Winder program features 61Web lossThe Web loss detection function enables the drive to detect an occurrence of webloss (web break, wire break or cable breakdown) in the tension control modes fromthe following conditions:• In the Open loop tension control mode, the drive detects web loss when thedifference between the actual line speed and final speed reference together withoverspeed reference goes below the defined level. This happens because, incase of a web loss, the motor speed rushes from the line speed to overspeedreference and the speed difference decreases to zero.• In the other tension control modes, the drive detects web loss when the tensionfeedback from the web (tension or dancer position) is less than the web loss limitset by the user.The user can also define a time delay for the web-loss function to trigger a drivealarm or fault.SettingsParameter group 81 Winder safety (page 449)Virtual rollVirtual roll function offers an additional method for diameter estimation. It allows touse an encoder feedback to count how much material is delivered on a roll, and toassume the actual diameter and the roll driven speed. The encoder can be placedeither on a pulley connected to the line surface, or directly on the motor driving theroll.See the below virtual roll control chain diagram.SettingsParameter group 82 Virtual Roll (page 453)
