What is the best way to limit current on a conveyor (2hp 3ph) motor to protect belting from jams?

[Marvolus]

I have a plastic modular link conveyor that every time it jams it destroys the belt because the geared 2 hp 3ph motor is too powerful.  I am driving the motor with a Siemens Micromaster 420 VFD.  When I adjust the current max, the frequency changes automatically and proportionally which is not good since I do want to maintain belt speed.  I am told by the belt manufacture that this is just the way it is and that there is no way to overcome this.  I don’t buy this doesn’t seem logical and I have other equipment that if they jam the belt stalls but does not break.  Any thoughts?

[Buechsenschuetz]

There are mechanical clutches available to limit the torque of the drive. However, I have no experience with these and cannot tell you about performance.

[Brian_Beal]

Normally, adjusting the max current in the drive is what you want to do.  I don't know why that drive scales frequency with current.  Normally voltage and frequency remain proportional.  Be sure you are adjusting a max current parameter(or torque if available), and not a rated current that is used to alllow the drive to run properly.  As mentioned, a better alternative may be a torque-limiting clutch or coupling.  Zero-Max and R&W are 2 names that come to mind.