This week I was called in to a paper mill to look at a problem following a drive upgrade. This was an old machine that had one section running in tension control for about 40 years.
The old drive used a dc generator. The new drive was a previously enjoyed digital dc drive.
After the upgrade, the tension regulator was unstable and was left in manual (draw) control. Things remained in this state for several months. Additionally there were problems with stability of the draw and slack take up. The operators were frustrated, and not at all pleased with the upgrade. Threading was difficult and the draw required constant monitoring while running. Shows that sometimes replacing old for new is not the same as making an improvement.
The tension and draw problems were solved with a filter on the analog speed reference. The slack take up was restored with a small programming change in the drive.
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President. Designated Consulting Engineer with Professional Engineers Ontario (PEO). KlassENgineering was incorporated in 1999. Clarence applies 31 years in the Pulp and Paper industry to solving problems with drives for web handling. He has 10 years experience as a drives engineer with GE Canada and 10 years experience with Opcode Systems Inc., a PLC and Drives Systems Integrator. Much of Clarence's experience was gained in onsite installation of new equipment and troubleshooting of existing equipment. KlassENgineering performs Pre-Start Health and Safety Reviews as required by the Ontario Ministry of Labour.
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