automatic rail system vfd type vs torque

Mordred

Working on a problem with an automatic rail system used to transport cows. This rail system carries a substantail amount of weight so starting torque is the issue coupled with washdown ( rust) issues. The system runs well normally even fully loaded. However has nuisance over amps
on startup torque.

The vfd is a standard volts vs hertz drive with line reactors.
I'm wondering which drive type would have better torque control
Voltz vs hertz drives have poor torque below 50% compated to a flux control drive or senserless vector drive.
Can't recall offhand the fourth drive type.
This drive system has numerous start stop cycles so smoother torque control would definetely help

edit: slower ramp up was already considered and the ramp speed is as slow as production speed allows

Mordred

We founds a drives company that is going to try different motor types and VFD's on trial runs to deal with this issue.

tygerdawg

I could be wrong. This seems like the key to your problem. The system was improperly sized because it did not account for the environmentally-induced torque penalty. Quickest solution: get bigger motors / drives. But verify the extra low-range torque does not do any mechanical damage to the driving elements.

Or...slow it all down to reduce peak torque demands.

Mordred

Yeah thats why we have AB coming down with their specialists to trial run drives and motors. The trial run will be a 1 week duration. If that doesn't work they will look into stepping up the motor.
One of the hassles is due to food industry we cannot use automatic oilers so the rail chain has to be manually lubricated on the weekend then wiped off