When a global metal recycling organisation was facing challenges with a competing brand of Liquid Resistant Starter (LRS) at one of its Australian plants, CSE Uniserve was approached to supply a solution to improve overall performance and reliability of the plant.
Those with experience will attest to the fact that one of the key drivers of efficiency and output in metal recycling is the shredding process. The existing control mechanism on the customer’s feed roller, saw the PLC monitor stator current as product was fed into the shredder and adjust the electrodes when a rise in current was seen.
The response speed of this approach however, meant the system was predicting how much of a current spike they were going to get. This often resulted in a backing off the electrodes too soon, causing the shredder to slow to about half speed and requiring the motor to do more work to get back up to speed (and while full of product). If backed off too far, this would cause another current spike, and the cycle would repeat until the 4.5MW motor tripped.
Enter the first Australian-built LRS shredder with rotor current control, blending the robustness and reliability of the CSE Uniserve LRS with a brand new control philosophy.
The new approach developed in-house at CSE Uniserve provides a very fast response, allowing the LRS to monitor the rotor current and maintain the electrodes until absolutely necessary – responding reactively instead of predictively, and only adjusting the electrodes when a current spike is in the process of happening. This allows the motor to retain speed, which makes it easier to process the material and requires less time and less energy from the supply to recover. It also means the operator can allow more product into the shredder sooner, resulting in a higher tonnage/hr through the shredder.
Complete site commissioning was just five days including two days of operation performance monitoring to confirm Site Acceptance and that the control method worked as designed. The result is a more efficient, effective and reliable control of the application and one happy customer.