Eurotherm 590SP, Product Manual

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590SP Digital Product Manual
App. M - 12
Appendix M Special Blocks and Application Notes
M
OPEN-LOOP WINDER (CPW)
This configuration provides standard features used in center winder applications including: diameter calculation with
memory and preset, tension and taper, loss compensation, and over/under winding. It can control unwinds or rewinds
for single-spindle and turret winders. The configuration uses four function blocks in the SPECIAL BLOCKS menu;
DIAMETER CALC., TAPER CALC., TORQUE CALC., and SETPOINT SUM 2.
NOTE. This configuration does not support field weakening. A configuration containing field range
compensation is available. Call Eurotherm Drives Customer Support at (703) 471-4565 for detailed
instructions using this option.
A current programmed winder, CPW, provides constant tension center winder control by programming the motor ar-
mature current. The tension control is open-loop, that is, it does not use a dancer or loadcell feedback signal. The drive
maintains constant tension by controlling the motor torque. It keeps the torque proportional to the tension demand and
compensates for changing roll diameter with additional compensation for frictional losses.
NOTE. For accurate tension control, frictional losses must be small (and repeatable) compared to the
torque required to provide web tension.
Description
Figures M.11 and M.13 show typical winder and unwind applications. The diameter is reset before starting a new roll
by using terminal A2, EXTERNAL DIAMETER PRESET, for the diameter setting and C7, PRESET ENABLE, to
select the preset diameter. The drive starts when terminal C3, RUN, is set ON. Setting terminal C4 to ON selects ten-
sion mode. Once the line gets above a minimum speed the diameter calculator begins calculating the roll diameter.
NOTE. This configuration has disabled the JOG function, normally operated by terminal C4. Other
configurations can retain the JOG function.
In tension mode, an overspeed (underspeed for unwinds) is added to saturate the speed loop because the web holds the
winder at line speed. With the speed loop saturated, the drive is current limited by the torque demand. If the web
breaks, the winder increases to the speed loop limits, preventing a runaway.
Terminal C6, OVERWIND, changes the polarity of the torque demand and overspeed for overwinding or under-
winding.
Figure M.10 - Unwind Application