity, so even when partially loaded, you?re saving energy.?

Source: SEW-Eurodrive


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