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by Bassam Dib, B.ing, Senior Analyst
Failure of a load cell cannot be detected based on its measurement. In fact, the load control will continuously regulate cylinder pressures to maintain load cell signals on the reference. This failure can be detected by comparing the load cell signal with an independent load measurement calculated from cylinder pressures.
Since the cause of shifts in load cell measurements can be intermittent, it is mandatory to have an automated analysis of pressure and load cell signals on a continuous basis.
Using this approach, we detected an issue with a rider roll load cell measurement on one of our clients’ winder following a shutdown.
Our engineers identified that the drive side cylinder pressure level had increased for the same load reference. This could be the result of load cell damage during mechanical work around the rider rolls.
The documentation we have built on this winder enabled us to recall a similar event that occurred in the past with the corresponding corrective actions. The issue was due to a damaged connector on one of the load cells
A detailed report was sent to the mill with the history of past events and a list of corrective actions. We recommended to verify the physical condition of the drive side load cell and to recalibrate it.
The mill informed us that they found a damage in the load cell wiring close to the connector and that they will replace the cable.
Following the repair work, we sent a report with supporting graphs confirming that this issue was resolved.
On many winders, the rider roll load is controlled in closed loop using load cells. Several events can cause load cell measurements to shift or drift, modifying the effective load level, thus impacting roll quality and stability.
To prevent such situations, load cell measurements should be automatically verified on a continuous basis.
Early detection and reporting of this issue allowed the mill to take corrective actions on a situation which could have led to roll defects or created roll instability.