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AC Log Carriage Drives
General
The Salem AC carriage drive is a complete system including a high performance AC induction motor coupled to a gear reducer driving a cable drum, all mounted on a common steel base. The control system consists of a state-of-the-art flux vector drive controller working in conjunction with a Programmable Logic Controller (PLC) to provide maximum flexibility and performance. A no-nonsense operation control /status panel and heavy duty control handle round out the package as truly being designed for the sawmill environment. The system is designed to provide high production, quick responsiveness, energy efficiency, and ease of maintenance.
Motor
Is a high-performance AC induction servo motor specifically designed for the continuous reversing parts of a log carriage. It is a drip proof force ventilated motor with mounted blower and filter assembly, encoder, and three internal thermostats. The motor rotor is of a low inertia design resulting in a greater portion of the input power being used to drive the carriage thus further improving system efficiency. The motor stator and rotor construction allow for a peak overload capability of nearly 200% of full load torque to provide the high performance needed in a carriage application. |  |
Controller
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Precise motor control is accomplished by using the latest generation in closed-loop vector control technology. The drive is coupled to an IGBT-based Active Front End (AFE) module which efficiently returns braking energy from the motor back to the AC power line, thus eliminating the need for dynamic braking resistors. The AFE ensures that current and voltage are in phase, maintaining a 1.0 power factor and minimal harmonic distortion (meeting IEEE 519). All components are conservatively sized for each application to ensure a long, trouble-free parts life. A PLC is incorporated into the drive system to provide additional program flexibility, network communication, and status annunciation to supplement the drive's extensive built-in diagnostic capabilities. |
Operator
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Control is provided through two convenient control devices mounted in the saw cab. The first is a small NEMA 12 enclosure containing all necessary control devices and status indication for normal operation and troubleshooting. Also included are remote network ports providing communication to the drive system so that tuning and extended diagnostics can be performed from the sawyer's chair. The second device is a custom designed, heavy-duty speed control handle driving a non-contact absolute encoder and redundant safety switches for additional stopping protection. User-configurable variable sensitivity allows for individual "feel" to be applied to carriage motion. The handle is mounted on a rugged adjustable height pedestal and can be adapted to various types of sawyer's handles. |  |
Gearbox
Motor torque is transmitted to the cable drum through a standard parallel shaft double reduction gearbox sized conservatively to ensure a long, trouble free parts life. Exact ratios are determined for each application to optimize throughput and motor performance based on individual sawing requirements. Double engagement couplings are use on both the input and output shafts to minimize downtime in the event partss is required. An optional failsafe air/hydraulic caliper disk brake is offered to provide maximum stopping protection.
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