I'm currently commissioning a project where we have a couple of dozen powerflex 525 drives. 6 of them run vibrating conveyors - each with one VSD and two vibrator motors. Each drive has two Schneider LRD thermal overloads on the load side to provide thermal protection to the motors.
These overloads are all constantly tripping, even when set 10-20% above the motor nameplate current. The motors are not drawing anywhere near nameplate current.
I figure there must be something about the drive that generates additional heat in the simple bimetallic strip in the TOL's, over and above what the actual current draw would normally cause. Do I have any parameters at my disposal that might mitigate this effect?
Has anyone else used TOL's downstream of a powerflex 525 (or any other drive), and did you see the same results? How did you ultimately solve it? Are there some thermal overloads on the market that work better on the load side of a VSD than others?
These overloads are all constantly tripping, even when set 10-20% above the motor nameplate current. The motors are not drawing anywhere near nameplate current.
I figure there must be something about the drive that generates additional heat in the simple bimetallic strip in the TOL's, over and above what the actual current draw would normally cause. Do I have any parameters at my disposal that might mitigate this effect?
Has anyone else used TOL's downstream of a powerflex 525 (or any other drive), and did you see the same results? How did you ultimately solve it? Are there some thermal overloads on the market that work better on the load side of a VSD than others?