Manual Mode; Taper Tension; Inertia Compensation; Hold Level Control - Magpowr DIGITRAC
2 Instruction Manual

6.11

MANUAL MODE

Switch to MANUAL mode at any time using SHIFT,.
LEVEL screen. Switch back to AUTOMATIC mode using SHIFT,
6.12

TAPER TENSION

Taper tension is used on rewinds to make better rolls by reducing full roll tension compared to core tension. Use
PROGRAM-CONFIGURE to select TAPER TENSION. Input the CORE DIAMETER and FULL ROLL
DIAMETER. TAPER PERCENT can now be entered on an operator screen. Percent taper is defined as the
percent decrease in tension from core to full roll.
If a diameter input is not used the DIGITRAC 2 estimates diameter. More accurate results are obtained if a
diameter input is provided. See Section 6.2. Either way, diameter must be calibrated using PROGRAM-
CALIBRATE-DIAMETER. When calibrating diameter, set TAPER PERCENT to 0.
6.13

INERTIA COMPENSATION

Extra torque is often needed to help stop large unwind rolls. STOP MULTIPLIER is available to increase the
output as a multiple of the present running torque. If better stopping results are required, they can be attained by
selecting INERTIA COMP using PROGRAM-CONFIGURE.
The DIGITRAC 2 asks for information needed to calculate the inertia of the unwind roll. The DIGITRAC 2 needs
this information to calculate the inertia and required stopping torque as the roll diameter changes.
If a diameter input is not used, the DIGITRAC 2 estimates diameter. More accurate results are obtained if a
diameter input is provided. See Section 6.2. Either way, diameter must be calibrated using PROGRAM-
CALIBRATE-DIAMETER. You must select INERTIA COMP before calibrating diameter.
Diameter must be calibrated while the machine is running, so required stopping torque can be
calculated.
The DIGITRAC 2 must also know roll width to calculate roll inertia. A new screen now appears in the operator
loop to input this information when INERTIA COMP is selected.
6.14

HOLD LEVEL CONTROL

During normal automatic operation the output changes to correct for changes in DESIRED TENSION, roll
diameter, etc. During the STOP TIME the DIGITRAC 2 is still in automatic mode, but the output is momentarily
changed by STOP MULTIPLIER or INERTIA COMP to help stop the unwind roll. At the end of STOP TIME the
DIGITRAC 2 switches to HOLD mode. In HOLD mode the output is fixed at the HOLD LEVEL. PROGRAM-
CONFIGURE can be used to set HOLD LEVEL CHANGES WITH TENSION and / or HOLD LEVEL CHANGES
WITH DIAMETER.
6.15

OPTIMIZE METHOD

You should normally select PI (Proportional-Integral) for tension control applications. OPTIMIZE changes P and
I to give optimum response. For special applications PID (Proportional-Integral-Derivative) can be selected
using PROGRAM-CONFIGURE.
The output is now fixed at the level set in the MANUAL
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