Posted 13 July 2007 - 11:48 AM
We have on site one chain conveyor which is driven by a 30 kW 6 Pole motor which is itself coupled to a 150/1 gearbox. The maximum speed setting on the VSD is 35 Hz. We are facing a gear problem on the gearbox and we have only one rated 360/1 gearbox available. I have suggested a 2 Pole 30 kW motor in lieu of the 6 Pole motor. This means that the max. setting of frequency on the VSD will have to be adjusted to around 28 Hz to match the application. The VSD is a sensorless flux vector type but I am afraid the torque available below 5 Hz on the 2 Pole motor will not be sufficient to start the conveyor.
Any comment !
Posted 13 July 2007 - 07:58 PM
Yes, I agree. You could be in a lot of bother getting a loaded conveyor to run.
It does depend on the VSD though. I replaced a well known brand of VSD on a drum drier application because the VSD failed, with a different brand of the same size and what a difference. With the original, it was always a fight to get things going. With the replacement, there is no problem at all. - just a lot more torque at zero shaft speed.
Your torque at low speed is going to be less than you currently have. If the system stqarts very easily, you may get away with it. If the system is currently only just making it, then you are in trouble. Unfortunately, there is no easy way to find out.
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