Hello All,
We have several conveyors onsite which have a takeup winch to keep the belt tension is a specific band. We get the feedback from a strain guage at the fixed end of the rope and a load pin on the pully closest to the take up winch drum. These two tension feedbacks are averaged which is then used by the control system to adjust the winch in and out accordinly.
The conveyors had only been commissioned for a few months, and we have four of them.
The issue we have is that the two tension feedbacks are different, and the size of the difference varies quite considerably. The load pin is generally higher then the strain guage, which to me makes sence as the tension is applied from the drum, and you would expect to lose efficiency over the 13 pulleys the ropes go through (please note that im a elec eng) before it gets to the fixed point where the strain guage is.
However the difference is sometimes only 4% or less, often the difference gets to 13%, and in some cases the variance can get to 20%. Often these changes in the differrence between the two tensions occur when the winch has moved. Sometimes is load pins tension which changes, sometimes the both diverge equally but oppisote. I have attached a trend to help explain.
I guess my questions are is 20% and resonable variance in the tension accros the length of the rope. why does this difference vary, is it just the nature of the system with so many pulleys. under each winch movement dooes each pulley just end up with a differnent loss due to a binding or similar?
The pulley are 800mm on the fixed end of the trolley and 1000mm on the moving end, the rope would be 30 or 40mm (cant find a spec for it at the moment).
Thanks
Allan
We have several conveyors onsite which have a takeup winch to keep the belt tension is a specific band. We get the feedback from a strain guage at the fixed end of the rope and a load pin on the pully closest to the take up winch drum. These two tension feedbacks are averaged which is then used by the control system to adjust the winch in and out accordinly.
The conveyors had only been commissioned for a few months, and we have four of them.
The issue we have is that the two tension feedbacks are different, and the size of the difference varies quite considerably. The load pin is generally higher then the strain guage, which to me makes sence as the tension is applied from the drum, and you would expect to lose efficiency over the 13 pulleys the ropes go through (please note that im a elec eng) before it gets to the fixed point where the strain guage is.
However the difference is sometimes only 4% or less, often the difference gets to 13%, and in some cases the variance can get to 20%. Often these changes in the differrence between the two tensions occur when the winch has moved. Sometimes is load pins tension which changes, sometimes the both diverge equally but oppisote. I have attached a trend to help explain.
I guess my questions are is 20% and resonable variance in the tension accros the length of the rope. why does this difference vary, is it just the nature of the system with so many pulleys. under each winch movement dooes each pulley just end up with a differnent loss due to a binding or similar?
The pulley are 800mm on the fixed end of the trolley and 1000mm on the moving end, the rope would be 30 or 40mm (cant find a spec for it at the moment).
Thanks
Allan
