“There have been VFDs on feeder-breakers for a number of years, but nothing to compare with the advanced integrated capabilities Joy’s Optidrive,”  said Mike Chizmar, global product manager feeder-breakers. Another benefit, Chizmar explained, is underground coal operators would have a single interchangeable drive control system for all Joy equipment, noting that each piece of equipment still retains the software unique to its application.

The device integrates the electrical and mechanical systems and each unique piece of software. Where the motors and drive in the Optidrive system are designed for each other, Joy controls the technology to ensure a compatible system that maximizes use of both components, as opposed to industrial off-the-shelf
components modified for underground mining.

The Optidrive equipped feeder-breakers are available for both underground and surface applications. Interest in VFD with underground feeder-breakers is on the increase and, currently, about 60% of the units going into surface applications are so equipped. All Stamler feeder-breakers with electro-mechanical conveyors are capable of accepting VFDs.

“While the function of the feeder-breaker is the same regardless of application—to break/size material, to convey it and discharge it—its final design may not be as we take into consideration the hardness of the material to be processed and the potential detrimental effects, if any, on the conveyor related components,” Chizmar said. “Other design concerns include customer preferences and associated maintenance.”

According to Joy, the system programming controls the conveyor by two means. Either the conveyor speed can be varied manually through the VFD or the breaker motor amperage readings can slow the conveyor automatically to facilitate breaking of the material being conveyed to the discharge end of the unit. Prior to the arrival of this technology, the only way this could be accomplished with electro-mechanical conveyors would be to install retarding chains or to change sprockets or electric motor RPM, neither of which is really feasible unless the change is to be permanent.

The Optidrive allows an operator to control 25% to 100% of the feeder-breakers rated conveyor throughput capacity, which is particularly important in handling hard materials. By slowing down the flow of material through the breaker, there is less impact and shock load on the breaker components, prolonging life and reducing maintenance. In one instance, in converting from an electro-mechanical conveyor machine to an Optidrive AC-VFD unit, an operator reported reducing the number of shear pin failures by more than 50%.

“With Optidrive these advantages are accomplished with less hydraulic circuits while requiring less than typical hydraulic maintenance. When you can increase efficiency, decrease wear, decrease maintenance and the time it takes to perform it, you allow the operator to spend more time in the coal,” Chizmar said. www.joy.com