Leesona Winder Controller
LWC-392

Leesona yarn take-ups such as the 968 traditionally used the Saftronics CA-246-2 circuit board as the DC drive to power the spindle motor. Operational limitations and reliability issues have prompted the development of a state-of-the-art replacement.

The LWC-392 is the functional replacement of the CA-246-2 and other early drives. It provides features and improvements not found on any other drives. The LWC-392 is a complete winder controller including these features:

Graduated-current, soft-start to reduce machine wear and tear from motor start surge

High-performance, current-protected motor armature drive

High-precision temperature and supply voltage compensated motor field current regulator

Stable preset speed control for accurate and consistent string-up

True spindle speed control instead of older torque control method

High-performance compensator arm control for consistent yarn tension utilizing the patented Selectronics Regulated Setpoint Convergence™

Faster response preset-to-wind transition control for smooth and gentle string-up

Zero spindle speed detection and isolated contact output for brake and doff control

Adjustable maximum armature voltage to eliminate the possibility of spindle overspeed

Auxiliary run and wind opto-isolated outputs for external monitoring and control of functions

Direct armature connection option to eliminate the need for motor-starter relay for greater reliability

Opto-isolated interface inputs for external precision preset controller to allow extremely accurate preset speed setting of multiple positions from a central location

Interface port for host computer control and a myriad of special functions available from Selectronics

Extreme reliability – two-year warranty

OPERATION

The operation of the LWC-392 is similar to the CA-246-2 with a number of improvement exceptions. When the START switch is activated the current delivered to the spindle motor is linearly increased from zero over a controlled "ramp". This provides a soft-start improvement over the CA-246-2, which delivered an instantaneous current surge that adversely stressed the motor’s brushes electrically, and all the drive train mechanically.

When the compensator arm starts to rise from the yarn "string-up" position the LWC-392 immediately transitions to "wind" and begins to decrease the spindle speed to synchronize with process speed. This provides a more controlled and gentle string-up than the CA-246-2 which only transitions to "wind" after the arm passes the normal running position (more than half-way up the arm’s movement range). This also allows using less preset overspeed for gentler yarn treatment.

While winding is proceeding the response of the spindle motor to the yarn speed is greatly improved with much tighter control of yarn tension. This is the result of the patented Selectronics Regulated Set-point Convergence™ that provides an enhanced PID scheme. No variation in the compensator running position from slow to fast process speed or empty to full packages guarantees tension consistency.

Motor temperature affects its field coils’ resistance. To ensure consistent pot-controlled PRESET SPEED the current through the field must be compensated for temperature and incoming supply voltage fluctuations. The LWC-392 maintains .1% (one-tenth percent) tolerance to assure stable preset speed. The motor armature current is limited to a safe value. Starting current is controlled to provide gentle start-up. If the spindle is subjected to stall or excessive drag at any time causing current limiting then the LWC-392 will shutdown after a grace period of ten seconds.

The maximum armature voltage, and hence the maximum spindle speed is limited. If desired an adjustment (VL) on the LWC-392 allows the technician to set this for a maximum spindle speed slightly above the fastest preset speed ever needed. This assures that spindle overspeed will never occur and protects the machine’s mechanics as well as the package.

During winding the LWC-392 controls spindle speed not torque as on the CA-246-2. This means that machine friction, drag and inertia do not dilute the control process. This improvement extends motor life while improving winding consistency.

OPTIONS

A number of standard and custom options are available from Selectronics for the LWC-392 to provide functions such as:

dynamic braking featuring "soft-brake" high-performance graduated

deceleration (eliminates need for braking resistor)

metered length control for consistent package size

yarn tension control custom profiled over the package build

package compaction control (spindle-against-roller-bail pressure) that is custom profiled over the package build

precision preset speed programming

wind ratio control providing variable and step changes in helix angle

historical data reporting

host computer control

The LWC-392 is extremely reliable and features a two-year warranty.

For more information about this product, please contact us.