Variable Frequency Drive Package for DD Refiner Plate Adjustment: The GL&V Variable Frequency Drive Package includes an Allen-Bradley Powerflex 40 Variable Frequency Drive with an inverter duty gear motor designed to replace the two speed plate adjustment gear motor for your DD Refiner. The variable speed drive allows for improved plate adjustment during refiner operation, which improves the refiner’s responsiveness to process conditions (e.g. flow, consistency) and hence minimizes fiber quality variation.
The traditional plate adjustment gear motor operates with two separate speeds. The fast speed is used to load and unload the refiner quickly whereas the slow speed is used to make small adjustments to maintain the process setpoint as the process conditions change. If the dead band around the setpoint is too small, the gear motor will over-shoot the setpoint and then make another correction resulting in under-shooting the setpoint (a.k.a. “hunting”). “Hunting” can be reduced by increasing the dead band around the setpoint yet this leads to an overall reduction in refining responsiveness.
The operation of the VFD allows the gear motor to automatically vary the speed to maintain the process setpoint. The VFD can load and unload the refiner 25% quicker than a traditional twospeed gear motor. In addition, the VFD maintains the process setpoint up to 93% tighter dead band than with a two-speed gear motor. The tighter dead band allows the refiner to be more responsive to process changes, hence minimizing fiber quality variation.
The GL&V VFD also offers a mechanical advantage to the traditional two-speed gear motor. The GL&V VFD is specially programmed with acceleration and deceleration times that are more gentle on the refiner gearing and shear pins than the traditional two-speed plate adjustment gear motor. When running, the traditional two-speed gear motor operates at full speed and full torque without any ramp up time. In this manner the full torque of the gearmotor is transferred to the gearing and over time can cause wear. By using accel/decel times, the VFD is more gentle on the gearing resulting in increased life of the refiner adjusting mechanism and longer shear pin life. The following is a summary of the benefits and features for the GL&V VFD plate adjustment gear motor:
- A 93% increase in refiner responsiveness, which leads to less fiber quality variation.
- A 25% increase in refiner loading and unloading speed.
- The two speed gear motor starter panel is eliminated.
- Conversion Kits are available for DD®3000 and DD®4000 Refiners.