Automatic rail system vfd type vs torque

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Discussion Overview

The discussion revolves around the challenges faced by an automatic rail system used for transporting cows, particularly focusing on issues related to starting torque and the effects of environmental conditions on performance. Participants explore different types of variable frequency drives (VFDs) and their impact on torque control, as well as potential solutions to improve system reliability and efficiency.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Experimental/applied

Main Points Raised

  • Some participants note that the current VFD is a standard volts vs. hertz drive, which may have poor torque control below 50% load compared to other drive types like flux control or sensorless vector drives.
  • One participant suggests that the system may be improperly sized, leading to nuisance over amps during startup torque, and proposes that larger motors or drives could be a quick solution, while cautioning about potential mechanical damage from increased low-range torque.
  • Another participant mentions that a drives company is conducting trial runs with different motor types and VFDs to address the torque issue.
  • There is a mention of operational constraints due to the food industry, which prevents the use of automatic oilers, necessitating manual lubrication of the rail chain.
  • Participants discuss the possibility of slowing down the system to reduce peak torque demands as an alternative solution.

Areas of Agreement / Disagreement

Participants express differing views on the best approach to resolve the torque issues, with some advocating for larger motors and others suggesting adjustments to operational speed. The discussion remains unresolved regarding the most effective solution.

Contextual Notes

Participants acknowledge environmental factors affecting torque, but there is uncertainty about the specific impact of these factors on system performance. The discussion does not clarify the assumptions behind the sizing of the current system or the implications of switching drive types.

Who May Find This Useful

Engineers and technicians working with automated transport systems, particularly in the food industry, may find this discussion relevant for addressing torque control challenges and exploring VFD options.

Mordred
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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 definitely help

edit: slower ramp up was already considered and the ramp speed is as slow as production speed allows
 
Last edited:
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We founds a drives company that is going to try different motor types and VFD's on trial runs to deal with this issue.
 
However has nuisance over amps on startup torque.

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.
 
Yeah that's 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
 

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